Numerical study on the flow field and particulate deposition in the asymmetric channels of a wall-flow diesel particulate filter

The wall-flow Diesel Particulate Filter (DPF) is an efficient exhaust gasaftertreatment device that reduces particulate matter emissions.Exploring the gas flow and particle deposition within the DPF isessential for advancing regeneration technology and optimizing itsstructural design. In the present study, the commercial computationalfluid dynamics (CFD) code ANSYS Fluent 15.0 is used to simulate thesoot laden flow field, whereas the trapping and in-situ deposition ofparticles are implemented through user-defined-subroutines. TheEuler-Lagrange method with user-defined functions is used to calculateparticle concentration distribution in porous media. The effects of factorslike inlet velocity, wall permeability, and particle size on particledeposition are systematically analyzed. Furthermore, the specific effectsof these factors on the flow field characteristics within asymmetricchannels are further explored. The study yields the following findings: anincrease in the inlet velocity markedly elevates the flow velocity withinthe channels, leading to a significant change in hydrostatic pressure, andthe resultant increase in static pressure difference between the inlet andoutlet channels thereby induces a higher through-wall velocity; higherwall permeability causes a more significant velocity rise in the inletchannel, thereby promoting increased particle deposition toward therear, with a maximum local deposition efficiency of 0.3 at a wallpermeability of 1?10-10 m2; enhanced inertia from larger particle sizesshifts the initial deposition point rearward, resulting in particles with adiameter of 2 ?m beginning to deposit at 0.3 times the channel lengthfrom the inlet.