Simulation of Turbulent Flow in a Cyclonic Separator with Lattice Boltzmann Method

Abstract

A Lattice-Boltzmann Method (LBM) based very large eddy simulation (VLES) approach is presented and applied to simulate unsteady turbulent flow simulation inside a cyclone separator. LBM describes a fluid flow in terms of a discrete kinetic equation based on the particle density distribution function. The macroscopic flow properties are direct results of the moments of these particle density distribution functions. The effects of sub-grid turbulence are modeled by using two transport equations based on a revised renormalization-group theory, and realized through an effective particle-relaxation-time scale in the extended kinetic equations. This LBM based description of turbulent fluctuation carries flow history and upstream information, and contains high order terms to account for the nonlinearity of the Reynolds stress, which make it suitable to simulate the highly anisotropic unsteady turbulent flow inside cyclone separator. A wall-shear stress model is also used to reduce the near-wall resolution requirement. Flow solutions were obtained on a Cartesian grid system that resolves the boundary geometry exactly. Results compare well with experimental measurements and N-S based RSM (Reynolds stress model) predictions