Three-Dimensional Wake Transition and Hydrodynamics of a Circular Cylinder Near a Plane Wall

Investigators at Tianjin University have conducted a groundbreaking study on the three-dimensional wake transition and hydrodynamic forces of a circular cylinder placed near a plane wall. The research, funded by the National Natural Science Foundation of China, China Postdoctoral Science Foundation, and Tianjin University's Independent Innovation Funding, aimed to elucidate the mechanisms linking wall proximity, wake development, and force variations. By using direct numerical simulation at a fixed Reynolds number of 300, the researchers investigated a wide range of gap ratios (G/D = 0.2-infinity) with a constant boundary layer thickness (delta/D = 1.6).

The study has provided new quantitative insights into near-wall bluff body flows, revealing that four distinct vortex shedding regimes are identified-suppressed shedding, single vortex street, weak double vortex shedding, and quasi-isolated wake-each governed by the interplay between cylinder shear layers and the boundary layer. The research also demonstrated that hydrodynamic force analysis reveals that drag and lift fluctuations, as well as the Strouhal number, increase with G/D, stabilizing as wall effects diminish.

Key Takeaways:

• The three-dimensional wake transition and hydrodynamic forces of a circular cylinder near a plane wall are strongly gap-dependent, with two-dimensional flow dominating at small G/D (0.2-0.4) and increasing G/D inducing a progression from finer streamwise vortices to a mixture of large- and small-scale vortices.
• Near-wall interactions accelerate the transition to three-dimensionality compared to the isolated case.
• Four distinct vortex shedding regimes are identified, each governed by the interplay between cylinder shear layers and the boundary layer.
• Hydrodynamic force analysis reveals that drag and lift fluctuations, as well as the Strouhal number, increase with G/D, stabilizing as wall effects diminish.
• The evolution of streamwise velocity fluctuations near the wall captures the strengthening of local instabilities and their role in shaping wake structures and force responses.
• The study has provided new quantitative insights into near-wall bluff body flows and serves as a foundation for flow control and design optimization strategies.

Statistics:

• The study was conducted at a fixed Reynolds number of 300.
• The simulations spanned a wide range of gap ratios (G/D = 0.2-infinity) with a constant boundary layer thickness (delta/D = 1.6).
• The research included direct numerical simulation, spanwise Fast Fourier Transform, and autocorrelation on spatiotemporal lift fluctuations and streamwise vorticity.
• Four distinct vortex shedding regimes were identified.

Sources:

• Three-dimensional Wake Transition and Hydrodynamics of a Circular Cylinder Near a Plane Wall. Physics of Fluids, 2025;37(8).
• National Natural Science Foundation of China (NSFC).
• China Postdoctoral Science Foundation.
• Independent Innovation Funding of Science and Technology Innovation Leaders Cultivation "Qiming Program" of Tianjin University.
• Zhimeng Zhang, Tianjin University, State Key Lab Hydraul Engn Intelligent Construct &, Tianjin 300072, People's Republic of China.
• Cheng Lu, Chunning Ji, Xiangyi Zheng, and Md. Mahbub Alam.
• American Institute of Physics (AIP).
• Physics of Fluids (pof.aip.org/).