Numerical simulation of the hydrodynamics and mass transfer in the large scale, rapid growth of KDP crystals. Part 1. Computation of the transient, three-dimensional flow field

Numerical simulations of the hydrodynamics and mass transfer involved in th e rapid growth of large KDP crystals (linear dimensions up to 60 cm and mas ses greater than 300 kg) have been performed. The simulations are fully thr ee-dimensional and time-dependent, and the computational geometry correspon ds very closely to the 1000-1 crystallizers currently in use at Lawrence Li vermore National Laboratory (LLNL) for the growth of KDP crystals for the N ational Ignition Facility (NIF). The Reynolds number of the flow is of orde r 10(5), and the Schmidt number is of order 10(3). The flow is turbulent an d dominated by flow separation from the rectangular corners of the rotating crystal and a secondary flow driven by Ekman boundary layers on the suppor t platform. The full three-dimensional structure of the flow field is descr ibed, but the major emphasis is placed on understanding the surface shear s tress distribution on the crystal, since it is critically involved in the p rocess of inclusion formation. The temporal and spatial evolution of the su rface shear stress and its effect on the surface morphological stability is compared for several different crystal sizes and rotation conditions. (C) 2001 Elsevier Science B.V. All rights reserved.