Direct Numerical Simulation of a Temporally Evolving Incompressible Plane Wake: Effect of Initial Conditions on Evolution and Topology

摘要: Direct numerical simulations have been used to examine the effect of initial disturbance field on development three-dimensionality and transition turbulence in incompressible plane wake. The were performed using a new method for solving time-dependent, three-dimensional, Navier-Stokes equations flows with one infinite two periodic directions. uses standard Fast Fourier Transforms is applicable cases where vorticity compact direction. Initial disturbances fields examined combinations two-dimensional waves symmetric pairs 60 deg oblique at fundamental, subharmonic, sub-subharmonic wavelengths. results these indicate that presence subharmonic streamwise wavelength strong coherent three-dimensional structures. resulting rate-of-strain triggers growth intense fine scale motions. Wakes initiated fundamental develop weak structures, do not significant motions, even high Reynolds numbers. wakes which structures exhibit rates par experimentally observed turbulent wakes. only significantly lower late time rates. Preliminary studies an asymmetric wavelength, motions if are above angle approximately 45 deg.