Coarsening of solid-liquid mixtures in a random acceleration eld

The eeects of ow induced by a random acceleration eld (g-jitter) are considered in two related situations that are of interest for microgravity uid experiments: the random motion of isolated buoyant particles, and diiusion driven coarsening of a solid-liquid mixture. We start by analyzing in detail actual accelerometer data gathered during a recent microgravity mission, and obtain the values of the parameters deening a previously introduced stochas-tic model of this acceleration eld. The diiusive motion of a single solid particle suspended in an incompressible uid that is subjected to such random accelerations is considered, and mean squared velocities and eeective diiusion coeecients are explicitly given. We next study the ow induced by an ensemble of such particles, and show the existence of a hydrodynamically induced attraction between pairs of particles at distances large compared with their radii, and repulsion at short distances. Finally, a mean eld analysis is used to estimate the eeect of g-jitter on diiusion controlled coarsening of a solid-liquid mixture. Corrections to classical coarsening rates due to the 1 induced uid motion are calculated, and estimates are given for coarsening of Sn-rich particles in a Sn-Pb eutectic uid, experiment to be conducted in microgravity in the near future.