Currently, most aerodynamic optimizations for square cylinders mainly rely on corner modifications, which sacrifice usable area. The configuration of retaining sharp corners with convex side surfaces preserves space while promising aerodynamic benefits, yet it lacks systematic experimental data on how curvature regulates aerodynamic and wake behaviors. Thus, the present study focuses on the aerodynamic characteristics and wake flow features of this specific configuration, aiming to quantify the influence of convex surface curvature on its aerodynamic performance and wake dynamics. Wind tunnel experiments were conducted on a standard square cylinder and three variants with different convex surface curvatures, integrating Particle Image Velocimetry (PIV) and pressure measurement systems. Experimental results show that modifying the convex surface curvature significantly alters aerodynamic performance and wake characteristics. Increasing convex surface curvature results in a gradual decrease in the Cp,mean<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$C_{p,mean}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>C</mi> <mrow> <mi>p</mi> <mo>,</mo> <mi>m</mi> <mi>e</mi> <mi>a</mi> <mi>n</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> and Cp,rms<InlineEquation ID="IEq2"> <EquationSource Format="TEX">$C_{p,rms}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>C</mi> <mrow> <mi>p</mi> <mo>,</mo> <mi>r</mi> <mi>m</mi> <mi>s</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> distributions on the sides and leeward face of the cylinder, with maximum reductions of 55.89 and 94.67% compared to the standard square cylinder. This modification decreases the aerodynamic coefficient and vortex shedding intensity, enhancing overall performance. Analysis of the time-mean statistics of the wake reveals that increasing the curvature radius leads to an expansion of low-speed regions in the wake, accompanied by a decrease in the distribution and intensity of high turbulent kinetic energy. This alteration in flow patterns contributes to reduced resistance and enhanced flow stability. Additionally, Proper Orthogonal Decomposition (POD) analysis indicates that the modification of convex surfaces can concentrate the energy of the dominant modes, forming a more compact flow structure.

Experimental investigation on the effects of convex surface curvature on the aerodynamics and wake characteristics of a square cylinder

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发表日期：

2026年3月2日

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Yanhua Liu,
Yi Xia,
Yuncheng He,
Yujie Liu

摘要

Currently, most aerodynamic optimizations for square cylinders mainly rely on corner modifications, which sacrifice usable area. The configuration of retaining sharp corners with convex side surfaces preserves space while promising aerodynamic benefits, yet it lacks systematic experimental data on how curvature regulates aerodynamic and wake behaviors. Thus, the present study focuses on the aerodynamic characteristics and wake flow features of this specific configuration, aiming to quantify the influence of convex surface curvature on its aerodynamic performance and wake dynamics. Wind tunnel experiments were conducted on a standard square cylinder and three variants with different convex surface curvatures, integrating Particle Image Velocimetry (PIV) and pressure measurement systems. Experimental results show that modifying the convex surface curvature significantly alters aerodynamic performance and wake characteristics. Increasing convex surface curvature results in a gradual decrease in the C_p,mean $C_{p,mean}$ $C_{p, m e a n}$ and C_p,rms $C_{p,rms}$ $C_{p, r m s}$ distributions on the sides and leeward face of the cylinder, with maximum reductions of 55.89 and 94.67% compared to the standard square cylinder. This modification decreases the aerodynamic coefficient and vortex shedding intensity, enhancing overall performance. Analysis of the time-mean statistics of the wake reveals that increasing the curvature radius leads to an expansion of low-speed regions in the wake, accompanied by a decrease in the distribution and intensity of high turbulent kinetic energy. This alteration in flow patterns contributes to reduced resistance and enhanced flow stability. Additionally, Proper Orthogonal Decomposition (POD) analysis indicates that the modification of convex surfaces can concentrate the energy of the dominant modes, forming a more compact flow structure.