Nanoparticle motion trajectories and deposition in an inlet channel of wall-flow diesel particulate filter

A two-dimensional gas–particle two-phase flow model in an inlet channel of diesel particulate filter (DPF) has been developed. The interaction between the gas and the particle is treated as one-way coupling due to the extremely dilute particle concentration. The drag force, the Brownian excitation, and the partial slip are included in the particle motion equation. The particle motion trajectories for various particle source locations and various particle sizes are presented. The dependences of the velocity field of the channel on wall permeability and upstream velocity are evaluated. The effects of particle size, upstream velocity, wall permeability, Brownian motion, and partial slip on the particle deposition are investigated. The three dominant mechanisms, which are drag force, Brownian motion, and particle inertia, are analyzed deeply. These results demonstrate that the drag force always plays the most primary role in determining the particle motion and deposition. On the other hand, the effects of Brownian motion and particle inertia vary with Pe number and Rep* number, respectively. As Pe number and Rep* number increase, the effect of particle inertia enhances, while the effect of Brownian motion lowers. The predicted velocity field is compared with the results obtained from the classical one-dimensional model, and the computational pressure loss of DPF is compared with the experimental values. The reasonable agreements of the two cases are both observed.

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