Hybrid Approaches for Simulation of Coastal Hydrodynamics --- Coupling of FVCOM/CFD and FVCOM/Shallow Water Model

As a consequence of many emerging issues such as the catastrophic Gulf of Mexico oil spill and potential coastline flooding due to sea level rise, there is an urgent need to develop our capabilities to predict small-scale and really 3D phenomena. In order to meet the need, we propose hybrid approaches and domain decomposition to couple different models designed for different physics and scales. In this presentation, a computational fluid dynamics (CFD) and FVCOM are coupled to simulate small-scale flow problems in coastal settings. The former is used to capture local flows, and the latter is employed to compute the large-scale background currents. In addition, a 2D shallow water model is coupled with FVCOM. In this situation, the 2D model is utilized to predict coastline flows and FVCOM is applied to simulate the deep water currents. The hybrid approaches are realized using two-way coupling and Chimera overset grids. Two numerical examples, which correspond to the two types of coupling, will be discussed. The first example is a thermal discharge from a multiport diffuser at the seabed, each of the ports is 10 cm in diameters, into estuary with sizes in hundreds of kilometers (Fig. 1a and b). The second example is flooding into lands and urban areas. The results clearly illustrate the feasibility and potential of the proposed approaches in prediction of multi-physics/multi-scale coastal ocean flows. Difficulty and unresolved issues will be discussed also. Fig. 1a FVCOM mesh. The discharge is located at mouth of Hudson next to NYC

Fig. 1b Simulated 3D thermal plume of the discharge