Experimental and computational investigations of nearly dense two-phase sudden expansion flows

Abstract The work investigates experimentally and computationally the effects of particle-to-particle collisions on the characteristics of the particle motion in a vertical downward flowing sudden expansion flow. The investigated flow is nearly dense, laden with spherical glass particles at 5% per volume. In order to simulate the particle-to-particle collision phenomena a model has been developed based upon the simultaneous Lagrangian tracking of all the particles which move inside the flow domain. Computational results with and without the particle-to-particle collision model are presented and compared to experimental data. The results establish flow regimes where particle-to-particle collisions become significant in that they modify the turbulent kinetic energy of the particles. It is shown that particle-to-particle collisions induce small variation of the fluid-particle slip velocities and reduce the turbulent kinetic energy of the dispersed phase mainly in the shear layer zone where the turbulent kinetic energy of the carrier phase attains maximum values.