CONSIDERATIONS FOR ROBUST COMPOSITIONAL SIMULATIONS OF SUBSURFACE NONAQUEOUS PHASE LIQUID CONTAMINATION AND REMEDIATION

A nonisothermal compositional model has been developed for examining n onaqueous phase liquid contamination and remediation scenarios. The go verning mass balance equations and constraints have been presented, an d various type of compositional formulations available have been exami ned, An efficient and robust formulation has been developed that addre ssed certain issues related to groundwater situations and overcomes nu merical difficulties encountered with previous formulations. The propo sed formulation collapses to that corresponding to the multiphase flow equation set when interface mass transfer is neglected, Numerical imp lementation of the formulation has been discussed, and example problem s have been presented for benchmark and verification, The present form ulation outperforms other currently used formulations for the isotherm al case studied and performs at least as well as its counterparts for the nonisothermal case. Characteristics of the simulator that hinder c onvergence for difficult problems have been identified, and directions for even further improvements have been noted.