ANISOTROPIC LAPLACIAN GROWTHS - FROM DIFFUSION-LIMITED AGGREGATES TO DENDRITIC FRACTALS

The statistical properties of anisotropic diffusion-limited aggregates (DLA) grown in a strip are investigated. The mean shape of these aggregates being related to the corresponding smooth Saffman-Taylor solutions, a finite-size scaling analysis is applied. This scaling description shows that the anisotropy-induced crossover from isotropic DLA clusters (D(F) = 5/3) to dendritic fractals (D(F) = 3/2) is actually contained in the continuous shape transition of the stable solution, from isotropic fingers of relative width lambda = 0.5 to lambda = 0 needlelike fingers.