A numerical approach to the simulation of granular and multiphase flows

Multiphase flows have been an active area of research for decades. Despite this, dense compressible gas-solid flows are still poorly understood. A experiment developed recently [Wagner et al., Exp. Fluids 52, 1507 (2012)] is able to isolate these conditions through the use of a multiphase shock tube. However, the behavior of the flow inside the particle curtain remains unclear. The objective of this work is to use numerical simulations to understand the fluid dynamics at the particle scale in this flow regime. An immersed boundary method is used to model the solid particles. The particles are tracked in the Lagrangian reference frame and collisions are modeled using the hard sphere approach. The fluid phase is solved on an adaptive grid using the Parallel Adaptive Wavelet-Collocation Method. Detailed properties of the particle curtain are necessary for accurate simulations. Therefore, the discrete element method (DEM) is used to simulate the particle curtain in isolation. The model is first validated through comparison to a granular channel flow experiment. The mean and fluctuation velocity profiles are found to show good agreement. A fully three dimensional simulation of the particle curtain used by Wagner et al. yields information about the curtain\u27s volume fraction and velocity profiles. The results suggest that the volume fraction profile is not uniform as previously thought