Modeling density-dependent flow and transport

There are a large number of problems in subsurface flow and transport where the density of the fluid depends on solute concentration. In some cases, for example, leachates from landfills and coastal saltwater intrusion, the density variations are relatively small (<5%). For a few cases, such as flow in the vicinity of salt domes and seepage from saline lakes, the densities are extreme (>20%) but the density differences remain relatively small (similar to 10%), Experience in predicting flow and transport in situations where fluid densities vary from 1000 to 1200 kg/m(3) is limited. Such cases present a severe challenge for numerical models. In this paper we present the results of preliminary simulations of density-dependent problems (Henry's saltwater intrusion problem and Elder's free convection problem) with the widely available FEMWATER computer code. Preliminary results of FEMWATER simulations for deep well injection of brine and the sinking of dense plumes beneath brine ponds are also discussed.