CROSSOVER-BEHAVIOR DURING GELATION IN SHEAR-FLOW

Gelation in shear flow is studied using a two-dimensional, square latt ice cluster-cluster aggregation model. The model is similar to that pr oposed by Santra and Herrmann (1995); however, the rotation of the clu sters is to be taken into account. It was found that this modification of the model alters the behaviour of the aggregating system: under a certain length a(cr), the aggregation is isotropic and above a(cr) it becomes anisotropic. It is shown numerically and theoretically that th e crossover length a(cr) depends on the concentration as a(cr) similar to c(1/(D-d)), where d is the dimension of the space and D is the fra ctal dimension of the clusters.