Quoted from: http://coda.oc.ntu.edu.tw/coda/research/diecast/index.html 

The DieCAST (Dietrich Center for Air Sea Technology) model is a z-level ocean and lake model patterned after the Sandia Ocean Modeling System (SOMS). The original DieCAST model is hydrostatic, incompressible, rigid-lid, partially implicit, and fully conservative. The numerical differences from the SOMS model stem only from using an Arakawa A grid instead of the Arakawa C grid used by SOMS. The DieCAST model is simpler and requires less computation per time step than the SOMS model. It is also stable with substantially longer time step. Both DieCAST and SOMS use higher order treatment of the generally dominat terms in ocean dynamics, i.e. pressure gradient and Coriolis. This leads to accurate and robust (stable with realistically small dissipation) models. In the latest version, the model includes the non-hydrostatic, free-surface, immersed boundary method (IBM) and two-ways coupling capabilities.