NUMERICAL-SOLUTIONS FOR SHAPE EVOLUTION OF A PARTICLE GROWING IN AXISYMMETRICAL FLOWS OF SUPERSATURATED SOLUTION

Numerical studies are performed to investigate the growth behaviors of a precipitate particle in the well-defined flows of supersaturated so lution with consideration of the isotropic and the anisotropic interfa cial free energies. For the well-defined flows, three types of axisymm etric flows are considered: uniform streaming flow, uniaxial straining flow, and biaxial straining flow. The numerical solutions are obtaine d on the numerically generated orthogonal curvilinear coordinate syste m, which is automatically adjusted to fit the boundary shape at any ti me. The initial value problem of particle growth is solved using a ful ly implicit first-order backward time differencing in order to ensure the numerical stability. The numerical solutions show that the convect ion effect results in higher local growth rate near the surface where the flow is incoming and lower local growth rate near the surface wher e the flow is outgoing. Due to the difference in local growth rate, an initially spherical particle evolves into a peach-like shape in the u niform streaming flow, an oblate spheroidal shape in the uniaxial stra ining flow, and a prolate barrel-like shape in the biaxial straining f low. (C) 1998 Elsevier Science B.V. All rights reserved.