Numerical simulation of the flow around a circular cylinder in subcritical regime

The present study is to simulate the flow past a circular cylinder at Reynolds number of 5800, which is based on free-stream velocity and cylinder diameter. The cylinder is slighted heated and the amount of heat is small enough to be considered as a passive scalar. Due to its complexity, the flow around a circular cylinder is considered as a challenging problem for computational fluid dynamics (CFD) simulation. Reynolds-averaged Navier-Stokes (RANS) equations and large eddy simulation (LES) are two commonly used approaches in turbulent flow simulation. In this study, these two methods are both investigated by employing a CFD software - FLUENT. For two-dimensional simulation, the renormalization group k-ε model is used with enhanced wall treatment. Moreover, two dimensional LES is also tested, which reveals the necessity for three-dimensional LES computations. For three-dimensional simulations, computations with Smagorinsky-Lilly subgrid-scale model and dynamic subgrid-scale model are used. Phase averaging technique is employed to study turbulence structure in the circular cylinder wake. An instantaneous quantity is decomposed into a time mean component, a coherent component and an incoherent component [1]. After the triple decomposition and structural averaging, the coherent contributions to the Reynolds stresses and temperature variance can be analyzed. The reference phase for phase averaging is calculated for the time history of the lift coefficient CL. Both velocity field and temperature field are investigated and compared with the experimental measurements. (author)