Numerical investigation of mixing layers using the discrete vortex method with the diffusion velocity model

The evolution of large vor tex structures and the nondimensional statistical quantities in a two-dimensional mixing layer are investigated by the discrete vortex method, in which viscous diffusion is treated by the diffusion velocity method Results indicate that continuous amalgamation among the large vortex structures is the primary factor leading to growth of the mixing layer. They agree well with experiments and show a strong capability to discover the self-similar property of mixing layers. Results also indicate that the over-estimation of root-mean-square velocity v' is attributed to the effect of three-dimensionality in actual flows, and is neglected by the two-dimensional discrete vortex method.