Transient stratification force on particles crossing a density interface

Lilly Verso, Maarten van Reeuwijk, Alexander Liberzon

International Journal of Multiphase Flow · 2019

DOI: 10.1016/j.ijmultiphaseflow.2019.103109 arXiv

Particles Stratification Experiments Parameterization

Abstract

We perform a series of experiments to measure Lagrangian trajectories of settling and rising particles as they traverse a density interface of thickness h using an index-matched water-salt-ethanol solution. The experiments conﬁrm the substantial deceleration that particles experience as a result of the additional force exerted on the particle due to the sudden change in density. This stratiﬁcation force is calculated from the measurement data for all particle trajectories. In absence of suitable parameterisations in the lit- erature, a simple phenomenological model is developed which relies on parameterisations of the effective wake volume and recovery time scale. The model accurately predicts the particle trajectories obtained in our experiments and those of Srdi ´c-Mitrovi ´c et al. (1999). Furthermore, the model demonstrates that the problem depends on four key parameters, namely the entrance Reynolds number Re 1 , entrance Froude number Fr , particle to ﬂuid density ratio ρp / ρf , and relative interface thickness h / a . ©2 0 1 9 Elsevier Ltd. All rights reserved.

Funding

EU 675675