Simpler-based procedure for numerical simulation of dynamic vortical characteristics of some turbulent flows

An unsteady numerical simulation based on the SIMPLER solution procedure with a strictly treated pressure solver is developed. This procedure greatly enhances accurate convergence in pressure as well as velocity in each iteration in the numerical simulation, so that it improves the prediction of the dynamic vortical characteristics of some turbulent flows in which pressure feedback constitutes the major contribution to the large-scale vortical behavior. The algorithm is used to investigate the coherent vortical structures and spectral evolution characteristics of jet flow and backward-facing step flow. The present numerical simulation can provide satisfactory predictions of vortex-shedding behaviors in jet and step flows without adding any artificial disturbance in the simulation. For cases of jet flows with and without excitation, the dynamic vortical evolution is predicted in good agreement with experimental observations and the well-known subharmonic evolution model. For turbulent backward-facing step flow with and without lateral mass bleed, satisfactory prediction of the time-averaged flow characteristics compared with experimental measurements is reached in the simulation. The complicated dynamic vortex-shedding process at the reattachment point of the backward-facing step flow is delineated based on the simulation results, and the results also provide evidence of the existence of both controversial shedding mechanism.