Comment on "Walker diffusion method for calculation of transport properties of composite materials"

In a recent paper [C. DeW. Van Siclen, Phys. Rev. E 59, 2804 (1999)], a ran dom-walk algorithm was proposed as the best method to calculate transport p roperties of composite materials. It was claimed that the method is applica ble both to discrete and continuum systems. The limitations of the proposed algorithm are analyzed. We show that the algorithm does not capture the pe culiarities of continuum systems (e.g., "necks" or "choke points") and we a rgue that it is the stochastic analog of the finite-difference method.