This study numerically evaluates the hydrodynamic drag force exerted on a porous sphere moving through a Newtonian fluid towards an impermeable flat plate at a Reynolds number ranging from 0.1 to 40. The sphere is assumed to be highly porous, whose interior flow field is modeled by the combined Darcy-Brinkman model. The surrounding fluid how field is governed by steady-state Navier-Stokes equations. When the flee permeability is rather high, which is common for sludge flocs, no boundary layer separation occurs in the after-sphere region at large Reynolds numbers. The drag force thereby adheres to a Stokes' law like relationship.