Numerical simulation of unsteady motion in a turbulent mixing layer

Unsteady motion in a two dimensional turbulent mixing layer is simulated numerically. The time averaged Navier-Stokes equations for mean flow are used ; the eddy viscosity model for turbulence is employed. The velocity fluctuation with the maximum spatial amplification rate is obtained by linearized calculation. The flow fields with the fluctuation excited by disturbances added at a fixed point with one, two, or four frequency components are calculated by the use of the finite difference approximation. Some of the features observed experimentally are reproduced, interpreted in terms of wave, and correlated with the results of the linearized calculation.