Pressure drop across packed beds in the low Knudsen number regime

Diffusion deposition of aerosol nanoparticles in model granular filters

“…The drag forces of packings of gran ules calculated by numerical methods were in good agreement with the data of model experiments [3] and the calculations by the Kozeny-Carman formula [1]. Sometimes, the cell model is used, according to which a dense packing is considered to be a set of suspended granules uniformly distributed over the volume of a layer of granules [7]. In the case of high porosity pack ings, such as deposits of dust particles on frontal sur faces of aerosol filters, the packing densities of which may be as low as a few percent, the pressure drop is reliably determined in terms of the fan model [8], according to which a deposit of particles with a den dritic structure is approximated by a uniform fibrous structure.…”

Analytical Solution of Unified Flow Field for Multiple Fluid Collectors in Finite Knudsen Number Regime

“…Applying the boundary conditions (Eq. (7) and (8)) to the flow field yields the stream function solution in the low Kn region, as shown in Table 1, by the dimensionless formula (Lee et al, 1978). As noted from previous studies (Lee et al, 1978;Pich, 1986), the flow field reduces to the original Kuwabara flow field for the continuum regime…”

“…For this reason, the streamlines of the flow outside a fluid-collecting sphere pass around the fluid-collecting sphere more closely than those around a solid-collecting sphere. In order to allow for gas slippage at the solid collector surface, Lee et al (1978) applied the Maxwell slip boundary condition, which set the tangential velocity component of the gas proportional to the local tangential stress component. Under the slip boundary condition, the tangential stress of the gas at the collector surface is assumed to cause the gas to slide (or slip) over the surface, producing a frictional resistance equal, and opposite, to the tangential stress.…”

“…These flow fields were obtained from solutions of the creeping flow equations for a system of stationary spheres arranged in a staggered manner. Later, Lee et al (1978) derived the velocity field, taking into account the slip of the gas at the surface of individual grains, which was based on the zero vorticity model. Keh and Shiau (2000) showed the inertial effects on the relative motion of a spherical solid particle in a viscous fluid at small, but finite Reynolds numbers in the low Kn region.…”

Mechano-chemical effects in weakly charged porous media

“…From Maxwell's times, the electric conductivity of two phase system has been studied by using various assumptions about the system architecture [71][72][73][74][75][76][77][78][79][80]. From these publications, one can take the formation factor f. The Darcy coefficient, K, can be taken from the papers on the creeping flow through the systems of solid particles or capillaries [81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97].…”