CNS Meeting
Monday 07 October 2002, 11:00 AM, W505 Howey
Diffusivities and Front Propagation in
Sedimentation
Peter J.
Mucha
Continuum models for particles sedimenting in a fluid often assume
that the diffusivity is a local function of the particulate volume
fraction. Since the hydrodynamically induced diffusivity is a result
of the velocity fluctuations of particles, the recent identification
of particle density stratification as a controlling parameter for the
velocity fluctuations also extends to the diffusivities. In
particular, the stratification control strongly affects the
diffusivity in the vicinity of the falling sediment front between
particle-laden fluid below and clarified fluid above. The resulting
scaling for stratification-controlled diffusivities in creeping flow
sedimentation is presented and compares favorably with measurements
from dilute-limit particle simulations. Steadily-falling concentration
profiles for dilute sedimentation with these diffusivities are then
presented, and an extension of the model to higher volume fractions is
discussed.
![[FOSTERS BEER]](fosters.gif)