Mathematical modeling of spot dynamics in a stratified medium

The investigation of dynamics of mixed fluid spots in a stratified environment is of interest both for the study of the ocean fine structure and for the study of wake dynamics behind moving underwater objects. The paper is devoted to the construction of a physical and mathematical model for this problem. Salinity is used as the stratifying component. This model is described by the Navier–Stokes equations in the Boussinesq approximation. The problem is solved using a recent version of the splitting method by physical factors the finite difference scheme of which has a high approximation order, minimum scheme viscosity and dispersion, and, which is especially important for problems with large gradients of hydrophysical parameters, problems with a free surface and internal waves, the monotonicity property. Numerous test computations for the study of the influence of grid parameters on the results are performed. The results of comparison with analytical estimates, experimental data, and computations of other researchers are presented. By way of example, the dynamics of the salinity perturbation is discussed, which corresponds to the isophase lines describing the behavior of internal waves during the collapse of spots.