ANALYSIS OF SPLIT OPERATOR METHODS FOR NONLINEAR AND MULTISPECIES GROUNDWATER CHEMICAL-TRANSPORT MODELS

Coupled solute transport and reaction models are computationally deman ding when multispecies, multidimensional simulations are considered. S plit operator methods provide approximate solutions to the reactive so lute transport problem that are both relatively efficient to compute a nd to construct. The transport and reaction operators are split into t wo separate computational steps. Split operator methods are introduced in the context of single species sorption to the soil, with an emphas is on the splitting errors that are induced. For standard two-step met hods, the splitting error is proportional to nt, the temporal step siz e of the numerical scheme. The alternating split operator scheme, in w hich the order of the operations is switched at succeeding time steps, apparently does not remove the splitting error for nonlinear reaction s, whereas it is removed for linear cases. The truncation error is ext ended to the case of two reacting species.