The hydrodynamic force and torque on a bounded sphere in Poiseuille flow

The lattice Boltzmann (LB) method is used to study the hydrodynamic force a nd torque acting on a sphere held stationary between parallel plates in pre ssure-driven flow. This and associated flow configurations are explored in this paper. LB results are in excellent agreement with existing theory and numerical results for simple pressure-driven flow between parallel plates, for flow through a periodic medium of spheres [Zick AA, Homsy GM. Stokes fl ow through periodic arrays of spheres. Journal of Fluid Mechanics 1982; 115 :13], and for the force and torque acting on a sphere held fixed at the qua rter vertical position in a pressure-driven flow between parallel plates. I n the latter case, LB calculations reveal a screening effect caused by neig hboring periodic images of the test sphere. It is shown that the test spher e is hydrodynamically decoupled from its periodic images when separated by approximately 30 sphere radii. LB results for force and torque as a functio n of sphere height and flow cell height are also reported. Copyright (C) 20 01 John Wiley & Sons, Ltd.