MODELING FLUID-FLOW AND TRANSPORT IN VARIABLY SATURATED POROUS-MEDIA WITH THE STOMP SIMULATOR .2. VERIFICATION AND VALIDATION EXERCISES

STOMP, a subsurface flow and transport simulator for investigating rem ediation technologies, described in the preceding paper, is tested aga inst simulation results from a published numerical code, MOFAT-2D, and against nonhysteretic and hysteretic data from three-phase flow exper iments. There is good agreement between the STOMP and MOFAT-2D simulat ions and between measured data and numerical results when STOMP is use d to simulate the experiments. However, there are some discrepancies b etween measured and predicted fliud contents. Discrepancies at low flu id contents are assumed to be a function of relative permeability-satu ration relations, and discrepancies near complete wetting-fluid satura tion are assumed to be caused by failing to account for a nonwetting-f luid entry pressure in the fluid saturation-pressure relations. Despit e the discrepancies, overall predictions of subsurface fluid behavior are good. These results suggest that STOMP may accurately forecast mul tiphase-flow behavior at a site when the site is adequately characteri zed and the model parameters are correctly calibrated to the site.