A SIMPLE COMPUTER-SIMULATION OF OSTWALD RIPENING

The coarsening of a polydisperse set of N particles is studied by comp uter simulation. The main steps of the simulation are the following: g eneration of a set of N (typically 20 000) particles according to an a priori model of the particle size distribution, and subsequent transf ers of molecules from one particle to another according to predetermin ed growth rules. As an application, we consider the Ostwald ripening p rocess. In this case, the exchange of molecules between small and larg e particles is governed by Kelvin's equation. The evolution of the ave rage particle radius and of the size distribution is studied both in t he stationary and nonstationary regimes. The typical characteristics o f the stationary regime predicted by the Lifshitz-Slyozov-Wagner theor y are recovered. For a more realistic initial log-normal size distribu tion, it was found that during an increase in average radius of about a factor of 4.3, the stationary regime was not yet attained. Results a re also reported for the combined effects of Ostwald ripening and memb rane resistance.