Evaluation of Instability of a Low-salinity Density-dependent Flow in a Porous MediumY. T. Habtemichael, R. T. Kiflemariam, H. R. Fuentes
Department of Civil & Environmental Engineering, Florida International University, Miami, FL, USA
Department of Mechanical & Materials Engineering, Florida International University, Miami, FL, USA
Seawater intrusion into coastal aquifers is usually modeled by using transport models that include account for the effect of variable-density on flow. Variable-density models can be validated with the Henry and Elder benchmark problems. However, when mixed convective flow is simulated under variable density conditions, it is susceptible to physical and numerical instabilities. The purpose of this work is to explore the development of instability during the migration of a NaCl plume in a homogenous medium that is initially saturated with freshwater. This is done by varying the Peclet (Pe) and Rayleigh (Ra) numbers to represent different discretization and density contrasts, while selecting a Courant number that gives numerical stability. The Darcy's law and solute transport models of COMSOL Multiphysics® software are used to model concentration distribution of the NaCl plume and sensitivity of the output to expected ranges of Pe and Ra numbers is evaluated.