Scale-Independent Model on Gravitational Dispersion of Particulate Suspension in Fractal Channels

Gravitational dispersion of solid particles in a liquid-filled channel can be seen in various engineering processes. However, it is known that the dispersion behavior is greatly influenced by properties of suspension and channel geometry. In this study, the gravitational dispersion behaviors of solid particles into a liquid-filled complex channel are examined experimentally. Particularly we focus on the dispersion of particles during the collective settling which occurs when the particle size is small and the concentration is large. In such conditions, the suspended particles form a finger-like blob and they behave as a continuum which is immiscible to surrounding fluid. We experimentally observed the collective settling in a fractal-shaped transparent channel. We also developed a scale-independent model on temporal change of the occupancy ratio of suspended particles in channels having fractal characteristics.