Abstract: A finite difference scheme is employed to solve the Navier Stokes and continuity equations for a 3 D temporally growing plane mixing layer. The physical mechanism for generation and development of streamwise vortices in the mixing layer is numerically investigated. Rayleigh's theory of centrifugal instability for inviscid axisymmetric flow is extended to analyze the two dimensional primary flows of the mixing layer. Accordingly, a dimensionless group Ray =-(r/υθ)/υθ/r is derived, where υθ is th...