K. Qu

An overset grid method for integration of fully 3D fluid dynamics and geophysics fluid dynamics models to simulate multiphysics coastal ocean flows

It is now becoming important to develop our capabilities to simulate coastal ocean flows involved with distinct physical phenomena occurring at a vast range of spatial and temporal scales. This paper presents a hybrid modeling system for such simulation. The system consists of a fully three dimensional (3D) fluid dynamics model and a geophysical fluid dynamics model, which couple with each other in two-way and march in time simultaneously. Particularly, in the hybrid system, the solver for incompressible flow on overset meshes (SIFOM) resolves fully 3D small-scale local flow phenomena, while the unstructured grid finite volume coastal ocean model (FVCOM) captures large-scale background flows. The integration of the two models are realized via domain decomposition implemented with an overset grid method. Numerical experiments on performance of the system in resolving flow patterns and solution convergence rate show that the SIFOM-FVCOM system works as intended, and its solutions compare reasonably with data obtained with measurements and other computational approaches. Its unparalleled capabilities to predict multiphysics and multiscale phenomena with high-fidelity are demonstrated by three typical applications that are beyond the reach of other currently existing models. It is anticipated that the SIFOM-FVCOM system will serve as a new platform to study many emerging coastal ocean problems.

Hydrodynamic Effects of Solitary Waves Impinging on a Bridge Deck with Air Vents

AbstractAir vents in bridge decks are considered one potential measure for mitigating risk of damage to coastal bridges caused by extreme storm surge because they may reduce hydrodynamic uplift loa...

Domain Decomposition for a Hybrid Fully 3D Fluid Dynamics and Geophysical Fluid Dynamics Modeling System: A Numerical Experiment on Transient Sill Flow

A modeling system is presented for prediction of multiscale and multiphysics coastal ocean processes, and a numerical experiment is made to evaluate its performance. The system is a hybrid of a fully three dimensional fluid dynamics (F3DFD) model and a geophysical fluid dynamics (GFD) model. In particular, it integrates the Solver for Incompressible Flow on Overset Meshes (SIFOM) and the Finite Volume Coastal Ocean Model (FVCOM) using a domain decomposition method implemented with Chimera grids. In the hybrid SIFOM–FVCOM system, SIFOM is employed to capture small-scale local phenomena, and FVCOM is used to simulate large-scale background coastal flows. Simulation of a transient sill flow demonstrates that, while its performance is promising, the hybrid SIFOM–FVCOM system encounters difficulties in correctly resolving the flow at current front where there is strong unsteadiness and thus it needs further improvement.

Evaluation of SIFOM-FVCOM system for high-fidelity simulation of small-scale coastal ocean flows

This paper evaluates the SIFOM-FVCOM system recently developed by the authors to simulate multiphysics coastal ocean flow phenomena, especially those at small scales. First, its formulation for buoyancy is examined with regard to solution accu- racy and computational efficiency. Then, the system is used to track particles in circulations in the Jamaica Bay, demonstrating that large-scale patterns of trajectories of fluid particles are sensitive to small-scales flows from which they are released. Finally, a simulation is presented to illustrate the SIFOM-FVCOM system’s capability, which is beyond the reach of other existing models, to directly and simultaneously model large-scale storm surges as well as small-scale flow structures around bridge piers within the Hudson River during the Hurricane Sandy.