Controlling wake flow by blowing external fluids through porous surfaces

Flow-induced vibration (FIV) is a common phenomenon in nature that occurs when flow passes over a bluff body. Under these conditions, the body’s shape creates separated flow over a substantial part of its surface.

FIVs can impact the structural integrity and performance of high-rise buildings, long-span cable-supported bridges, transmission lines, and offshore structures. In particular, cables and transmission lines, which are circular and cylindrical in shape, exemplify a cross section type of bluff body ubiquitous in civil and mechanical engineering designs.

Guo et al. demonstrated an effective method to control wake flows around a circular cylinder by blowing external fluids into the wake through a structured porous surface manufactured by 3D printing. They found wake flow characteristics can be greatly changed using this strategy and theorized aerodynamic forces may become effectively suppressed by the same means.

“While various kinds of flow-induced vibrations can be triggered when a bluff body is immersed in flows, such as wind and water, often the vibrations can be restrained or even eliminated if the characteristics of the surrounding flow are modified,” said author Haiyang Yu.

Installation of porous surfaces or coatings and active blowing are typical but distinctive flow control methods, with the former classified as a passive control method and the latter an active alternative. While previous research has focused on either one or the other, the current study combined them to effectively control cylinder wake flow characteristics with a wide flow control range and a steady, intuitive control process.

“We hope more and more combined methods can be investigated in depth in the future,” said Yu.

Source: “Wake control of a bluff-body via distributed jets over its surface,” by Mingqun Guo, Zan Wang, Haiyang Yu, and Donglai Gao, AIP Advances (2022). The article can be accessed at http://doi.org/10.1063/5.0093706 .