Abstract
The major mode of transport of fine particles is the so-called Brownian motion, which manifests itself as “diffusion” in the macroscopic sense. When such diffusion occurs in the neighborhood of other objects, the increase in the drag on the diffusing particle affects the transport significantly. We present here a fundamental analysis of this phenomenon starting from the dynamics of the motion of the Brownian particle. The resulting stochastic equation of motion is transformed into a deterministic partial differential equation for the concentration of the suspended particles. This analysis offers for the first time a generalization of Fick's laws of diffusion for the colloidal particle and in that process provides an interesting application of a modern area of mathematical research.