Compressible Flow Past Cylinders at Moderate Reynolds Numbers

The effects of compressibility on the flow past circular cylinders are not yet well understood, particularly with regard to their influence on flow dynamics, such as transition waves and the vortex shedding regime. A recent experiment by Nagata et al. [J. Fluid Mech., 2020] investigating a range of Reynolds numbers between 1000 and 5000 and Mach numbers between 0.1 and 0.5 revealed unusual behaviour at the highest Mach and Reynolds numbers. The studied flow regime is particularly sensitive due to the transition waves in the shear layers before they roll up to form von Kármán alternate vortices. The authors attributed the abrupt change in regime to possible oblique instabilities in the shear layers due to compressibility. The present paper aims to reproduce their experimental setup numerically in order to explain the observed flow dynamics and understand how compressibility can alter cylinder flow in the shear-layer transition regime.