Integration of fully 3D fluid dynamics and geophysical fluid dynamics models for multiphysics coastal ocean flows: Simulation of local complex free-surface phenomena

Abstract

A modeling system is presented for simulation of multiphysics coastal ocean flows at scales from O (1) m to O (1,000) km, especially for high-fidelity simulation of local, complicated, free-surface phenomena. The system integrates the solver for incompressible flow on unstructured mesh (SIFUM) and the finite volume coastal ocean model (FVCOM) on the basis of domain decomposition. In this system, the former is built on the Navier–Stokes equations and simulates small-scale, fully three-dimensional phenomena in local flows, whereas the latter is based on the geophysical fluid dynamics equations and predicts large-scale, background ocean currents. The integrated SIFUM–FVCOM system is developed from a previous system consisting of a structured-grid model and an unstructured-grid model (Tang et al., J. Comput. Phys. 273, 2014), and it combines two unstructured-grid models and has the capability of dealing with free-surface phenomena and complex geometries in local flows. In the new system, SIFUM and FVCOM are two-way coupled via Schwarz iteration, and they march in time together as a single system. The SIFUM–FVCOM system performs as intended with regard to capturing physical phenomena (e.g., generation of dam-break wave and slashing of water at a structure), converging with grid spacing and time step, and permitting seamless transition of solutions for far and near fields. In addition, its prediction of benchmark flow problems matches well with analytical, computational, and experimental data. The system is able to simultaneously and directly simulate many multiscale, multiphysics, real-world phenomena that could not be handled before. Such capability is illustrated by its application to coastal flooding and the resulting impact on a coastal bridge and a beachfront house.