A time-splitting technique for the advection-dispersion equation in groundwater

In this paper a time-splitting technique for the two-dimensional advection- dispersion equation is proposed. A high resolution in space Godunov method for advection is combined with the RT0 Mixed Finite Element for the discret ization of the dispersion term. Numerical tests on an analytical one-dimens ional example ascertain the convergence properties of the scheme. At differ ent Peclet numbers, the choice of optimal time step size used for the two e quations is discussed, showing that with accurate selection of the time ste p sizes, the overall CPU time required by the simulations can be drasticall y reduced. Results on a realistic test case of groundwater contaminant tran sport confirm that the proposed scheme does not suffer from Peclet limitati ons and always displays only small amounts of numerical diffusion across th e entire range of Peclet numbers, (C) 2000 Academic Press.