Development of FVHYDRO, a 3D Non-Orthogonal Unstructured Grid Finite Volume Hydrodynamic Model

The main purpose of this study is to develop an unstructured non-orthogonal grid hydrodynamic model that 1) does not subject to the very restrictive requirement of orthogonal grid and 2) can be solved stably and efficiently. The numerical algorithm mostly follows Casulli and Walters (2000) and Zhang et al (2004). The relaxation of the very strict requirement of orthogonality comes as a result of correction of the pressure gradient term due to the non-orthogonal nature of the grid based on non-orthogonal curvilinear coordinate fluid mechanics theory (Warsi, 1992). As a test case, the model is applied to the St. Lucie Estuary (SLE), a riverine estuary located on the east coast of South Florida. The non-orthogonal unstructured grid is adopted from a previous RMA model grid (Hu, 1999) with some modification in the North Fork area. Preliminary model results show the model can satisfactorily simulate the tide and salinity in the estuary.