Thermophoretic deposition of submicron particulate matter in fully developed turbulent square duct flow

Paper in proceeding, 2011

In the current work, the deposition efficiency of particles in the size range 5 nm - 1 μm is estimated in fully developed turbulent square duct flow (Re = 3000). The gas phase is solved for using the large eddy simulation (LES) technique, whereas the particles are tracked in a Lagrangian reference frame. The particle motion is assumed to be governed by the turbulence in the core of the channel. In the near-wall region, both drag and Brownian motion are taken into account. In addition, the explicit influence of the thermophoretic force on the particle deposition efficiency is obtained from simulations with and without thermophoresis being modelled. It is shown that thermophoresis has a significant effect on the extent of deposition of all particle sizes investigated. Most notable is the significantly enhanced deposition of intermediate-sized (20 - 300 nm) particles in the case of cold duct walls and hot gas flow. These findings are relevant for the development of new diesel particulate filters, where intermediate-sized particles could potentially be removed from the exhaust gases with a minimal pressure drop penalty if the thermophoretic effect could be properly employed.