Joint impact of scaling and hysteresis on NAPL flow simulation

The hysteresis of capillary pressure versus saturation (P-S) relation is an important constitutive relation in multiphase flow, since the P-S relation is widely used to predict P-S relations in the simulation of the non-aqueous phase liquids (NAPLs). This work examined the performance of the scaling rule on predicting the P-S relationship and then studied the joint impact of the scaling and hysteresis on the multiphase NAPL flow simulation. Various experimental P-S values of distinct fluid pairs were compared with the scaled P-S curves using the scaling rule. The comparison indicated that the prediction of P-S is more accurate when the water-air P-S curve is used to scale other P-S curves. The joint impact of the scaling and hysteresis on the NAPLs flow simulation was then investigated by numerical simulation studies. The NAPL simulator was used to simulate the outcome of several scenarios based on a system with water-NAPL-air in a hypothetical sand tank. For both gasoline and trichloroethylene, the difference of the injected NAPL volume between no hysteretic and hysteretic simulations over a given time period was the smallest when the water-air P-S curve was used to scale other P-S curves. Simulation results of this study are valuable references for predicting the distribution of NAPLs.