Lattice Boltzmann Simulation of Calcite Precipitation and Isotope Fractionation

The Lattice-Boltzmann (LB) method can be used to simulate aspects of chemical reactions such as vapor condensation or mineral precipitation from a fluid phase. It has the advantage of allowing the solute phase to evolve depending on local conditions rather than being specified, so that the controls on precipitated phase grain shape can be studied simultaneously with the controls on chemical compositions and growth rate. We have used the LB approach to simulate the precipitation of calcite from oversaturated water as an effort in developing methods for treating complex chemical reaction problems, including isotopic effects. The formation of calcite is a classic problem in diffusion and reaction-limited mineral growth. There are many complexities, but the process is attractive for modeling purposes because there is abundant information on reaction kinetics and the relationships between crystal morphology and growth conditions. In this paper we describe the LB approach used, address strategies for properly conserving mass at a surface of a growing 73"0?crystal?73"0?"08, the scaling of the calculations to the actual physical problem, and the conditions for growth of dendritic versus compact crystals.