Roger Tanner

McKinley:

All right, so well, so today is May the 8th, 2019. I'm sitting here with Roger Tanner in Roseville, which is a suburb of Sydney, and I'm here to interview Roger as part of the Society of Rheology history project. So thank you for the hospitality, Roger.

Tanner:

Pleasure.

McKinley:

So why don't we start straight away by thinking a little bit about your youth and growing up and you were telling me about your early childhood.

Tanner:

Yeah, so I grew up in country England, in Somerset, in a community of about 300 people. And one had to learn to entertain oneself in such an environment. My father was a fitter and turner, and he died as the result of a stray German bomb in 1942. And so after that, we lived with my maternal grandparents in Henton, a small village in Somerset. And Grandpa, who was a former miller, was an avid reader and there were many books and so forth, but Grandma didn't like to see me reading. She thought that was a total waste of time, and I should do something useful. So, you know, that was the background of my school days. But Grandpa had a bench and some tools, and I spent a lot of time making models. Tractors, aircraft, boats, steam engines, boilers. And that was fun. I went to the local grammar school in Wells, the Blue School, founded in 1642.

McKinley:

And you go there roughly when you were 11? Right? (crosstalk 01:43)

Tanner:

This is to 11, yeah. It's after school days, I didn't really want to go to university at that stage, though I could have. I went to the Bristol Aeroplane Company as an apprentice in the engine division. It's part of Rolls Royce now. It's not autonomous.

McKinley:

Were you working on propeller engines or jet engines?

Tanner:

That was what was so good about it. I went there and it was in the transition period. Going from big piston engines to the jets. And the piston engines were wonderful devices with 18 cylinders air-cooled and wonderful machining. Just beautiful construction. But the coming thing was the gas turbines and they demanded all sorts of different skills. And what the company did was they took the chief engineer, moved him sideways to continue to look after the reciprocating engines, and then they hired a new person who was an Oxford PhD actually. A mathematician called Stanley Hooker, to guide the development of the turbine. So it was a very interesting period to see the new technology being developed.

McKinley:

Yeah. But that only lasted a year or two?

Tanner:

I was there three years, and I won all sorts of prizes as an apprentice, and then the company gave me a scholarship to go to study mech eng [common English abbreviation for mechanical engineering] at Bristol University. And that worked out very well. I got the Albert Fry prize at the end of it, which was for the best undergraduate performance in engineering over three years. So that worked. And then I got interested in metal plasticity for my graduation thesis, and--

McKinley:

Were you doing experiments, or?

Tanner:

Yes, I was doing experiments which involved stretching a piece of metal with a groove in it and the groove would cause plastic flow in that area. And the idea was to correlate it with some theories that were in the literature, and I had to read Rodney Hill's book on plasticity, which is absolutely a fantastic book. And it still is. So I still have a copy of it.

McKinley:

You've probably seen there's a Hill prize now in solid mechanics.

Tanner:

Yeah, probably. Well he was the editor of the Journal of Mechanics of Physics of Solids for many years. And of course he was a fellow of the Royal Society and all of that. And yeah, it was... So I was lucky because I got Bernard Crossland as supervisor. And Bernard became Sir Bernard Crossland FRS after a long time. And I kept in touch with him. And he was a great supervisor, because he left me completely alone to do what I wanted (laughs) except when things really went wrong.

McKinley:

So you were making your own samples and machining your own samples and things like that?

Tanner:

Yeah, yeah.

McKinley:

Yes, yeah, mmhmm.

Tanner:

He would step in when special things went wrong, if the workshop was very slow or something. But it's probably [how] I inherited this light style of supervision (laughs) for my own students, you see.

McKinley:

So hands-off. A kind of a laissez-faire--

Tanner:

Hands-off.

McKinley:

Yes.

Tanner:

Let them go and do what they want and develop themselves, but rescue them if you have to. And I have a whole series of PhD students going from people like (Nhan Phan-Thien) all the way down to some others which I won't mention where you have to have hands-on with them. I mean I've got one now that, my last PhD student, I have to see him every week.

McKinley:

Mmhmm. Just to keep him on the rails, right?

Tanner:

To keep him going. You may have experienced this as well.

McKinley:

Yes, it covers a spectrum, yes. Yes. So but anyway, this got you interested in research, I guess.

Tanner:

Oh yes.

McKinley:

Because this was your last year of undergraduate days.

Tanner:

Yeah. But then I got this opportunity to go to California with this King George VI Memorial Fellowship, and I wanted to do something different from plasticity, so I wanted to do control engineering, and that couldn't be done in Mech Eng at Berkeley. It was done in Electrical. So I went into electrical. But as I mentioned, I sneaked in an advanced course on elasticity and a course on hydrodynamics, which (laughs) were just terrific.

McKinley:

And the hydrodynamics class was by Paul Chambré?

Tanner:

Yeah, and he was a very good teacher. He was the best.

McKinley:

Was he French originally, with a name like that?

Tanner:

No, he was just pure American, but he was French origin, I guess. His parents had been French. Yeah.

McKinley:

And who taught the elasticity class?

Tanner:

Karl Pister, who was a young assis-- I think he was an assistant professor at the time, but we had all these general tensors in this elasticity course. Anyway, he did well. He eventually became the chancellor at the University of California in Santa Cruz, so he was-- I kept in touch with him as well. That was all very good meetings.

[GM. Pister in fact just passed away in 2022 at age 96. https://news.ucsc.edu/2022/05/karl-pister-in-memoriam.html]

McKinley:

Interesting. And those were-- those classes I guess were in mechanical engineering?

Tanner:

Well, Chambré was a mathematician.

McKinley:

Okay, mmhmm.

Tanner:

And Pister was in civil engineering.

McKinley:

Okay.

Tanner:

But you know, the way with graduate courses, you've just got to get the number of units.

McKinley:

Yes. And you had to do a thesis as part of that masters degree?

Tanner:

Yes, and that's the next part I was just coming to. Because I'd run out of money, I had to take a job, so the only job that was really suitable was with a guy called Bill Rouveral, who was an inventor. He really wasn't a great academic. And he wanted some work done on friction and lubrication, so I signed up to do this, and it really involved-- He'd invented a variable speed transmission for automobiles, and it involved spheres rolling over plates. And you needed to know how much drive you could get, how much friction you could get. So I took this over and fixed the rig, which he didn't do a very good job on designing the rig. And did this work, and again, that was a good thing that he didn't bother me, because he was building a house up at Inverness in California, and he left me alone. (laughs)

McKinley:

Okay. So again, again, hands-off.

Tanner:

Hands-off. So this, we wrote a paper on this, and it was in the ASLE transactions, I think. About my third or fourth paper with Rouverol. It's still not a bad paper, considering. And when I looked at this website in 2015, this Rouverol was still alive. He was 96.

[GM. The paper is “Brief Examination of Factors Affecting Tractive Friction Coefficients of Spheres Rolling on Flat Plates”, A.S.L.E. Transactions, 3, 1960, pp.11-17 (with W.S. Rouverol).]

McKinley:

Gosh.

Tanner:

So he might have popped off by now, who knows. Anyway, so then I met Elizabeth and we were married, and then I--

McKinley:

Where did you meet her?

Tanner:

On the campus at Berkeley.

McKinley:

Berkeley, okay.

Tanner:

She was a student in law, and I was doing my masters degree. And then-- we met at International House, actually. Because that's where we were living at the time.

McKinley:

And Elizabeth's background, or nationality?

Tanner:

Yeah, she's pure Californian. Born--

McKinley:

Born a California girl.

Tanner:

A very rare breed in those days. As you know so many immigrants and so... Anyway, during this period, I read Houwink's rheology book. You know it.

[GM. Elasticity, plasticity, and structure of matter, Houwink, R. (Roelof), 1897-1988. (Cambridge Eng. University Press), 1954, 2nd ed.]

McKinley:

I know it, yes.

Tanner:

It's such a good book. And it covers all these incredible materials, including bread dough, so that was quite inspirational. It was due to the-- you know the Dover company used to put out these reprints of these, and they were only a couple of dollars each.

McKinley:

Yes, they still do it.

Tanner:

That's wonderful. So anyway, that was my first rheological encounter. And then we went back to the UK, because I thought that we were going to have to do military service, but it turned out it wasn't the case. If you had a first class honors degree, they said you were better off in industry, so I went back to Bristol...

McKinley:

And Elizabeth came with you at this point?

Tanner:

Yes.

McKinley:

You were married by now?

Tanner:

We were married. She came back. And this, the Bristol Aircraft Company at that point, it was so boring because they weren't going to develop any new engines. It was one of those things where the Ministry of Defense had turned off the tap and there was nothing new going on. And so after about three months, I applied for several jobs, and I could have gone to ICI up in the north or I could have gone to Farnborough, in the Royal Aircraft Establishment, but I got a job as an assistant lecturer at Manchester University. And I enrolled simultaneously as a PhD student, which you could do in those days. It was quite normal to be a junior academic and—

McKinley:

I was wondering about that, because you list yourself as a lecturer at the same time as a student.

Tanner:

Yeah, yeah, I was. So once again, my supervisor was Jack Diamond, who was the head of the school. But he was purely nominal. He hadn’t got a clue what was going on, and he had no idea of doing research. He was an administrator, so once again, it was a hands-off (laughs) thing.

McKinley:

I see a pattern here, yes.

Tanner:

Yeah well that is my independence, I suppose. But the good thing was a man called Bill Johnson. I don’t know if you ever knew Bill Johnson.

McKinley:

No.

Tanner:

He became a professor of mechanics at Cambridge.

McKinley:

At Cambridge, this is as in Johnson from J.K.R. theory? Johnson–Kendall–Roberts?

Tanner:

No, that’s another Johnson. That’s Ken Johnson, this is Bill Johnson.

McKinley:

Okay, I don’t know Bill Johnson, then.

Tanner:

Well anyway, he died, but he was basically at Manchester, the shining… He knew how to do research and so he was a good mentor. So anyway, one day Bill, oh he became a fellow of the Royal Society as well. And anyway, Bill one day-- I was doing some work on lubrication, and he said why didn't I go to Sheffield to see his friend Phil? And I'm sorry, I've forgotten Phil's name. But I went to Sheffield University, I remember I went on the bus. You could go by bus in those days easily. And I went to Sheffield, and we chatted about lubrication for an hour or two, and then right at the end, he said had I ever considered the effect of viscoelasticity on lubrication? (laughs)

McKinley:

Uh-huh. And people still struggle with this.

Tanner:

(laughs) I said no, but I would look into it. And so that's how I began to be submerged in rheology quite by accident, really.

McKinley:

So I see that several of your first papers are indeed on lubrication theory with Maxwell fluids.

Tanner:

Yeah I know, it's really amazing what we were trying to understand in those days. The other lucky thing was that Geoffrey Allen, who was eventually Sir Geoffrey Allen FRS, lived in the flat underneath us in Manchester, and he suggested I go and visit Arthur Lodge. Lodge was--

McKinley:

Where was he at the time?

Tanner:

He was working at the Rayon Research Institute in Manchester at that time. And so Lodge introduced me to the literature generated by Clifford Truesdell and his satellites. And very sporting of him, he suggested I read it! So I did. And I also met Jim Oldroyd in Swansea and Ken Walters as well.

McKinley:

So this must have been about 1960? Two years into a PhD?

Tanner:

Yes, '58, '59, '60 is, yes.

McKinley:

Tell me about Jim Oldroyd, since you mentioned him.

Tanner:

Oh yeah, he was interesting. A bit off the planet, I thought he was. He wasn't really a very dynamic man in many ways. I don't know if you ever met--

McKinley:

I never met him, never got to meet him, no.

Tanner:

Of course Ken knows him better than me.

McKinley:

Yes, very well.

Tanner:

But anyway, we--

McKinley:

Was Ken doing his PhD with him at about that time?

Tanner:

Yes, I think so. Yeah. Yeah. So I was able to, through Lodge and through Geoffrey Allen and Johnson, to go and visit some very useful and important people. And I collaborated with Frank Leslie, as you asked a question about that. Now he became an FRS of course. On some flows around spheres. Now, I'd started on a perturbation of the flow around a sphere, but Frank was in Applied Maths, and was a much better mathematician than I'll ever be, so he... In the end, I did some experiments and that's how I came to be in an appendix to his paper.

McKinley:

…Paper, right. I always find this very interesting because it's a paper, everybody refers to it as Leslie and Tanner, but in reality, there's a paper--

Tanner:

It's really Leslie.

McKinley:

And then there's a Tanner appendix, right, which is the experiments.

Tanner:

So anyway, Frank was a good person to collaborate with, and I used to go to all the applied maths seminars, because they were very powerful in those days, you know, Jim Lighthill was there. And David Bland, who wrote a nice book on viscoelasticity. And Frank Leslie was there as a lecturer. And a man called Eric Watson, who was really a very clever guy too.

McKinley:

And Arthur was on the maths faculty, or he was--?

Tanner:

No, Arthur, Arthur--

McKinley:

He was at the Rayon Institute.

Tanner:

He left the Rayon Institute and went to the other campus, the one-- the technical campus downtown. The Faculty of Technology.

McKinley:

I think it was called-- Was it called UMIST later?

Tanner:

UMIST later. It was separately, yeah. And now it's been re-amalgamated.

McKinley:

And then been re-amalgamated now, yes. Yeah.

Tanner:

Yeah, interesting. Anyway, so I finished up my PhD and went to Sydney. Why did I go to Sydney? Well, I didn't really like the Manchester climate. It was very cold and wet and so we came down here-- and it was the wanderlust again, you know, you get wanderlust. So we came here in November 1961. Oh the other real reason for-- the real reason I was looking for another job was because at that time, the British universities had a rule that you could not have more than two people out of nine higher than a lecturer in a department. So here I am, a lecturer.

McKinley:

And nowhere to go.

Tanner:

No! There are two or three people ahead of me already. I'm never going to get promoted. (laughs) So I quit.

McKinley:

Right, and it stayed that way for a long while. You could only have one professor in a department or something for a long time. So yeah, so that's a big trip in those days. Sixty one how did you get from Manchester to Sydney?

Tanner:

Oh in great luxury. We were given a first class passage on a boat.

McKinley:

Wow. How long did that take?

Tanner:

28 days.

McKinley:

That's quite the adventure then, yes.

Tanner:

It was lovely, and the other good thing was of course that cooks were, a lot of the cooks were from India, and we had 21 different curries for lunch. (both laugh)

McKinley:

And the university provided the ticket? As part of the package?

Tanner:

Actually it was the New South Wales government, and they paid all our expenses, and there was a moving expense and everything, and when we got here, the university had a house for new faculty, and we moved into that flat for nine months while we had a house built. So that was-- it all worked out very well, and as you say, I became a Reader after a few--

McKinley:

Three years.

Tanner:

Three years, and that worked out. What else?

McKinley:

Well so during that time, did you-- you must have started to go to rheology meetings. There was a big International Congress in 1963 in--

Tanner:

That's the one I met Ken at and we heard Giesekus. You saw my Obituary

McKinley:

We did just see that, that was just published in Rheologica Acta, yes.

[GM. R.I.Tanner, K. Walters; Hanswalter Giesekus 1922-2017; Rheologica Acta (2018) 57 pp. 691-692]

Tanner:

Well the same-- a variation of that is in the Rheology Bulletin too.

McKinley:

Oh maybe that's where I read it, yes. Yes.

Tanner:

Anyway--

McKinley:

So you met him there? He was at that meeting as well?

Tanner:

Yes, he gave a brilliant talk about a rotating sphere in a viscoelastic fluid and he had these experimental evidence and he had the calculations to go with it. It was really a most striking performance. So that was very satisfying, and then the following year, in 1964, I went to an SOR meeting. My first one. And--

McKinley:

Where was that?

Tanner:

That was at Pittsburgh. And I remember Krieger was in charge of the program, and afterward, I went and gave a talk and it was a talk on oscillation and simple shear this was, simple shear this way, and oscillation this way, [GM. Roger was indicating with his hands in orthogonal directions here; this is what is now known as OSP or Orthogonal Superposition rheometry] that John Simmons, who was a very good student, was doing. But we were having trouble with the phase angle measurements at the time, and when I got to Pittsburgh, I could-- all I could do was give a progress report. And Irwin took mortally offended about this. (both laugh) And he's never really liked me since. (laughs)

McKinley:

Really? Because it wasn't a complete piece of work?

Tanner:

It wasn't a complete piece of work, and he'd made room for it and I guess he... Anyway, that was my first SOR meeting.

McKinley:

Do you remember who won the Bingham medal that year?

Tanner:

No.

McKinley:

No?

Tanner:

No, I'll have to look it up. It was 1964.

[GM. It was actually J.M. Burgers (then at the University of Maryland) for his work at Delft leading to the Burgers Model.]

McKinley:

--4, right.

Tanner:

Then soon after that, I got a letter from Brown University asking me if I wanted to be an associate professor there. So I said yes. Because at that time Brown was really the mecca for mechanics.

McKinley:

Rivlin was very active.

Tanner:

And everybody and so we took it up, and we went in September '66 to Providence. As we arrived, Ronald Rivlin left. (laughs) He went to Lehigh.

McKinley:

Right, okay.

Tanner:

I saw him once in the bank, when he was closing his account. (both laugh)

McKinley:

I see, okay, yeah. He'd had a very tough time, I think, trying to run that group or keep that group together.

Tanner:

Well... the problem was that Rivlin and Prager, who was the other prima donna, didn't get on at all. They were totally different personalities. And I think... Anyway, he went to Lehigh and I think he had a very comfortable time down there, because they set up an Institute for him.

McKinley:

--institute for him, yes, yeah.

Tanner:

Anyway, it didn't matter so much because the person I really collaborated with was Pipkin, who was absolutely fantastic, and I have a few notes here about Pipkin, because I really rarely met people like him. And he died when he was 63, you know?

McKinley:

I didn't know that. I don't know very much about actually. So, apart from his book in linear viscoelasticity.

Tanner:

A very good book. He was very exceptional. He could see very clearly what was needed to solve a problem, and he did it. And in that way he was like Rivlin. He learned that off Rivlin. Rivlin used to say, "Look, what you do is you just hammer away at something until it comes out." That's-- (both laugh)

McKinley:

It's not always that easy, but it's certainly worth trying, yes.

Tanner:

So anyway, we did a lot of good things, and--

McKinley:

So the Pipkin-Tanner theorem comes from those days?

Tanner:

Yeah. That's right, and we did the pressure hole over a ditch thing.

[GM. For more on the “hole pressure effect” and the Pipkin-Tanner Theorem see Bird et al., Dynamics of Polymeric Liquids, Vol 1 (2^nd edition) 1987.)

Tanner:

That worked out well, and in fact--

McKinley:

Can you tell us anything about-- he was working a lot, thinking about linear and non-linear elasticity. What many of us now call the Pipkin diagram, I know.

Tanner:

Yes, yes.

McKinley:

Because I think that's the first place where many of us saw that, but maybe it came from something else or earlier discussions, or?

Tanner:

No, I think he sort of came to it when I was there in the 60s. He realized that there was a magnitude of-- there was a frequency thing and there was a magnitude thing, and we knew a little bit about the edges, but in the middle there was a big question mark. So I've always found that a very useful summary of what went on. So anyway, one day at two o'clock-- Jack used to work, he used to go to his office about four o'clock and then leave at about two or three a.m., you see. (laughs)

McKinley:

Wow, okay, uh-huh.

Tanner:

So one night he phoned me at two o'clock to say, "Successfully calculated the pressure error." (laughs) Oh gosh.

[GM. “Intrinsic Errors in Pressure-Hole Measurements”, Trans. Soc. Rheol., 13, 1969, pp. 471-484 (with A.C. Pipkin).]

McKinley:

And you weren't at work at the time, I imagine. You were in--

Tanner:

I was half asleep.

McKinley:

(laughs) Uh-huh.

Tanner:

Anyway, at parties, he used to, well, he was a really good lecturer, and I sat in on his lectures on continuum mechanics, but he didn't use any notes. Had no notes whatsoever and he smoked continuously throughout the lecture. You can't do that anymore.

McKinley:

Not anymore, no. No.

Tanner:

But he used to light one cigarette from the other as he went--

McKinley:

Yeah, as he ended one? Gosh. And lecturing was on the blackboard, I presume?

Tanner:

At the blackboard. But he was very good. And at parties, he used to throw himself down a flight of stairs, and one day he broke his wrist doing this, and he explained that this happened because he wasn't drunk enough, and he wasn't relaxed. (both laugh)

McKinley:

So he would do this as entertainment?

Tanner:

Yes, yes.

McKinley:

This was an entertainment--

Tanner:

He would just throw himself down a flight of stairs, roll down. (laughs)

McKinley:

Fantastic, wow.

Tanner:

A fantastic fellow. The other person that I really enjoyed at Brown was Bob Nickell. I don't know if you've ever met him.

McKinley:

I don't know that name, no.

Tanner:

Well he was a finite element man, and he and I were sitting in the airport at Washington, as so often happened trying to get a flight to Providence, because there aren't that many. And one day we decided we would do some fluid mechanics. So that was very fruitful, because--

McKinley:

And Jack Nichol, that's N-I-C-H-O-L? Or?

Tanner:

No, it was N-I-C-K-E-L-L. Bob Nickell. He, anyway, we wrote this 1974 JFM paper on Die-Swell, which is one of my first best things. Anyway. Bruce Caswell was a co-author on the paper, but I don't know whether I should tell you, Bruce didn't do anything, it's just that he had some computer time that we used up. (laughs) You remember the days?

McKinley:

Yeah the days when you had to have an account--

Tanner:

You had to have money or an account or something. Yeah. Anyway, so Bruce--

McKinley:

So where was the computer at the time? Was it on-campus, or was it a remote, or?

Tanner:

Yeah because Watson was chairman of IBM, and he was a Brown undergraduate. So we used to get pretty good deal with IBM and we had an IBM, I think it was a 360, I think it was at the time. But do you know, the difference between that and this [pointing at his laptop] is really the memory that could be stored because these things now have practically infinite memory, whereas you couldn't even leave your program on the machine overnight in the days when we started this computing.

McKinley:

You had to erase everything, right? Get the data off, erase the program...

Tanner:

Well you had a deck of cards. They had to be read in, every time we used the program. And if it didn't run, then that was the waste of a day, really, because it would only run it at night, because it was the biggest job. And the other trouble was they had temporary staff on at night, undergraduates earning a bit of money, but the trouble is, they were potheads a lot of them, and sometimes they'd drop your deck of cards on the floor. (both laugh)

McKinley:

And then it's all random order, right?

Tanner:

Into random order, and then they say, "Well it didn't run." (laughs)

McKinley:

There would be a reason for that, yes. Yeah. So this was Finite Element?

Tanner:

Finite Elements. And it's published in JFM in...

McKinley:

'74?

Tanner:

'74. That was one of the best... Anyway, Bob Nickell became president of the American Society of Mechanical Engineers. And then he died early in 2015.

[GM. He was the 118th President; https://www.asme.org/topics-resources/society-news/asme-news/robert-nic…]

Tanner:

It was sad. I had four PhD students at Brown and three of them went into industry. The fourth one went to Tel Aviv University in Israel.

McKinley:

And who was that?

Tanner:

Moti Sokolov? I don't think you've ever--

McKinley:

No, I don't know him.

Tanner:

But he got out of rheology and went back into boundary layer theory. I think as soon as he could. They all required much better supervision than my first students at Sydney, who were Simmons and Huilgol, you've met Raj….

McKinley:

I know Raj, yes. Yes.

Tanner:

So they were pretty much self-starters.

McKinley:

I didn’t know know Simmons, but I know that there’s Simmons-Tanner damping function, which you developed with him. But you told me that, I think he went on to become dean?

Tanner:

Yeah, he became dean up in Queensland and he really... His interest was really in instrumentation. He really wasn't very interested in rheology as such. But he was good at administration... at instrumentation.

McKinley:

And he built one of the first, these orthogonal rheometers right, where you could oscillate it vertically as you sheared it.

Tanner:

That was a wonderful piece of engineering, and he designed it and with the help of a company, he got it built. It was really... Anyway, you asked about sabbatical leave.

McKinley:

Yes, yeah, so did you... You had a chance to go on sabbatical, or maybe you had people come visit you on sabbaticals?

Tanner:

Well we had a chance to go once at Brown, and we went to Grenoble. And somehow or another, I got some money from the French government there. I've still got the appointment signed by Georges Pompidou, who was the president at the time. I never had so much money in my life, because I was getting a half salary from Brown, plus this salary from France which was even bigger than the Brown salary. And the income tax in France was 5%.

McKinley:

Oh gosh, okay. Uh-huh.

Tanner:

So it was an amazingly good deal.

McKinley:

And how long were you there? Was it six months or a year?

Tanner:

A year.

McKinley:

A year. And were they doing scattering experiments then? Was this before?

Tanner:

This was in the soil mechanics, I think the unit was called. And there was a couple of guys there who were trying to develop a co-rotational model.

McKinley:

For soil.

Tanner:

A rheological model for... But I never could see eye-to-eye with them and so we never really wrote anything together, but it was a really, really lovely place, too. We sent all our five children to local French schools, and that was... So some of them are still very good French speakers.

McKinley:

Oh that's fantastic. So you had all five with you at that point?

Tanner:

Yes.

McKinley:

Yes.

Tanner:

Yeah, we had all five there. And Rebecca, who was then five, she'd never been to school before, so you can imagine the shock of going to a foreign language school when you're five.

McKinley:

Yeah, amazing, but they're very adaptable, right?

Tanner:

She seemed to have been.

McKinley:

Yeah. So that was '72, I think, you were there.

Tanner:

Yeah that was '72.

McKinley:

Yeah so after a couple of years back, you then went back to Sydney.

Tanner:

Yeah I had once before turned down the job as the P.N. Russell Professor and, because I hadn't been at Brown more than three or four years and I thought I would stay a bit longer. But the second time it came around, I said I'd apply. And I got the job. So that was, came back here in '75.

McKinley:

And so who was P.N. Russell? Just as an endowed chair, or…?

Tanner:

Yeah, he endowed the chair. I have a whole lot of stuff about P.N. Russell, which I don't think you want to know. about, but his family had a tremendous ironworks in Sydney in the 1890s, the 1900s, and if you look around the older suburbs of Sydney, you sometimes see a lot of houses with railings, fancy iron railings. And he made his money because there was a huge housing boom, and he supplied all the iron railings for the new developments. And then there was a big strike, and so they closed the whole thing down. They just said we'll lock you out. We'll be on strike, but we're not going to do anymore. So anyway, Russell went to London, and one of the Sydney University chemistry professors actually went there and found him more or less on his deathbed and got him to sign up two professorships. (laughs) One in electrical and one in mechanical.

McKinley:

Well done to that development person. Yes.

Tanner:

(laughs) I said, well, that was wonderful. So that's where the P.N. Russell comes from. He was an iron-founder and he left money.

McKinley:

And you've held that chair ever since 1975.

Tanner:

Yes I have. I had four full years in the administration, as pro-vice chancellor, that was in those days the second or third? No, there was the vice chancellor, the deputy vice chancellor, and then there was me. Looking after research. And four years of that was enough, to be honest.

McKinley:

I can believe that. But before that, you'd been department head multiple times.

Tanner:

Oh yeah, oh yeah.

McKinley:

That's a rotating chair in Sydney? That's kind of, it's two years on and then off?

Tanner:

I used to share it with my colleague Bilger, who liked the job much better than I did I think. So two years on, two years off.

[GM. Robert William Bilger 1935-2015, Tanner, RI and Masri, AR Dec. 2016, HISTORICAL RECORDS OF AUSTRALIAN SCIENCE 27 (2) , pp.133-143]

McKinley:

Right.

Tanner:

Right. And then when I'd finished with being pro-vice chancellor, I was almost 65 and I decided that a part time appointment would be appropriate from then on. So that's what I've done since 1965, it's 20 years almost.

McKinley:

No, so it's since 1995.

Tanner:

Sorry, from 1995. Sorry. 20 years of--

McKinley:

Part time.

Tanner:

Part time work, which has been really very nice.

McKinley:

So one of your first students when you got back in 1975 must have been Nhan Phan-Thien.

Tanner:

Yes, he graduated-- I got back in July, and he was looking for something to do by December for when he graduated. He was an undergraduate.

McKinley:

As an undergraduate, okay.

Tanner:

And at the time, he couldn't really go back to Vietnam because his father had been on the losing side in the war, and it (laughs) wouldn't have been a very good idea.

McKinley:

And the war was only just over by then, right? It was only-- yes, yes.

Tanner:

So he signed up with me, luckily, and of course he was just a great PhD student that you didn't need to do anything really. I had others who were very good. A guy called Mark Bush who came from Queensland and he went to Western Australia and became dean. Xiao-Ling Luo, who was really a very clever numerical person, but he works at CSIRO now. Craig Beverley, who runs his own consulting thing down in Victoria. Shicheng Xue, you may have--

McKinley:

I've met him, yes.

Tanner:

Shicheng is very clever. He just likes to do research. He doesn't want to do anything else.

McKinley:

And where is he now?

Tanner:

He's still in Sydney.

McKinley:

Still in Sydney, okay. Mmhmm.

Tanner:

And Ahmed Jabbarzadeh, who you'll meet at lunch. He was one of my students, and he's started this molecular dynamics stuff. And that was fine. And then another one called Rong Zheng, who was interesting. He came from Guangzhou, when it was the Polymer Institute there, and we'd never heard of it at all. Never heard of this place. So, when he arrived, I sent him a little problem to do as a, you know, "Do the analysis of the calendaring of a viscoelastic sheet." Well this chap disappeared for about three months and then (laughs) I was a bit worried about it. And then he came back one day and he said, well, here is the answer.

McKinley:

And he'd done the whole thing?

Tanner:

(laughs) He'd done the whole thing. We just published it in JNNFM (laughs) and he’s the sort of guy you want.

McKinley:

Right, yeah, indeed. Indeed. And he was doing something with—this was viscoelastic, or?

Tanner:

Yes, it was a Maxwell [fluid].

McKinley:

So you had told me once about Nhan Phan-Thien, I think, and his name, or...?

Tanner:

Yes, well when he was an undergraduate, he had inadvertently written his name down the wrong way round, so all through his undergraduate career, he was called P.T. Nhan. (laughs) And then he graduated as P.T. Nhan with the university medal and all this, you see. And then ultimately, he said, "You know, really my name's not Nhan, is not my family name." (both laugh)

McKinley:

So the family name is Phan-Thien.

Tanner:

Right, yes. And apparently it just means Mr. Rice.

McKinley:

What does?

Tanner:

Phan-Thien.

McKinley:

Does it really? Okay, Mr. Rice.

Tanner:

I think so. That's what Bob Bird said one day when I was talking to Bob. Bob was a great student of--

McKinley:

Of languages, yes.

Tanner:

Of those languages. And so anyway, we've had some good students here, and as I said, Rong Zheng was excellent. But his command of English was never good enough to be an academic. So he went to work for Moldflow which was really good because we had this eleven year association with Moldflow doing work on injection mulling. That was really good. Well that's background. Now where are we up to?

McKinley:

So would you like to take a break, or?

Tanner:

No, I'm all right.

McKinley:

No, you're great?

Tanner:

Do you need a break?

McKinley:

No, I'm fine, I'm great. So I think we're into-- we're stuck into the middle of thinking about research and students, things like that. So, tell us a little bit about the Phan-Thien-Tanner model, mainly because I think if you look at the most-cited works, that's the work that's probably been the most heavily-cited over the years. How did that come about?

Tanner:

I think it's about over 1000 citations on Google Scholar, but you know, Google Scholar is always--

McKinley:

Always optimistic, yes, yes.

Tanner:

It's around 500 or 600 on the--

McKinley:

Web of Sciences?

Tanner:

No, on the Web of Sciences, probably about 300, but there's a Scopus, a Scopus that’s other one, yeah. Well anyway, what happened was that Nhan wanted to do something on fairly mathematical-- you could see, because he had real talent with mathematics. Still does, I guess. And so I said, why doesn't he look at Arthur Lodge's book on network theory and do something about it. So I don't know, he went away and worked at it, and then of course you come up against a closure.

McKinley:

Yes, mmhmm.

Tanner:

Because you've got an integral over a probability, which you've got to deal with. It just so happened that I worked out a closure scheme for dilute solutions before that. When I was at Brown.

McKinley:

Yes, using a very simple form of, essentially a delta function.

Tanner:

Delta function, yes. Using a delta function. So we used the same trick, and out came the PTT model basically. So there was a contribution there from both of us.

McKinley:

Yes, and there are several papers on different…then…forms of a stretching law.

Tanner:

Yeah, well Nhan worked out various steps in it afterwards. So it was really good to have that collaboration with him, and the fact that he stuck to it. The only thing it never did, it never generated a second normal stress difference. I still can't figure out how to do that. (laughs) I haven't worked that one out.

McKinley:

Without putting it in through a slip coefficient or through a Gordon Schowalter

Tanner:

Oh yeah, yeah, well that's right. Oh yes, you can have that. You can have an N2 and a slip coefficient. But I'm a bit leery of slip coefficients to be honest. I don't know about you, but they cause all sorts of--

McKinley:

They cause all sorts of other troubles, yes, yes.

Tanner:

They do, yes.

McKinley:

But I was going to bring that up, because another person I've chatted with has been Bill Schowalter, and so in his book, he acknowledges you explicitly as having read the proofs of his book, which was in the late 70s, one of the first books on this.

Tanner:

Yes.

McKinley:

So do you remember, you knew each other well? Or?

Tanner:

Well we got to know one another quite well, because as I said, I went to Princeton a few times and gave talks and he came out to Brown and gave some good talks, and we used to meet at conferences. And we had a lot of other interests together. We were rabid tennis players and so forth. So that's one of the reasons he's got to still be so fit, because he's always a skinny guy.

McKinley:

He still is, yes, yeah. I don't know if he's still playing tennis, but you're telling me you don't play tennis, you play golf now.

Tanner:

I play one set of tennis every Sunday morning with this family.

McKinley:

Do you now? Fantastic.

Tanner:

Yeah, but I can only do one set.

McKinley:

Yeah. So since we're talking about research and Arthur Lodge and Bill Schowalter and people like that, I know you spent some time at the Rheology Research Center in 1984. That was another sabbatical.

Tanner:

That was great. That was a great visit. They had money in those days. I think from the army or something like that. And they invited me to come, and so we went there for six months, and it was--

McKinley:

So who was your host then?

Tanner:

Well it was Arthur [Lodge] and Bob Bird.

McKinley:

Ah both of them, mmhmm.

Tanner:

Yeah, together. The Rheology Research Center actually is, that's what it was. And the person, another person who was there you probably don't-- never knew him, was Bill Pritchard. Bill was one of our undergraduates in Sydney in mech eng, and he'd gone on to... where did he do his PhD-- oh he went to Cambridge and did his PhD, that's right. And then he went across the Atlantic and he worked in various places.

McKinley:

And I think he worked on hole pressure effects as well, right?

Tanner:

He did, yeah. And he was a very, very careful and good worker. And so Bill Pritchard was there. But he died when he was about 50-something. He'd gotten some cancer. Yeah.

McKinley:

So anyway, were there other visitors at the same time? Because I know that there are a lot of people passing through the Rheology Research Center in those days.

Tanner:

Yeah, there was Dave Malkus but I don't know if he was there permanently.

McKinley:

He became permanent, at least. I don't know if he was then, but I know people like Meissner and Ken Walters and people came to visit --

Tanner:

They were before, before me I think, yes. But anyway, it was a really inspirational visit, and we left about the 10th of December, which is the right time to leave Wisconsin. (both laugh)

McKinley:

Or you don't leave until March, right?

Tanner:

Yes. (laughs)

McKinley:

And you took the whole family with you again?

Tanner:

No, this was I think Elizabeth and I just went together on that one.

McKinley:

Right. You've also had multiple sabbatical visits to Delaware. Shorter visits, and who was your host there?

Tanner:

Yeah. Well, to begin with, I guess Art Metzner organized it. And Mort Denn was there, at the first one. And Mort was very interested to learn about finite element technology at the time. So this was around... it must have been about '79-- '77. Something like that. Anyway, so Mort and I, we got on very well, and we published a paper with a man called Fisher who was a bit crazy. (laughs) He was a crazy graduate student. And then--

McKinley:

And that was on fiber spinning, I think, right?

[GM. “Initial Profile Development in Melt Spinning”, Ind. Eng. Chem. Fundamentals, 1980, 19 (2), pp. 195-197 (with R.J. Fisher, M.M. Denn)]

Tanner:

Yes, that's right. It was the swelling as you come out, because they got all this theory about fiber spinning, but they didn't know what the initial diameter ought to be. So that was what we did. And then... you're remarkably well-informed about what I've done. Anyway, so then the next time, there was a spot in mechanical engineering that I came to. I came to them twice, I think. And we had a really nice time at Delaware. Except my wife didn't like it. She thought it was a village. (both laugh) But anyway, so yes, we had several children with us at one point. There were two I think, and none for the second visit. But I gave a talk on hydrodynamic stability…a set of lectures, I mean. A course on it. And one of the people that sit in on the course Lynn Walker.

McKinley:

Really? Okay.

Tanner:

Yes. So that's how I met Lynn Walker.

McKinley:

That I didn't know. Okay.

Tanner:

Yeah. And then of course we... she was a very smart-looking young lady at that time, and we've remained very friendly over the time.

McKinley:

Fantastic. Okay so I know you were interested in that topic. I mean way back from earlier days, you'd done shear-wave propagation and things like that.

Tanner:

Yes, so anyway, after a while, what happened was... let's see if I... That was about the time when I had some health problems and I really couldn't go on any more visits for a year or two. So then I got back to normal and I...

McKinley:

Okay, so you mentioned a long time ago you got to know Ken Walters, I guess. Maybe at the first ICR meeting that you attended, but let's talk about your work with him, because I got to know you and Ken at the Newton Institute in 1996.

Tanner:

That's right. I remember you there. You had a baby or something.

McKinley:

We had a baby, yes. Yeah, we had our two children with us at the time.

Tanner:

Yeah. What I'm going to do is I wrote a paper for one of the, you know, a sort of a tribute to working with Ken on a book, on that book. So if I could find that, you can read it.

McKinley:

While Roger's looking for that, I'll say that book that he's referring to is Rheology: an Historical Perspective, which is in the Rheology series that I saw the "sausage-making" if you like, and it happened during the time of the Newton Institute, yes.

Tanner:

That was great. I don't know whether I can find this immediately, so we won't waste too much time, but I did write a note about what it was like working with Ken. And you know Ken is actually a bit of a slave driver when it comes to working on a joint project-- oh here we are. "With K.W. Through History," it's called here.

McKinley:

And where did this-- did this get published, or this is just a personal--?

Tanner:

I gave it at Lisbon in 2012, this one. And this was about how we got started. It was one of his casual remarks. He said, about 1992 we were in Brussels at the International Congress. He said, "Why don't we write a (laughs) book on the history of rheology?" So that was how it started. And so then we set up a plan and there were really quite interesting things to do. There was things we didn't, we couldn’t agree on.

McKinley:

Such as?

Tanner:

Well, I will read it out here, because it's just the way that one likes to write things. I write the possessive as Tanner's Tough Life, you see? With a comma “s”. And when the name ends in “s”, we should write Walters's. (laughs) Well he doesn't want to do that, he just wants to have a comma at the end you see. So we agreed to differ about all this, and that my chapters have the way I did it, he had his (laughs) the way he did it.

McKinley:

Okay and did an editor ever merge them, or did they stay that way?

Tanner:

They stayed that way.

McKinley:

So how did you divide up the chapters?

Tanner:

Well Ken had certain things he wanted to talk about. He wanted to talk about the battles with the Truesdell mob.

McKinley:

And I have to say, I enjoyed reading those, because it's a very different period than it is now, where everybody's quite friendly to each other. So I've enjoyed hearing about that.

Tanner:

I wanted to write about the beginning, and then I've been very obsessive with Robert Hooke, particularly. And I've been down to the Isle of Wight and seen where he lived and so forth. And it's quite interesting down there.

McKinley:

That I didn't know. I know that there's very few, if any, pictures of him…

Tanner:

There are no pictures.

McKinley:

…because Newton had them all destroyed.

Tanner:

There is no picture. And we think Newton did it. So I wrote that one and Ken wrote the one we mentioned about the battles with Truesdell, and then I think I did something on numerics. Well, I can probably tell you by looking at it. So roughly half and half it came out to be. And it was Ken's idea that we should interpolate with little...

McKinley:

Vignettes.

Tanner:

Vignettes. He'd gotten this idea from some religious thing he'd written, so that was how it happened.

McKinley:

Right. I have to say, I find that's a great way of illuminating history, by the personal touch.

Tanner:

Oh it is. It was a very good idea. And we all did it. And I think I wrote the one on microstructure. And then he wrote the one on rheometry. And then bits and pieces. Now, I did the one on computational rheology at the end. So it was a fairly evenly split thing, and then of course we were at Cambridge, and the Cambridge library really was very, really good.

McKinley:

This is what I remember. I remember seeing you come back from trips to the library with all sorts of things about Boltzmann or various other things that you found, and yeah.

Tanner:

Yeah the, of course the amazing thing is the way they filed the things in the library was absolutely lunatic. They filed the journals by the size of the journal. So that when the Journal of Rheology changed its size, it went up two floors above where it was. (laughs)

McKinley:

Well that's interesting, because we've changed its size again recently…

Tanner:

Yes!

McKinley:

… so I wonder if it's moved yet again.

Tanner:

Oh yes, yes. (laughs) Well assuming they still take paper copies.

McKinley:

I think that these days, yes, everything is electronic. Yeah. But since you mentioned the computational rheology, you've kind of seen that field evolve from the very earliest days, then.

Tanner:

Yes.

McKinley:

From, you said from your early days of stealing computer time on an IBM at Brown.

Tanner:

Yes that's right.

McKinley:

So, you went to the first Numerical Methods workshop.

Tanner:

Yes, I did.

McKinley:

Which was in Louvain, I guess. Or one of the first ones. It was either in Spar or Louvain. I think it was in Louvain. It was an IUTAM workshop.

Tanner:

It was an IUTAM workshop, but I thought that-- you know this workshop, the first one was at Brown.

McKinley:

Okay.

Tanner:

Must have been 1979, because it was after I went to Sydney, and it was Bruce [Caswell].

McKinley:

Bruce organized it, mmhmm.

Tanner:

And it was, there really wasn't-- there were really interesting problems to do. So that we, I think it was a very good series of meetings. And then we went to Louvain-la-Neuve and we had that big meeting there. And Dan Joseph was there, do you remember Dan? (laughs)

McKinley:

I do remember Dan, yes. Yes. I would like to have interviewed him, but it's too late sadly. But what are your memories of Dan?

Tanner:

I remember him getting out there, raving on about continuum mechanics and then all of a sudden the chairman said, "You've got one minute to finish off." And he said, "I'll just quit now." (laughs)

McKinley:

This is in the days of handwritten transparencies?

Tanner:

Yes!

McKinley:

Because I remember screeds from him, yes. Yeah.

Tanner:

Yeah. The champion of handwritten transparencies was Barry Bernstein. I don't... Art Metzner and I were sitting in the back of a... I think it might have been a Society of Rheology meeting. Anyway, Barry came out there and he was talking about a finite deformation project, and of course he had capital X's for the initial position and little x's for the current position. So he was writing this on a transparency as he was going, and then after a little while he stopped, and he looked at it, and then he said, "I think that's wrong." And his fat finger came out and rubbed out the big X's and the little x's and changed them around. (laughs) It's such a mess--

McKinley:

I think someone just sent us a handwritten Barry Bernstein manuscript, actually. I haven't seen it yet, but I need to look at it. I shall look for the small and big x's then, to see how that's going. But you've seen this field really evolve, and in fact you were just telling me you're off to the next meeting in this kind of series, in Portugal this summer, which is kind of still a numerical methods workshop.

[GM. The International Workshop on Numerical Methods in Non-Newtonian Flows (IWNMNNF); Organized by Fernando Pinho and held in Regua in July 2019.]

Tanner:

Yes. I'm out of it now, though. I'm going to give a talk on what people ought to be computing, because I really spent most of my last ten or 15 years doing experiments, really. And what the suspension community needs is to get a proper agreement between calculations and experiments. And there really isn't much. We've finally got the… if you've got a Newtonian matrix and you can get pretty good answers now, there's a bunch in France run by Elisabeth Lemaire. And Gallier is the lead author on this paper in the JFM. And they did some nice calculations about five years ago. And they agree very well with our experiments, which there are very few... you know, we got the old trough out of the--

McKinley:

I remember seeing a presentation of yours in this. And I was going to ask you, though, about the tilted trough. Which is I guess frequently known as Tanner's tilted trough.

Tanner:

Oh that was Bob Bird, who invented that, yes. Yes, well that turned out to be a very good way of measuring stresses in suspensions and we were able to get the normal stresses probably better than had been done before. And it agrees with Gallier's result, providing that you have a friction coefficient between the spheres of about 0.5. Whereas Mort Denn and [Roman] Mari, who really are very good people of course, but they used zero, one, and infinity for the--

McKinley:

For the coefficient?

Tanner:

For the friction coefficient. So zero's too small and you don't get much, and in fact, John Brady did all that stuff a long time ago. One is too big most of the time, so you get--

McKinley:

Too much shear thickening.

Tanner:

Too much sheer thickening and too much viscosity. And the infinity is, well, further off. So we've now gotten to the point where I think the Newtonian viscous model is okay. I mean, it agrees with experiments. With the non-Newtonian matrices, there's still a hell of a long way to go. So that's what we're doing now.

McKinley:

So you're doing experiments and simulations, or just experiments?

Tanner:

I'm not doing any more simulations. The person I work with who does simulations is Marco Ellero. You know Marco?

McKinley:

Yes, I do. Yes.

Tanner:

He's a very bright chap, and they're doing some very nice simulation work. He's moved to Spain now. He left South Wales and has gone to Spain. Yeah, I sent a paper to, a review of the field... Ralph Colby invited me to write a review, so I said I'll write one on suspensions of non-Newtonian matrices. So I sent it in on the 15th of December. Got some feedback from…reviewers on, around mid-February. And this bugger... You know Eric Shaqfeh, he's a bit of an awkward bugger, really. (both laugh)

McKinley:

I do know him well, yes. In fact, I'll be attending his 60th birthday party in August. Was he a reviewer, or...?

Tanner:

He was the reviewer. I suggested him. So, he's been holding up the publication of this thing because I disagree with him on a number of issues. And I don't think that's fair, because this is supposed to be a review. This is my view of his work. It's not his view of his work.

McKinley:

Right, right. And I think he's just published a review of his own in AIChE journal.

Tanner:

I know he has, because he asked me in a most outrageous manner if he could use one of my drawings. With all our data. And I said of course. (laughs) But he's, you know, he's just not a gracious sort of person. He's rude. So I've pissed off him.

McKinley:

I see, okay. But it will appear eventually in Journal of Rheology?

Tanner:

Well I hope so. I mean next week, if I don't... See, the trouble is Roseanna is really a protégée of Shaqfeh's.

McKinley:

She's at Stanford.

Tanner:

She's at Stanford now. And Eric got her the job there basically. So I'm going to have to write to Ralph Colby and say, "Now look, I don't want Eric rewriting my work." (laughs) Just the last bunch of stuff he sent, I just wrote back and said, "I don't want to make anymore changes, because, because, because..." Anyway let's not talk about that.

McKinley:

Let's move on, right. Tell me instead about the Australian Society of Rheology.

Tanner:

Ah.

McKinley:

Because you, again, this is something you've seen from the earliest days. From literally its inception.

Tanner:

When I first came here in the 1960s, there was an Australian-- a New South Wales branch of the British Society of Rheology.

McKinley:

Okay.

Tanner:

And then--

McKinley:

That I didn't know even existed.

Tanner:

Well that's right. So that went on, then I went away to Brown, and then when I came back again, we thought of somehow vaguely that we would like to put in a bid for the International Congress, but you had to have a national society in order to do that.

McKinley:

I see. Okay.

Tanner:

So we created one.

McKinley:

So roughly when would this have been?

Tanner:

About 1985 or 6. No, it must have been before that. '83, because I went to Mexico to Balta’s… [Baltazar Mena]

McKinley:

Yeah, to Acapulco, which was '84.

Tanner:

Yeah, what a lovely place.

McKinley:

Yeah, it was before my time, but I've heard wonderful stories about it from rock bands to the traffic commute across the bay and various other things.

Tanner:

So, at that meeting, we put in a bid, and so the people that really generated, was David Boger and people at Melbourne. Probably Tam was in on it. But then the, I've forgotten who was the chair of the committee that was deciding the next venue, but he said... Well it was an Italian. It was probably...

McKinley:

Pino Marrucci probably, or Gianni Astarita

Tanner:

Gianni, I think it was. Gianni said, "We're not coming to Melbourne in the middle of winter. Why don't you move it to Sydney?" (laughs) So that's what we did.

McKinley:

I see. (laughs) Probably a smart move. Melbourne can be quite wet in the middle of your winter.

Tanner:

So we got the bid, and then of course I don't know if you...

McKinley:

I didn't attend. I was a young graduate student at the time.

Tanner:

Who came from your...?

McKinley:

Certainly Bob Armstrong came, and I think maybe some of the senior students. But it was a long way to go, so I know Bob Armstrong came.

Tanner:

It was about 400 people came and it was pretty good. We had a lot of troubles, of course. There's always one or two people that cause more trouble than the rest of it.

McKinley:

Okay. Maybe they should remain nameless? But there's always a few.

Tanner:

They shall remain nameless, but we had arranged some bus trips around the city for sightseeing on the Wednesday afternoon, and then there was a dinner. I think it was the same night. So anyway, on the way back in the bus, this Israeli woman who will remain nameless because I've forgotten her name, anyway, went up and said to the bus driver, "I want to get off at point X. Would you stop there?" And the bus driver said, "Sorry, madam, my orders are to go back to where we started the trip from and we don't do intermediate stops." So then she started screaming and yelling at him. (laughs)

McKinley:

Oh boy, okay.

Tanner:

And then the bus driver's union, which is quite a strong one, decided that they would not drive for our conference anymore. (laughs)

McKinley:

And you'd still got two days left of the conference.

Tanner:

And we've still got more trips to do. So luckily we had a very good contact, a travel organizer, and she rang around a lot of private companies and finally got enough buses for the next day.

McKinley:

Wow.

Tanner:

But no, and then this woman went off to Ayers Rock

McKinley:

Afterwards?

Tanner:

…Uluru. Afterwards, and fell down and broke her arm. (both laugh)

McKinley:

So it was just desserts, I guess.

Tanner:

So anyway, that's the kind of problems you get.

McKinley:

Okay. But certainly the ASR is going strong still. It seems, since those days.

Tanner:

It's very strong down in Melbourne. It's really died out here. I, to be honest, Gareth, I don't want to organize anything anymore. I've done my duty of organizing. And we're very thin on the ground up here. But Melbourne seems to be doing well. Yeah.

McKinley:

Yeah, so after, there's a tradition that after you've organized the conference you become the chair of the International Committee on Rheology for the next four years.

Tanner:

Yeah, I did, yeah.

McKinley:

So anything you remember being contentious or important back in those days? Now this would have been ‘88-92.

Tanner:

Yes I remember being the chair and I was severely rebuked by the committee because I had refused to pay the airfare for Nick Tschoegl from California to (laughs) to Sydney, because the silly bugger wrote to me and said, "Oh of course," he says, "you're going to pay my airfare, aren't you, from Los Angeles to Sydney, because I'm the secretary of the ICR." And I said, "No." (laughs)

McKinley:

And I believe Nick actually had some time in Australia, right, before he moved to California, he did bread dough work in Australia.

Tanner:

Yes, he worked for the Bread Research Institute and did interesting work and then he managed to persuade them that he should be sent to work with John Ferry to learn how to do G Primes and G Two Primes [ie G’ and G”] for dough. And then I don't think he ever came back again.

McKinley:

No, no.

Tanner:

So, he was a bit of a slippery dip and he wasn't my favorite person.

McKinley:

So you were reprimanded for that, huh?

Tanner:

Oh yes, the committee then insisted that the secretary have a piece of a report to put in the proceedings.

McKinley:

Right, now I think that's--

Tanner:

That still goes on.

McKinley:

Yes, yes. Gerry Fuller is now secretary.

Tanner:

Yeah, but Gerry would be a good secretary. He's very good.

McKinley:

Yes, yeah. He's very good and he's a non-voting secretary so that they're somewhat impartial. So, there's a representative from each country, but of course whoever has the secretary-ship, that's another vote, if you like. So there's become a tradition to make it a non-voting secretary, which is very good, I think.

Tanner:

Oh that's all right. Yeah.

McKinley:

So, you were awarded the first ASR Medallion, I think.

Tanner:

Yes.

McKinley:

And David Boger was the second one.

Tanner:

Yes.

McKinley:

So do you still have that, or?

Tanner:

Yeah, I know where it is. It might be up there.

McKinley:

It doesn't matter.

Tanner:

It's a huge thing.

McKinley:

It's a huge thing, yes. Yes.

Tanner:

It weights half a ton. Anyway, you can't hang it up, you can't wear it, you can't-- (both laugh) But I was very pleased to get it, nevertheless.

McKinley:

Yes. So but out of it, you've won numerous awards. I'm not going to list them all. But what's the one you have the best memories of?

Tanner:

I guess the BSR gold medal. That's the best.

McKinley:

And that was about 2000, I think? Or 2001 or something like that?

Tanner:

I can't remember. Yeah, just before 2000, yes. 2000, that's right. It was at the Cambridge meeting.

McKinley:

Oh, was it? Ah so it was awarded there

Tanner:

Yeah, yeah.

McKinley:

Okay. And that really is a gold medal, right? That you can wear in principle.

Tanner:

In-- I think it's in a drawer somewhere in the bedroom.

McKinley:

Yes. Wonderful so you also served as foreign secretary of the Australian Academy of Sciences. I love this idea of having a foreign secretary. This is in some sense an anachronism, but tell me what that entails.

Tanner:

Well the Academy of Sciences in Australia interacts with all the other academies around the world. And it has a very competent secretariat that does most of the work, but they always have a fellow to be the foreign secretary. And so you get to go on various trips, and the best one, the most useful thing I did when I was foreign secretary, was to go and visit Deutschland and set up the collaboration with the DFR, the German research organization. And we have an exchange program there. So that was the sort of thing we did. And then look after all the international connections, but the secretariat was very good.

McKinley:

Wonderful. So, I know you've done a number of consulting things, talking of setting up things. Like you did something for the government that was involved with the defense industry.

Tanner:

Yeah, we had quite a good contract with the Australian Defense to look into extrusion of things that go bang in the night, yes. (both laugh)

McKinley:

I think the euphemism is active materials or energetic materials? Or things like that, yes.

Tanner:

(laughs) That's right. So anyway, that caused-- that supported Craig Beverley's research. We tried to work out how to extrude... how to do calculations on extrusion of viscoelastic materials with a yield stress. It was very ambitious in those days.

McKinley:

Yes, indeed, yes. Still an open area.

Tanner:

Still an open area, but anyway that went on for a while. That was a good one. The best bit of consulting that I'm most proud of, I think, was with Exxon down in Texas. I was at Delaware at the time, just about to flit back to sunny Sydney. It was probably November or December.

McKinley:

Getting a bit grim there, mmhmm.

Tanner:

Yeah, and I got this phone call from them saying could I help them? Because they had this bearing problem, and it was not working. What it was is, they're making…blowing these bubbles. Film blowing. In order to blow the film, they have a pump to send the stuff through the die. The pump was lubricated with the material that was being pumped.

McKinley:

So it was essentially a gear pump or something like that.

Tanner:

It's a gear pump basically, and then it had big shafts about this size, and it was a huge affair. Anyway I said, "Look, I'm going back to Sydney in two days. I can't come to Texas to look at this." So anyway, I said I would look into it and I did. And they had already had about 20 consultants on this. See, the problem was that the bearings were seizing up after a certain time. They were just scoring metal on metal contact. And they had to tear it all apart and start again. And so what all the consultants had recommended was that they put water cooling through the bearings to keep it cool, because that looked like the real thing. Well my advice was quite the opposite, to heat it up.

McKinley:

To heat it up, uh-huh.

Tanner:

And it worked. (laughs)

McKinley:

And the explanation being...?

Tanner:

The explanation being that when it was cold, when you had cooled everything, the plastic did not stick to the metal, so it could not lubricate because it wasn't a fluid film anymore. But if you heated it, then it was back to fluid and...

McKinley:

Wetted better.

Tanner:

And it would wet and it would maintain the surface. That was a good thing. And I think I only charged them $5,000 for this. I should have charged them ten times as much.

McKinley:

(laughs) It kind of ties together your entire career nicely. It goes back to lubrication, right back at the very beginning.

Tanner:

Yes, it does. Well you know, and the other thing is that this work on suspensions is really friction and lubrication between the particles is so critical and the people that agree got me going on this. I guess it was Cates wrote a paper in Rheologica Acta, I read, and I felt well, gee, if he can make things shear-thicken in this way, I can make them shear-thin by doing the opposite. So that's what we've been doing.

McKinley:

I mean it's certainly become a very active area in the last couple of years.

Tanner:

Yeah, the last five years is--

McKinley:

And there's at least two camps with very different views on whether hydrodynamics plays the leading role or friction plays the leading role.

Tanner:

Well friction is so important. I mean yeah, you can about triple the viscosity of this by putting friction in or taking it out, even. And multiply it by three. So I'm now very much in the camp of those that believe in friction. I just saw a very good paper by Lobry and Lemaire and those people in France in JFM, but they're still not quite right. They overdo it, is the trouble with them. Have you ever read any of it?

[GM. https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/abs/shear-thinning-in-nonbrownian-suspensions-explained-by-variable-friction-between-particles/2B9D70F44D0D0BF9E698ED8CD0A11C75]

McKinley:

I don't know this work, no. So looking back, what's the favorite problems you've worked on? It probably varies with decades.

Tanner:

Well die-swell has been one of my favorite things. And it's easy to explain to people. I really enjoyed my time with the dough rheology as well, because we had good funding on that for six years.

McKinley:

From the Australian wheat …

Tanner:

Yeah, you know all about that stuff. And yeah, making the trough work was another thing I really liked. Of course, it's not that popular, not like the--

Elizabeth (in background):

Roger, did you know the time?

Tanner:

No, what time is it, darling?

Elizabeth:

Ten to one.

Tanner:

Oh, well, we'd better get off. We didn't use it for about 20 years, and then I had this student called Erwan Bertevas who really was-- a Frenchman, and he's very good. And I said to him, you know, we'd been doing these calculations on suspensions. I said, "Why don't we use a trough to try and measure some of this stuff?" So we did.

[GM. This work was published as: Dai, SC et al., J. Rheology 57(2), pp 493-510 (2013) “Viscometric Functions for Non-Colloidal Sphere Suspensions with Newtonian Matrices”]

Tanner:

Erwan was not an experimenter. He just couldn't get it. (laughs) Completely hopeless.

McKinley:

So, is this all the original trough?

Tanner:

Yeah.

McKinley:

Or do you have a new and improved trough? Or is it still the original instrumentation?

Tanner:

This is the one we built in 1975.

McKinley:

Still going.

Tanner:

Still going.

McKinley:

And where does it sit?

Tanner:

In a lab.

McKinley:

In Sydney?

Tanner:

Yeah.

McKinley:

Well, I hope that will stick around for a few more years, or will be preserved.

Tanner:

Yeah, the trouble is it's very expensive to run.

McKinley:

Because you need a lot of fluid.

Tanner:

You need three liters of fluid, and if you work out how much small particles you need to put in to get a 50% suspension, it cost about $500.

McKinley:

Yeah, well that's actually not that bad these days, but of course those particles can be very hard to disperse, and it's a few trillion particles I imagine.

Tanner:

Oh there's millions of them. It's amazing. Yes. So those are the things I really enjoyed. Yeah, computations, the experiments, and building models like the PTT model and dough model, and still trying to build models. I'm trying to get a model for suspensions, and I think we've got one that works all right for suspensions with Newtonian matrices, and then when you go to non-Newtonian, there are still too much unknowns.

McKinley:

Right.

Tanner:

Yeah, they're still there.

McKinley:

So what would your advice be for someone entering the field today?

Tanner:

Do some good computations.

McKinley:

Good computations.

Tanner:

And I think there are new ways of doing computations, like this SPH method that Marco Ellero does, and probably that's going to supersede all the old ways, because I'm really impressed by the way that they put this together. So I'm collaborating with Marco. We've got a paper for JFM. We've got two good, very good reviews, and then we got bloody Shaqfeh again. (laughs)

McKinley:

Uh-huh. So you've got to work on addressing that now.

Tanner:

Well we have addressed it, but we still haven't heard back, because Eric is a very bad responder when it comes to other people's... Did you know that?

McKinley:

I've heard that, yes.

Tanner:

(laughs) You've heard that. He's very bad. So yeah.

McKinley:

Well thank you for your time, Roger. I look forward to treating you to some lunch now.

Tanner:

Well you don't have to. I plan to treat you, because you're a Fellow of the Royal Society.

[GM. At the time of this conversation I (GHM) had just recently found out about my election to the Royal Society of London; hence Roger’s pointing out (during the interview) the various FRS colleagues he had worked with during the interview.]

McKinley:

Well thank you, thank you, I'm looking forward to that very much.

Tanner:

By the way, if you switched it off--