Porous particulate film deposition in the transition regime

摘要: Abstract We examine the formation of particulate films via Langevin dynamic simulations monodisperse particle deposition onto flat substrates. In simulations, we consider inertia, thermal motion, and a constant advective force directing particles towards substrate. These conditions effectively mimic dust cakes during filtration, as well production nanostructured at outlet gas phase synthesis reactors. Parameterization equations motion shows that movement each depends only upon Kn D (the diffusive Knudsen number, proportional to particle׳s mean persistence distance its radius) χ F ratio translational energy velocity energy). Use these ratios is advantageous because one dimensionless number ( ) independent velocity, while second background pressure. This in contrast with traditionally employed Peclet Stokes numbers, both which are dependent The film structures resulting from quantified terms their porosities, results reported for over wide range (10 −3 –10 1 −4 3 ), areas 1000×1000 radii size, more than 10 6 deposited particles. For simulated deposit, three distinct regions observed: (I) region close substrate (within 50 primary radii), wherein porosity begins minimum increases value; (II) where this maintained (which on constantly increasing height encompassing majority after sufficient deposition; (III) outer region, still growing, II value unity, spanning less 100 most circumstances. A regression equation provided describe function II, facilitating priori predictions porosities parameters.