Numerical Modeling of Saline Gravity Currents Using EARSM and Buoyant k- Turbulence Closures

Abstract

Gravity currents are very common in nature and may appear in rivers, lakes, oceans, and the atmosphere. They are produced by the buoyant forces interacting between fluids of different densities and may introduce sediments and pollutants into water bodies. In this study, the hydrodynamics and propagation of gravity currents are investigated using WISE (Width Integrated Stratified Environments), a 2DV hydrodynamic numerical model. An Explicit Algebraic Reynolds Stress Model (EARSM) has been deployed and implemented in the hydrodynamic model and the simulated results have been compared against the laboratory measured values and the results obtained from the k- buoyant turbulence model originally implemented in WISE. The numerical simulations focus on three types of gravity currents generated for laboratory experiments, namely: Lock-exchange gravity current, buoyant wall-jet flow and intrusive gravity current. The simulated evolution profiles and propagation velocities are compared with measured values. The numerical model shows good quantitative agreements for predicting the temporal and spatial evolution of the gravity currents. The simulation results show better agreements in case of EARSM compared to buoyant k- turbulence closure. A sensitivity study also has been conducted to investigate the influence of the values of spatial and temporal increments on the accuracy of the prediction for the turbulence closures.

Keywords

• gravity currents
• turbulence modelling
• explicit algebraic reynolds stress model