Cluster growth by diffusion-limited aggregation in shear flow

A two-dimensional square lattice computer model was used to study the cluster growth process by irreversible aggregation on the boundary of a shear flowing colloidal solution. The trajectories of the aggregating particles are determined by both a diffusion component and the streamlines of the flow. The streamlines were obtained by iterative solution of the Navier-Stokes equation. For zero drift (the case of simple DLA), the horizontal growth of the aggregates is symmetric, but even a very weak drift breaks down this symmetry considerably. The fractal dimensions obtained in the cases of zero and nonzero drift seem to be slightly different: 1.67 and 1.78, respectively.