MODFLOW/MT3DMS-Based Simulation of Variable-Density Groundwater Flow with Simultaneous Heat and Solute Transport

SEAWAT is a finite-difference computer code, based on MODFLOW and MT3DMS, designed to simulate coupled variable-density groundwater flow and solute transport. This paper describes a new version of SEAWAT, which adds the ability to simultaneously model energy and solute transport. This is necessary for simulating the transport of heat and salinity in coastal aquifers for example. This work extends the equation of state for fluid density to vary as a function of temperature and/or solute concentration. The program has also been modified to represent the effects of variable fluid viscosity as a function of temperature and/or concentration. The viscosity mechanism is verified against an analytical solution and a test of temperature-dependent viscosity is provided. Finally, the classic Henry-Hilleke problem is solved with the new code and the results are compared with other published solutions.