TY - JOUR
T1 - Molecular dynamics simulation study of friction force and torque on a rough spherical particle
AU - Kohale, Swapnil C.
AU - Khare, Rajesh
PY - 2010/6/21
Y1 - 2010/6/21
N2 - Recent developments in techniques of micro- and nanofluidics have led to an increased interest in nanoscale hydrodynamics in confined geometries. In our previous study [S. C. Kohale and R. Khare, J. Chem. Phys. 129, 164706 (2008)], we analyzed the friction force experienced by a smooth spherical particle that is translating in a fluid confined between parallel plates. The magnitude of three effects-velocity slip at particle surface, the presence of confining surfaces, and the cooperative hydrodynamic interactions between periodic images of the moving particle-that determine the friction force was quantified in that work using molecular dynamics simulations. In this work, we have studied the motion of a rough spherical particle in a confined geometry. Specifically, the friction force experienced by a translating particle and the torque experienced by a rotating particle are studied using molecular dynamics simulations. Our results demonstrate that the surface roughness of the particle significantly reduces the slip at the particle surface, thus leading to higher values of the friction force and hence a better agreement with the continuum predictions. The particle size dependence of the friction force and the torque values is shown to be consistent with the expectations from the continuum theory. As was observed for the smooth sphere, the cooperative hydrodynamic interactions between the images of the sphere have a significant effect on the value of the friction force experienced by the translating sphere. On the other hand, the torque experienced by a spherical particle that is rotating at the channel center is insensitive to this effect.
AB - Recent developments in techniques of micro- and nanofluidics have led to an increased interest in nanoscale hydrodynamics in confined geometries. In our previous study [S. C. Kohale and R. Khare, J. Chem. Phys. 129, 164706 (2008)], we analyzed the friction force experienced by a smooth spherical particle that is translating in a fluid confined between parallel plates. The magnitude of three effects-velocity slip at particle surface, the presence of confining surfaces, and the cooperative hydrodynamic interactions between periodic images of the moving particle-that determine the friction force was quantified in that work using molecular dynamics simulations. In this work, we have studied the motion of a rough spherical particle in a confined geometry. Specifically, the friction force experienced by a translating particle and the torque experienced by a rotating particle are studied using molecular dynamics simulations. Our results demonstrate that the surface roughness of the particle significantly reduces the slip at the particle surface, thus leading to higher values of the friction force and hence a better agreement with the continuum predictions. The particle size dependence of the friction force and the torque values is shown to be consistent with the expectations from the continuum theory. As was observed for the smooth sphere, the cooperative hydrodynamic interactions between the images of the sphere have a significant effect on the value of the friction force experienced by the translating sphere. On the other hand, the torque experienced by a spherical particle that is rotating at the channel center is insensitive to this effect.
UR - http://www.scopus.com/inward/record.url?scp=77953858333&partnerID=8YFLogxK
U2 - 10.1063/1.3436525
DO - 10.1063/1.3436525
M3 - Article
C2 - 20572733
AN - SCOPUS:77953858333
VL - 132
JO - The Journal of Chemical Physics
JF - The Journal of Chemical Physics
SN - 0021-9606
IS - 23
M1 - 234706
ER -