A numerical method for modeling turbulent mixing across a stably stratified interface

A method is presented for numerically modelling turbulent mixing across an interface in a stably stratified fluid. The turbulence is modelled using a full second-moment stress/flux closure because of the anisotropy due to stratification, and the additional anisotropy due to the presence of the sharp interface. The numerical method utilizes an adaptive, moving-grid formulation of the governing transport equations, and solves for the movement of the interface implicitly with the solution of the transport equations. The implicit prediction of the interfacial movement is based on a special solution of the discrete scalar equation for the upper-most control-volume, which is assumed to reside partly in the non-active layer. Sample results are presented for the case of mixing due to ZMS turbulence and compared to similar experimental data. The computed results demonstrate the viability of the present method.