Large eddy simulation of flow past stationary and oscillating square cylinders

Abstract

Flow past stationary and oscillating square cylinders at Reynolds number 22,000 are studied using immersed boundary method (IBM) in large eddy simulation (LES), as the IBM is able to seamlessly simulate arbitrarily-moving bodies at an excellent efficiency. The square cylinders are forced to oscillate in a prescribed sinusoidal motion at reduced velocity 7.7, which corresponds to the resonance point. Two amplitude ratios $A/D$ = 0.05 and 0.1 based on cylinder height $D$ are studied. The accuracy of the current solver with the immersed boundary method is rigorously assessed against the reference data. To understand the effect of osculation motion on the flow and turbulence, aerodynamics of the oscillating cylinder is compared with that of the stationary cylinder. It is found that the oscillation motion reduces the spanwise correlation of flow field and triggers earlier reattachment on the side faces. Consequently, more chaotic surface pressure is generated downstream the reattachment point, and a smaller correlation is observed between upper and lower surface pressures. This helps to fully understand the interaction of turbulence and the flow-induced motion of a structure.

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ORCID for Zheng-Tong Xie: orcid.org/0000-0002-8119-7532

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