Abstract
We perform numerical simulations to examine settling and fluid transport by a pair of particles passing through a thin density interface of a two-layer fluid. As the particles settle through the interface, they deform the interface and carry upper layer fluid into the lower layer. This increased buoyancy hinders the particle settling such that the trailing particle collides with the leading particle at strong stratification and when the particles are nearly vertically aligned. When descending into the lower layer, the upper layer fluid detaches from the particles, returning upward within a wake whose width is on the order of two particle diameters. Due to the added buoyancy and the returning wake, particle settling is hindered and the trailing particle separates away from the leading particle when aligned within or near the wake of the leading particle. Meanwhile, the trailing particle re-entrains fluid detached from the leading particle. Consequently, the transport of upper layer fluid into the lower layer increased by up to 40% in the case of weak stratification.
7 More- Received 23 September 2020
- Accepted 30 March 2021
DOI:https://doi.org/10.1103/PhysRevFluids.6.044304
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