Far Downstream Wake Development with a Temporal Hybrid Method

Body-inclusive simulations are computationally expensive due to the fine grid resolution required to resolve the small scales around the body, and have a limited downstream extent. This work leverages the benefits of a body-exclusive temporal simulation, which allows for a coarser grid and much greater downstream distance so as to access the very far wake. Data from a body-inclusive circular disk wake sampled at a downstream location is used to initialize a body-exclusive large eddy simulation at a Reynolds number of 50,000. While classical scaling for defect velocity is U_D~x/D^-0.67, the initial power law is U_D~x/D^-0.8 possibly due to coherent structures associated with vortex shedding. There is a concomitant influence on the turbulent dissipation rate, which exhibits non-classical scaling with a dependence on the ratio of the global Reynolds number to the turbulent Reynolds number. The persistence of these coherent structures and their effect on the far-wake power laws of defect velocity and turbulent kinetic energy, and dissipation scaling are studied.