NOVEL EULERIAN FORMULATION FOR DILUTE GAS-PARTICLE FLOWS WITH AN OBSTRUCTION

Abstract

A novel Eulerian formulation for dilute gas-particle flows with an obstruction is developed by taking into consideration explicitly incident and reflected particles. Particles in a control volume are separated into two families, incident and reflected, each of which is assumed to move with approximately the same velocity. The drag force over a control volume is split into two components, one for the incident and one for the reflected particles, each of which can be physically consistently calculated using a standard formula. The particulate phase flow can be described equivalently by the composite family, which consists of incident and reflected particles. The particulate flow of incident particles is first evaluated by applying an outflow boundary condition at windward obstruction surfaces, and then the composite particulate flow is computed using the information of the incident particle solution. The novel formulation is implemented in the commercial computation fluid dynamics code, FLUENT, via User Defined Subroutines. The prediction of dilute gas-particle flows past a 45 ramp and a cylinder with afterbody employing our novel Eulerian formulation shows excellent agreement with the results predicted by the Lagrangian approach. The detailed analysis shows that the key mechanism in volved in our novel Eulerian formulation is the correctly treated drag force over each control volume. Our novel Eulerian formulation can provide a useful approach for studying erosion and deposition in coal-fired boilers.