Lattice Boltzmann analysis of micro-particles transport in pulsating obstructed channel flow

Abstract

Dispersion and deposition of microparticles are investigated numerically in a channel in the presence of a square obstacle and inlet flow pulsation. Lattice Boltzmann method (LBM) is used to simulate the flow field and modified Euler method is employed to calculate particles trajectories with the assumption of one-way coupling. The forces of drag, gravity, Saffman lift and Brownian motion are included in the particles equation of motion. The effects of pulsation amplitude (AMP), Strouhal number and particles Stokes number (Stk) are rigorously studied on particles dispersion and deposition efficiency. Flow vortex shedding and particles dispersion patterns together with the averaged fluid–particle relative velocity and deposition efficiency plots are all discussed thoroughly. The results show that increment of pulsation amplitude enforces the vortices to form closer to the obstacle until their shape deteriorates as Strouhal number ratio (SNR) rises. The average recirculation length shrinks to its minimum at each studied Amp when SNR escalates to 2. Various behaviors are categorized for dispersion pattern of particles when Stokes number changes from 0.001 to 4. Deposition efficiency is indirectly related to Amp for Stk≤2 while for higher Stokes numbers (2<Stk≤4) they show direct relationship. Deposition pattern becomes rather independent of SNR at Amp=0.1. The grid independency test was performed for the LBM analysis, and simulation code was successfully verified against credible benchmarks.