A non-isothermal three-phase pollutant transport model, theoretical formulation and numerical applications

The purpose of this paper is the simulation of the non-isothermal flow and transport of contaminants in ground water systems. A system of six fully coupled non-linear partial differential equations were developed, in which the coupled flow of water, water vapour and heat is assumed to be governed by Philip and de Vries theory. The space discretisation is carried out using a modified Galerkin weighted residual finite element method with asymmetric shape functions. The resulting transient equations are then solved temporally by the generalised midpoint method, resulting in a system of six non-linear equations, in which the unknowns are the three fluid pressures, the temperature and the solute and gas NAPL concentrations. The accuracy and correctness of the model has been verified on a variety of isothermal and non-isothermal conditions. The results of subsets of problems analysed are shown to be in good agreement with analytical and other model simulators.