3D Macroscopic Model for Fluid Flow and Soot Deposit in Wall Flow Honeycomb DPF

This paper presents an original three dimensional model for fluid flow and soot deposition in the overall wall flow honeycomb DPF. First, hot-wire experimental velocity measurements carried out along the DPF outlet cross-section are shown to highlight the flow heterogeneity. Then coupled 1D local momentum and mass balance equations to describe a bundle of channels are proposed and discussed. The model is applied to simulate the loading of a bundle of channels. Two typical cases are considered to illustrate heterogeneity problems: (i) a transverse wall permeability gradient and (ii) the initial blockage of two entrance channels. In this latter case, the heterogeneity effect is found to be confined in the neighbor channels. Finally, a macroscopic form of this set of 1D local equations, obtained using a method of volume averaging applied on a cross-section filter element which consists of several unit elements, is described. First simulations of loading of a square cross-section DPF, having an initial spatial distribution of wall permeability, are performed. Results clearly show the heterogeneity distribution of both the flow and soot deposition through the DPF.