Measuring the Stokes Velocity: the Dynamics of Monodisperse and Polydisperse Suspension Drops

Abstract

In the last decade, interest in deep-sea mining (DSM) has surged. The expansion of the global economy, advancement of technologies and the transition to more renewable energy solutions have caused an increased demand for metals like lithium and cobalt and rare earth elements. With land resources diminishing, there is a growing interest in the vast deposits that the deep sea holds in enriched mineral deposits. To evaluate the effect of DSM operations on sea life, it is important to study the dynamics of resettling sediment plumes and their effect on the ocean environment. A convenient method to do that is by studying the settling of suspended sediment material in small-scale lab setups. When discharging a suspension drop into a water tank, settling velocities can be several times higher than normal (Stokes) settling velocities, leading to an error in the estimation of particle properties. To make these experiments more useful and effective, it is thus important to study for what conditions settling velocities of suspension drops are sufficiently close to the Stokes velocity.