Joint Impact of Scaling and Hysteresis on NAPL Flow Simulation

Abstract

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.

Modelling Energy Dissipation Due to Soil-Moisture Hysteresis

“…This restriction can be removed by combining the algorithms of estimating hysteresis energy dissipation described below with the techniques of simulation of spatially distributed flows of multiphase fluids in soils such as the methods of NAPL flow simulation developed in [7,8]. The extension to spatially distributed systems is however beyond the scope of the present paper.…”

“…An important method in modelling multiphase flows with hysteresis is based on scaling rules which relate the capillary pressure vs saturation curves for one pair of fluids to that of another pair [7]. We note that this scaling technique can open a door to extending the results presented below to multiphase systems of different fluids with periodic and stochastic inputs.…”