Accumulation of Solid Particles in Convective Flows

Accumulation of solid particles suspended in unsteady convective flows is under theoretical investigation. The principal goal is to understand and interpret recent experiments by D. Schwabe [1,2]. Providing that volume particle concentration, nonisothermality, and relative size of particle are small, an effective single-fluid theoretical model is developed. The peculiarity of the obtained model is taking into account the distinction between fluid and particle inertia. This model is further applied to study particle accumulation in different flow setups: in a model oscillatory flow in a canal heated from below and subjected to the modulated gravity and in the Marangoni flow in a half-zone under microgravity conditions. These problems are investigated numerically by means of finite difference technique. We demonstrate, that the developed theoretical model properly describes generic features of particle accumulation in unsteady flows. Particularly, heavy particles tend to leave the centers of vortices, where the flow vorticity is maximal, and accumulate at their periphery. From numerical simulations in a floating zone, we try to clarify particle dynamics in Schwabe's setup.