TY - JOUR

T1 - Effect of small particles on the near-wall dynamics of a large particle in a highly bidisperse colloidal solution

AU - Bhattacharya, Sukalyan

AU - Blawzdziewicz, Jerzy

N1 - Funding Information:
J.B. would like to acknowledge the support of this work by NSF CAREER Grant No. CBET-0348175.

PY - 2008

Y1 - 2008

N2 - We consider the hydrodynamic effect of small particles on the dynamics of a much larger particle moving normal to a planar wall in a highly bidisperse dilute colloidal suspension of spheres. The gap h0 between the large particle and the wall is assumed to be comparable to the diameter 2a of the smaller particles so there is a length-scale separation between the gap width h0 and the radius of the large particle b h0. We use this length-scale separation to develop a new lubrication theory which takes into account the presence of the smaller particles in the space between the larger particle and the wall. The hydrodynamic effect of the small particles on the motion of the large particle is characterized by the short time (or high frequency) resistance coefficient. We find that for small particle-wall separations h0, the resistance coefficient tends to the asymptotic value corresponding to the large particle moving in a clear suspending fluid. For h0 a, the resistance coefficient approaches the lubrication value corresponding to a particle moving in a fluid with the effective viscosity given by the Einstein formula.

AB - We consider the hydrodynamic effect of small particles on the dynamics of a much larger particle moving normal to a planar wall in a highly bidisperse dilute colloidal suspension of spheres. The gap h0 between the large particle and the wall is assumed to be comparable to the diameter 2a of the smaller particles so there is a length-scale separation between the gap width h0 and the radius of the large particle b h0. We use this length-scale separation to develop a new lubrication theory which takes into account the presence of the smaller particles in the space between the larger particle and the wall. The hydrodynamic effect of the small particles on the motion of the large particle is characterized by the short time (or high frequency) resistance coefficient. We find that for small particle-wall separations h0, the resistance coefficient tends to the asymptotic value corresponding to the large particle moving in a clear suspending fluid. For h0 a, the resistance coefficient approaches the lubrication value corresponding to a particle moving in a fluid with the effective viscosity given by the Einstein formula.

UR - http://www.scopus.com/inward/record.url?scp=44849096171&partnerID=8YFLogxK

U2 - 10.1063/1.2917339

DO - 10.1063/1.2917339

M3 - Article

C2 - 18537444

AN - SCOPUS:44849096171

VL - 128

JO - The Journal of Chemical Physics

JF - The Journal of Chemical Physics

SN - 0021-9606

IS - 21

M1 - 214704

ER -