Reduced Order Thermal Modeling of Data Centers via Distributed Sensor Data
Emad Samadiani, Yogendra Joshi, Hendrik Hamann, Madhusudan K. Iyengar, Steven Kamalsy et al.
In this paper, an effective and computationally efficient proper orthogonal decomposition (POD) based reduced order modeling approach is presented, which utilizes selected sets of observed thermal sensor data inside the data centers to help predict the data center temperature field as a function of ... [J. Heat Transfer 134, 041401 (2012)] published Mon Feb 13, 2012.
Comparison Between Thermal Conductivity Models on Heat Transfer in Power-Law Non-Newtonian Fluids
Botong Li, Liancun Zheng, and Xinxin Zhang
This paper endeavors to complete a numerical research on forced convection steady heat transfer in power-law non-Newtonian fluids in a circle duct. Incompressible, laminar fluids are to be studied with a uniform wall temperature. A hydrodynamic entrance length is neglected which allows establishing ... [J. Heat Transfer 134, 041702 (2012)] published Mon Feb 13, 2012.
Heterogeneity and Onset of Instability in Darcy's Flow With a Prescribed Horizontal Temperature Gradient
A. Barletta, M. Celli, and A. V. Kuznetsov
The aim of this study is the analysis of the onset conditions for the thermal instability in a fluid saturated porous medium. The investigation refers to an infinitely wide horizontal porous layer with vertical heterogeneity, such that the lower plane boundary is impermeable and thermally insulated ... [J. Heat Transfer 134, 042602 (2012)] published Mon Feb 13, 2012.
Numerical Results for the Effective Flow and Thermal Properties of Idealized Graphite Foam
Christopher T. DeGroot and Anthony G. Straatman
To simulate the heat transfer performance of devices incorporating high-conductivity porous materials, it is necessary to determine the relevant effective properties to close the volume-averaged momentum and energy equations. In this work, we determine these effective properties by conducting direct ... [J. Heat Transfer 134, 042603 (2012)] published Mon Feb 13, 2012.
Numerical Predictions of Hydrogen-Air Rectangular Channel Flows Augmented by Catalytic Surface Reactions
Ryoichi S. Amano, Mohsen M. Abou-Ellail, and S. Kaseb
Catalytic combustion of hydrogen-air boundary layers involves the adsorption of hydrogen and oxygen into a platinum-coated surface, chemical reactions of the adsorbed species, and the desorption of the resulting products. Re-adsorption of some produced gases is also possible. This paper presents num ... [J. Heat Transfer 134, 041201 (2012)] published Mon Feb 13, 2012.
Slip boundary for fluid flow at rough solid surfaces
Yongping Chen, Chengbin Zhang, Mingheng Shi, and George P. Peterson
A molecular dynamics simulation of slip boundary for fluid flow past a solid surface incorporating roughness effect as characterized by fractal geometry has been conducted with a focus on the origin of slip, fluid structure, and slip boundary flow. The results indicate that interfacial slip develops ... [Appl. Phys. Lett. 100, 074102 (2012)] published Mon Feb 13, 2012.
Transient flow of rarefied gas through an orifice
Felix Sharipov
A transient rarefied gas flow through a thin orifice is studied on the basis of the direct simulation Monte Carlo method. The mass flow rate and flow field are calculated as a function of the time in the transitional and hydrodynamic regimes with respect to the gas rarefaction. Two values of the pre ... [J. Vac. Sci. Technol. A 30, 021602 (2012)] published Mon Feb 13, 2012.
Layering Instability in a Confined Suspension Flow
M. Zurita-Gotor, J. Blawzdziewicz, and E. Wajnryb
We show [J. Fluid Mech. 592, 447 (2007)] that swapping (reversing) trajectories in confined suspension flows prevent collisions between particles approaching each other in adjacent streamlines. Here we demonstrate that by inducing layering this hydrodynamic mechanism changes the microstructure of su ... [Phys. Rev. Lett. 108, 068301 ] published .
Fluctuating hydrodynamics and turbulence in a rotating fluid: Universal properties
Abhik Basu and Jayanta K. Bhattacharjee
We analyze the statistical properties of three-dimensional (3D) turbulence in a rotating fluid. To this end we introduce a generating functional to study the statistical properties of the velocity field v. We obtain the master equation from the Navier-Stokes equation in a rotating frame and thence a ... [Phys. Rev. E 85, 026311 ] published .
Thermocapillary migration in small-scale temperature gradients: Application to optofluidic drop dispensing
Matthieu Robert de Saint Vincent and Jean-Pierre Delville
We experimentally investigate the thermocapillary migration induced by local laser heating of the advancing front of a growing droplet confined in a microfluidic channel. When heating implies an effective increase in interfacial tension, the laser behaves as a soft door whose stiffness can be tuned ... [Phys. Rev. E 85, 026310 ] published .
Transient-time correlation function applied to mixed shear and elongational flows
Remco Hartkamp, Stefano Bernardi, and B. D. Todd
The transient-time correlation function (TTCF) method is used to calculate the nonlinear response of a homogeneous atomic fluid close to equilibrium. The TTCF response of the pressure tensor subjected to a time-independent planar mixed flow of shear and elongation is compared to directly averaged no ... [J. Chem. Phys. 136, 064105 (2012)] published Fri Feb 10, 2012.
Intrinsic Stability of a Body Hovering in an Oscillating Airflow
Bin Liu, Leif Ristroph, Annie Weathers, Stephen Childress, and Jun Zhang
We explore the stability of flapping flight in a model system that consists of a pyramid-shaped object hovering in a vertically oscillating airflow. Such a flyer not only generates sufficient aerodynamic force to keep aloft but also robustly maintains balance during free flight. Flow visualization r ... [Phys. Rev. Lett. 108, 068103 ] published .
Oscillatory bubbles induced by geometrical constraint
M. Pailha, A. L. Hazel, P. A. Glendinning, and A. Juel
We show that a simple change in pore geometry can radically alter the behavior of a fluid-displacing air finger, indicating that models based on idealized pore geometries fail to capture key features of complex practical flows. In particular, partial occlusion of a rectangular cross section can forc ... [Phys. Fluids 24, 021702 (2012)] published Thu Feb 9, 2012.
Carbon nanotube-coated silicated soft magnetic carbonyl iron microspheres and their magnetorheology
Y. D. Liu and H. J. Choi
Core-shell structured magnetic microspheres were fabricated by coating the surface of silicated soft magnetic carbonyl iron particles with multi-walled carbon nanotubes using a facile layer-by-layer method involving an alternative sequential adsorption of positive and negative polyelectrolytes. The ... [J. Appl. Phys. 111, 07B502 (2012)] published Thu Feb 9, 2012.
Immiscible displacement of oil by water in a microchannel: Asymmetric flow behavior and nonlinear stability analysis of core-annular flow
Hooman Foroughi, Alireza Abbasi, Kausik S. Das, and Masahiro Kawaji
The immiscible displacement of oil by water in a circular microchannel was investigated. A fused silica microchannel with an inner diameter of 250 [mu]m and a length of 7 cm was initially filled with a viscous silicone oil. Only water then was injected into the channel. We describe our flow observat ... [Phys. Rev. E 85, 026309 ] published .
Direct numerical simulation of two-dimensional wall-bounded turbulent flows from receptivity stage
T. K. Sengupta, S. Bhaumik, and Y. G. Bhumkar
Deterministic route to turbulence creation in 2D wall boundary layer is shown here by solving full Navier-Stokes equation by dispersion relation preserving (DRP) numerical methods for flow over a flat plate excited by wall and free stream excitations. Present results show the transition caused by wa ... [Phys. Rev. E 85, 026308 ] published .
Pseudocompressible approximation and statistical turbulence modeling: Application to shock tube flows
Olivier Soulard, Jerome Griffond, and Denis Souffland
In this work, a pseudocompressible approximation relevant for turbulent mixing flows encountered in shock tubes is derived. The asymptotic analysis used for this purpose puts forward the role played by four dimensionless numbers on the flow compressibility, namely, the turbulent, deformation, strati ... [Phys. Rev. E 85, 026307 ] published .
Secondary instability in the near-wake past two tandem square cylinders
Choon-Bum Choi, Yong-Jun Jang, and Kyung-Soo Yang
Floquet stability analysis has been carried out to detect the onset of the secondary instability in the laminar flow past two identical square cylinders in tandem. Presence of a neighbouring cylinder alters flow topology, leading to change of stability characteristics. A parametric study has been pe ... [Phys. Fluids 24, 024102 (2012)] published Wed Feb 8, 2012.
Parametric study of cylindrical converging shock waves generated based on shock dynamics theory
Zhigang Zhai, Ting Si, Xisheng Luo, Jiming Yang, Cangli Liu et al.
In our previous work, the technique of generating cylindrical converging shock waves based on shock dynamics theory was proposed. In the present work, a further study is carried out to assess the influence of several parameters including the converging angle theta, the incident planar shock Mach num ... [Phys. Fluids 24, 026101 (2012)] published Wed Feb 8, 2012.
Observation of collision and oscillation of microdroplets with extremely large shear deformation
Tatsuya Yamada and Keiji Sakai
We measured the viscosity and surface tension of various liquids under large (~10 s) shear deformation. Oscillation of a 10-[mu]m size microdroplet is brought about by the head-on collision of two droplets. Since the Reynolds number is as small as 100, the motion of the liquid is stable and the dyna ... [Phys. Fluids 24, 022103 (2012)] published Wed Feb 8, 2012.
Thermal boundary layer profiles in turbulent Rayleigh-Benard convection in a cylindrical sample
Richard J. A. M. Stevens, Quan Zhou, Siegfried Grossmann, Roberto Verzicco, Ke-Qing Xia et al.
We numerically investigate the structures of the near-plate temperature profiles close to the bottom and top plates of turbulent Rayleigh-Benard flow in a cylindrical sample at Rayleigh numbers Ra=10 to Ra=2 x 10 and Prandtl numbers Pr=6.4 and Pr=0.7 with the dynamical frame method [Zhou and Xia, Ph ... [Phys. Rev. E 85, 027301 ] published .
Stability of double-diffusive double-convective miscible displacements in porous media
J. Azaiez and M. Sajjadi
The present study offers a paradigm on the stability of two-component miscible displacements in a homogeneous porous medium. The components have, in general, different mobility ratios, may diffuse at different rates, and are convected at different speeds. As a result, one of the components may lag b ... [Phys. Rev. E 85, 026306 ] published .
Extension of the momentum transfer model to time-dependent pipe turbulence
Esteban Calzetta
We analyze a possible extension of Gioia and Chakraborty's momentum transfer model of friction in steady turbulent pipe flows [Phys. Rev. Lett. 96, 044502 (2006)] to the case of time- and/or space-dependent turbulent flows. The end result is an expression for the stress at the wall as the sum of a s ... [Phys. Rev. E 85, 026305 ] published .
Thermocapillary motion of a slender viscous droplet in a channel
E. Katz, M. Haj, A. M. Leshansky, and A. Nepomnyashchy
We extend the previously developed low-capillary-number asymptotic theory of thermocapillary motion of a long bubble and a moderately viscous droplet in a channel [S. K. Wilson, The effect of an axial temperature gradient on the steady motion of a large droplet in a tube, J. Eng. Math. 29, 205 (1995 ... [Phys. Fluids 24, 022102 (2012)] published Tue Feb 7, 2012.
Fluid flows in a librating cylinder
Alban Sauret, David Cebron, Michael Le Bars, and Stephane Le Dizes
The flow in a cylinder driven by time-harmonic oscillations of the rotation rate, called longitudinal librations, is investigated. Using a theoretical approach and axisymmetric numerical simulations, we study two distinct phenomena appearing in this librating flow. First, we investigate the occurren ... [Phys. Fluids 24, 026603 (2012)] published Tue Feb 7, 2012.
Study of instabilities and transitions for a family of quasi-two-dimensional magnetohydrodynamic flows based on a parametrical model
S. Smolentsev, N. Vetcha, and R. Moreau
In this study, flow phenomena associated with inflectional and boundary-layer instabilities, as well as a mixed instability mode in quasi-two-dimensional magnetohydrodynamic flows in a rectangular duct are accessed with the help of a parametrical model, where the basic velocity profile with near-wal ... [Phys. Fluids 24, 024101 (2012)] published Tue Feb 7, 2012.
The Geometry of the Vapor Layer Under a Leidenfrost Drop. (arXiv:1202.2157v1 [cond-mat.soft])
ePrint arXiv http://arXiv.org/
Transport properties of dense deuterium-tritium plasmas. (arXiv:1202.2186v1 [cond-mat.mtrl-sci])
ePrint arXiv http://arXiv.org/
Nambu representation of an extended Lorenz model with viscous heating. (arXiv:1202.2210v1 [physics.flu-dyn])
ePrint arXiv http://arXiv.org/
Wind Energy and the Turbulent Nature of the Atmospheric Boundary Layer. (arXiv:1202.2245v1 [physics.flu-dyn])
ePrint arXiv http://arXiv.org/
Detonation re-initiation mechanism following the Mach reflection of a quenched detonation. (arXiv:1202.2318v1 [physics.flu-dyn])
ePrint arXiv http://arXiv.org/
Three-dimensional Lagrangian Voronoi analysis for clustering of particles and bubbles in turbulence. (arXiv:1104.2417v3 [physics.flu-dyn] UPDATED)
ePrint arXiv http://arXiv.org/