The ISPH simulation of Rayleigh-Taylor instability and multi-phase flow within porous media

The present study applies the incompressible smoothed particle hydrodynamics (ISPH) method to simulate multi-phase flow instabilities, specifically Rayleigh-Taylor instability (RTI) and mixing in a sloshing tank, within various porous media. This study is the first numerical attempt to simulate RTI in diverse porous structures. Porous media are modeled with the non-Darcy approach based on linear and nonlinear factors. The Smagorinsky model is employed to implement turbulence stress. Two validation tests were performed to verify the effectiveness of the ISPH technique, the first evaluating pressure over still water in a tank, the second RTI in free fluid, and excellent agreement was obtained in both tests. The results indicate that porosity parameters play a crucial role in controlling the RTI phenomenon and mixing in the sloshing tank. Low porosity leads to high porous resistance, which significantly reduces RTI development and the mixing processes between the two fluids by hindering the interaction of the heavier and lighter fluids. This study shows the effectiveness of the ISPH method in handling complex interfaces in two-phase mixing flows within porous media.