  A new computational method is presented to resolve hydrodynamic interactions
acting on solid particles immersed in incompressible host fluids. In this
method, boundaries between solid particles and host fluids are replaced with a
continuous interface by assuming a smoothed profile. This enabled us to
calculate hydrodynamic interactions both efficiently and accurately, without
neglecting many-body interactions. The validity of the method was tested by
calculating the drag force acting on a single cylindrical rod moving in an
incompressible Newtonian fluid. This method was then applied in order to
simulate sedimentation process of colloidal dispersions.
