The pressure drop evolution incurred in diesel particulate filters during the soot loading cycle is an important quantity of interest for the automotive industry. It is influenced by the shape of the filter, the pore geometry in the filter walls and even the precise soot deposition patterns inside these pores. We simulate and try to understand these processes by considering three different scales. On the scale of soot particles, simulations help determining packing densities of soot cake in the pores and on top of the ceramic filter media. On the scale of the filter media, simulations help determine depth and cake filtration parameters as function of deposited dust or time. Figure 1 illustrates the connection of rather free flow in the earliest stages of the filtration, the onset of clogged channels throughout the material and finally, cake filtration, with the typical S-curves observed in many measurements. In this case, comparison with experiments yields the viscous flow resistivity of the channel cake and surface cake.
With these parameters, also the depth and cake filtration on the scale of honeycomb structures can be simulated and understood.