Validity of diffusion-enhancement techniques applied to diffusion-limited aggregation and other diffusive growth processes

Large-cluster growth by diffusive processes has been made practical by a diffusion-enhancement technique introduced by Meakin [Phys. Rev. A 27, 604 (1985); 27, 1495 (1985)]. This technique has been questioned on the grounds that a variable diffusivity will change the flux of walkers at the surface of the cluster given any particular boundary conditions. We demonstrate that, carried out properly, diffusion enhancement does not modify the flux. Thus, enhanced diffusion yields the same growth equations that nonenhanced diffusion does.