2-DIMENSIONAL SIMULATION OF DENDRITE MORPHOLOGY

A computer simulation model is developed which is capable of simulating the growth of thermal dendrites in two dimensions. The thermal field governing the growth is determined by the non-steady state heat diffusion equation but is subject to random fluctuations whose level can be controlled. The anisotropy of growth velocity is shown up by simulating the growth on an appropriate finite grid and allowing growth only into the nearest neighbours. The growth can be followed in real time and the effect of material properties and process parameters can be determined. The morphology is quantified using the fractal dimension. The variation of the fractal dimension with material properties and process parameters is studied. A number of experimentally observed features are exhibited by the simulated results, including the transition to absolute stability at high velocities.