Asymmetric vortex merger in two dimensions: Which vortex is ‘‘victorious’’?

Merger of two like-signed vorticity monopoles is the chief mechanism for the emergence and growth of vortices in 2-D turbulent flows. The merger processes in turbulent flows generally involve vortices of different size and vorticity amplitude. This normally causes one of the vortices to dominate. Results of a numerical survey are presented that determine which vortex is dominant or ‘‘victorious.’’ These results are obtained through the complementary use of a low-order Hamiltonian moment model and a high-resolution pseudospectral algorithm.