College of Engineering, Shizuoka University, Hamamatsu 432, Japan
(Received July 1, 1990, Accepted November 1, 1990)
Keywords: DLA fractal, Laplacian growth, Crossover
Abstract. Morphological changes in Laplacian growth are described in terms of crossover in statistical mechanics. The crossover phenomena between the diffusion -limited aggregation(DLA) fractal and nonfractals are analyzed by making use of a position-space renormalization-group method. The effects of the sticking probability, the finite viscosity ratio, and life time on the DLA are studied. The crossover from the dense structure to the DLA fractal is found to be induced by the sticking probability. The finite viscosity ratio induces the crossover from the DLA fractal to the dense structure. The crossover from the DLA fractal to the needle structure is induced by the lifetime effect.