The coarsening of a polydisperse set of N particles is studied by computer simulation. The main steps of the simulation are the following:  generation of a set of N (typically 20 000) particles according to an a priori model of the particle size distribution, and subsequent transfers of molecules from one particle to another according to predetermined growth rules. As an application, we consider the Ostwald ripening process. In this case, the exchange of molecules between small and large particles is governed by Kelvin's equation. The evolution of the average particle radius and of the size distribution is studied both in the stationary and nonstationary regimes. The typical characteristics of the stationary regime predicted by the Lifshitz−Slyozov−Wagner theory are recovered. For a more realistic initial log-normal size distribution, 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 are also reported for the combined effects of Ostwald ripening and membrane resistance.

The rank of the data transfer matrices is used as a quantitative criterion for the assessment of the degree of ill conditioning of the inversion of static, single-angle, and multiangle quasi-elastic light scattering (QELS) data for particle size distributions by intensity, number, and volume. It is shown that the simultaneous (constrained) inversion of three-angle and more angle data sets for distributions by volume can be well-conditioned. The inversion of QELS spectral data is hardly better conditioned compared to the inversion of correlation data. However it appears that spectral data require about 10 times slower sampling times in the data-collecting procedures. The inversion of static data for distributions by volume appears also to be well-conditioned.

The Ostwald ripening of alkane in water emulsions stabilized by the surfactant poly(ethylene glycol) monolaurate (PEM) was investigated. Surprisingly the measured ripening rates were significantly below the rate which can be predicted by the Lifshitz−Slyozov−Wagner (LSW) theory and decreased in the presence of surfactant micelles. A possible explanation of the effect of these micelles is that they withdraw oil from the continuous phase and hence slow the transport of oil from smaller to larger droplets.

The Ostwald ripening of alkane in water emulsions stabilized by the surfactant polyoxyethylene (20) sorbitan monolaurate (Tween 20) was investigated. For emulsions prepared in the presence of excess micellar surfactant the Ostwald ripening rate enhancements with surfactant concentrations over the theoretical predictions of Lifshitz, Slyozov, and Wagner (LSW-theory) are less than a factor 3. For emulsions prepared with low surfactant concentration, followed by surfactant addition to the already-formed emulsion, the enhancements are up to a factor of 20, with increasing surfactant concentration.