Modeling of Detailed Filtration Processes in DPFs via a User Subroutine Integrated 3-D CFD Code

Hoon  Lee, Argonne National Laboratory

ORAL PRESENTATION: A 3-D CFD model is developed for analysis of transient soot filtration processes in a conventional wall-flow type diesel particulate filter (DPF). The primary objective of this study is to quantitatively predict the local values of soot filtration parameters, such as porosity, permeability, collection efficiency, and deposited soot mass, within isotropically discretized computational domains in the multi-layered filter wall region. In general, commercial CFD codes do not generate structured mesh with ordered cell index nor allow mathematical recursive operation using standard user field functions. For these reasons, it is difficult for users to utilize the code in situations where complex algorithms are required. Therefore, we developed user subroutines with a C++ programming language and integrated into the CFD code using provided user interfaces to obtain local soot mass in each filter wall layer. The internal table function, coupled with the unit collector mechanism, is used to extract corresponding local collection efficiency at each time step and feed it back to the user code in order to calculate the local soot mass at the next time step. Results from this modeling work, including the evolution of porous wall filtration parameters over time, are visualized in 3-D along the channel wall, revealing correlations between flow pattern and soot deposition profile.

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