Toward numerical modeling of fine particle suspension using a two-way coupled Euler-Euler model. Part 1: Theoretical formulation and implications

This paper presents a two-way coupled Euler-Euler model to simulate the dilute suspension of fine particles. The goal is to develop a three-dimensional numerical model that is capable of replicating detailed features of particle-laden turbulent flow. In addition to the terms found in typical two-phase Euler-Euler models, the present formulation also accounts for the effects of added mass and pressure, which are crucial to solid-liquid systems in which densities for each phase are of the same order. This study derives various approximations with which to assess existing model formulations, namely solid-gas equations, equilibrium-state approximation, simplified Euler models, and hindered settling velocity. We then emphasize the deviation of the present simulation results from the equilibrium state, which is simulated by the single-phase approach. We investigate simple examples of the Rayleigh-Taylor instability induced by the suspension of fine particles, the results of which reveals the distribution of non-equilibrium particle inertia. We then examine its influence on the carrier flow. A comparison between the present two-phase model and single-phase approximation demonstrates the importance of the coupled pressure on the evolution of a single bubble induced by the particle-driven Rayleigh Taylor instability. (C) 2014 Elsevier Ltd. All rights reserved.