Numerical simulation techniques of stratified flow by two-layer model and two-level model

For contaminated water transport phenomena, the vertical circulation induced by density current is very important mechanism. As computational techniques of stratified flow, there are two kinds of depth averaged two layer model, that is two-level model and two-layer model. The density difference generates the density currents, which induces vertical circulation. The vertical circulation patterns calculated by these models are different from each computational techniques. Because the treatments of vertical mixing between upper layer and lower layer waters of each model are different. This paper describes the characteristics of vertical circulation calculated by these models, and discusses the mechanisms of velocity distribution patterns of each model. As conclusion, two-layer model is applicable to stratified flow field computation, and two-level model is suitable for well-mixed flow field computation.