Simulation of Particulate Matter Structure Detachment from Surfaces of Wall-Flow Filters for Elevated Velocities Applying Lattice Boltzmann Methods

Abstract

Rearrangement events in wall-flow filters lead to the formation of specific deposition patterns, which affect a filter’s pressure drop, its loading capacity and the separation efficiency. A universal and consistent formulation of probable causes and influence factors does not exist and appropriate calculation models that enable a quantification of respective influence factors are missing. In this work, a previously developed lattice Boltzmann method, which has been used with inflow velocities of up to 2 m s−1, is applied to elevated velocities of up to 60 m s−1. The particle-free flow, a single layer fragment and a deposition layer during break-up are investigated as three different scenarios. One goal of this work is a comprehensive quantification of the stability and accuracy of both particle-free and particle-including flows, considering static, impermeable deposition-layer fragments. A second goal is the determination of the hydrodynamic surface forces and the deduction of the local detachment likelihood of individual layer fragments. Satisfactory stability and accuracy can be shown for fluid velocity, fluid pressure and the hydrodynamic forces. When considering layer fragments, the parameter domain turns out to be limited to inflow velocities of 28 m s−1. It is shown that fragment detachment rather occurs consecutively and regions of no possible detachment are identified. The work contributes to an understanding of rearrangement events and respective deposition pattern predictions and enables potential optimizations in engine performance, fuel consumption and the service life of wall-flow filters.

Keywords

• wall-flow filter
• lattice Boltzmann methods
• porous media
• resolved particle simulations
• homogenized lattice Boltzmann method