Numerical simulation of FID hydrodynamics of protein crystallization

Recently, some of us have proposed predictive equations for the four diffus ion coefficients, D-ij, in a ternary system of hard spheres. These equation s have been tested successfully for some ternary systems of interest in pro tein crystallization: mixture of PEGs in aqueous solution, and the system l ysozyme-NaCl-H2O. These equations supply the tools for a correct coupled an alysis of the diffusion phenomena occurring in crystallization processes. U sing the previous approach for the dependence of the four diffusion coeffic ients on the solute concentrations, a numerical analysis of transport pheno mena in a model system that can simulate protein crystal growth has been ca rried out. The set of equations is based on the incompressible form of the two-dimensional and time dependent Navier-Stokes equations. The hypothesis of variable thermodynamic properties (diffusion and dynamical viscosity) an d the Bousinnesq approximation for the momentum equation have been consider ed. The study has been performed by means of a numerical code based on a fi nite difference method. The influence of the coupled diffusion has been eva luated at different gravity levels. (C) 2001 Elsevier Science B.V. All righ ts reserved.