Cabin air filters are applied to prevent small particles such as pollen, fine dust and soot amongst others from being transferred into the interior (cabin) of a vehicle. The filter media often make use of the so called electret effect as means for achieving high filtration efficiency at low pressure drop. Thereby, electrostatic filtration effects are supplemented to the well-known mechanical collection mechanisms (such as inertia, diffusion,...). Besides the interference of several fiber-particle interactions (Coulombic attraction/repulsion, induced dipolar forces, image charge effects) particle-particle interactions potentially play an important role. However, this effect is completely neglected in previous research studies due to the high degree of complexity [1]. In this work, we present a detailed investigation of the particle behaviour in the inflow area and transition area to the filter media. For a precise description of the underlying physical procedures the simulation is based on a four-way coupling. This approach takes into account the reciprocal influence between the fluid flow and the particle motion as well as the interactions between single electrostatically charged particles. The software package ESPResSo [2] used in this work is based on a molecular dynamic approach and provides the advantage of efficient algorithms for the modelling of electrostatic interactions. In order to emulate the air flow, the molecular dynamic simulation is coupled with a Lattice-Boltzmann fluid. The presented talk focuses on the influence of the particle-particle interactions on the filtration performance. It is elaborated whether the fully coupled system is necessary in order to reflect reality more closely or the simulation can be simplified to reduce the degree of complexity and thus the computational costs.

REFERENCES [1] S. Rief, A. Latz, A. Wiegmann, “Computer simulation of Air Filtration including electric surface charges in three-dimensional fibrous micro structures”, Filtration 6.2, (2006). [2] A. Arnold, O. Lenz, S. Kesselheim, R. Weeber, F. Fahrenberger, D. Roehm, P. Košovan and C. Holm, “ESPResSo 3.1: Molecular Dynamic Software for Coarse-Grained Models”, Lecture Notes in Computational Science and Engineering, (2013).