EULERIAN-LAGRANGIAN APPROACH FOR MODELING OF FLOW AND TRANSPORT IN HETEROGENEOUS GEOLOGICAL FORMATIONS

This paper presents a new Eulerian-Lagrangian method for modeling flow and transport of passive solutes in heterogeneous porous formations. The physically plausible random velocity fields are generated by a geo statistical based model. The ability of the method to correctly reprod uce the velocity field statistics and to satisfy mass balance is teste d and demonstrated for the case of two-dimensional flow. The method is found particularly useful in dealing with large fields where numerica l, fixed grid methods such as finite difference or finite elements bec ome very demanding from a computational point of view. The transport p roblem is solved in a Lagrangian framework by the particle-tracking ap proach which uses a suitable grid refinement to correctly handle the v elocity fluctuation at any a priori defined resolution. The new method is employed to compute the probability distribution functions of the concentration and travel times and to investigate the limitations of e xisting methods for predicting concentrations.