Numerical study of solid particles motion and deposition in a filter with regular and irregular arrangement of blocks with using Lattice Boltzmann method

摘要

In this investigation, motion and deposition of solid particles in regular and irregular structure filters have been studied. This study compares deposition efficiency of particles in two structures and investigates effects of Lift and Brownian forces on particles deposition. The laminar flow field in the filter is simulated using Lattice Boltzmann method and then motion of solid particles is investigated. The motion of particles is simulated using the Lagrangian method. The Lift, Drag, Brownian and Gravity forces affect particles motion. It is concluded that the Brownian force affects the motion and deposition of 0.01-0.1 mu m diameters particles in both of structures. A few numbers of the small particles are deposited on the blocks walls, but it is increased by decreasing Stk Number from 10(-5) to 10(-6) due to the effect of Brownian force on deposition of small particles. The Lift force has no significant effect on the deposition of particles in the investigated range of sizes, but ignoring this force increases the deposition efficiency of very small particles in both of structures of filters. The deposition efficiency has a rapid increasing for Stk Number greater than 0.1, due to the effect of inertial impaction on deposition of large particles. Regular filter has a more deposition efficiency for small particles (less than 15 mu m diameters) and irregular filter is more suitable for filtering large particles (more than 15 mu m diameters). The deposition efficiency on the surface of block in the channel containing a single block is more than regular and irregular structure filters. Finally, it is obtained that most of the particles deposited on the first block in the filter. (C) 2014 Elsevier Ltd. All rights reserved.