A Comparison between Numerical Modeling Approaches for the Simulation of Gravity Currents

Abstract

Gravity currents (GC) caused by saline water propagating into freshwater bodies is an interesting phenomenon in environmental fluid mechanics that has received attention from several past investigations. Numerical modeling tools have been proposed in such investigations to predict the advance, mixing and spreading of these currents. While modeling studies focusing on the mixing of the current with ambient water often involve the application of the Navier-Stokes equations, the shallow-water equations (SWE) that are much less computationally intensive can also be used. SWE model targets advance of the front (e.g. velocity) and the general distribution of the dense fluid mass. An ongoing experimental investigation performed at Auburn University has compared observed gravity currents (GC) with predicted GC applying different modeling approaches, including the three-dimensional Environmental Fluid Dynamics Code (EFDC) and SWE model alternatives. The latter models, developed in the context of this study, have been developed using different strategies including nonlinear schemes based on Riemann solvers using Finite Volume Method. A comparison is performed between the EFDC and the SWE model predictions and corresponding experimental measurements. An assessment of the applicability of different modeling approaches is presented.