Numerical investigation of the impact of washcoat distribution on the filtration performance of gasoline particulate filters

A three-step numerical model sheds light on the impact of three-way catalyst (TWC) washcoat distribution within the cordierite porous wall of a clean gasoline particulate filter (GPF) on its filtration performance. The model relies on (1) the numerical reconstruction of porous wall sections with various washcoat distributions and coating amounts, generated using a novel set of erosion/dilation-based procedures applied on segmented X-ray computed tomography data, (2) the computation of the flow field using the lattice Boltzmann method, and (3) the prediction of soot capture efficiency by solving the Langevin equation. The impact of washcoat distribution and amount on the pressure drop, permeability, filtration efficiency, and filter quality factor is systematically investigated. For a non-uniform washcoat distribution, an unexpected decrease in filtration efficiency with an increase in washcoat amount is explained and this highlights the complexity of the effects generated by the deposition of washcoat within the porous wall of the filter.