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Retention of rising droplets in density stratification
Summary
This laboratory study examined how density stratification in water affects the trapping and retention of rising oil droplets, with implications for understanding transport of buoyant particles in stratified water bodies. The physical principles studied here also apply to how low-density microplastics move through stratified ocean or lake water.
Timescales relating to the retention of oil droplets in a two-layer stratification are studied using laboratory experiments. It is shown that retention is primarily driven by the gradual recovery of a droplet from its velocity minimum to the upper-layer terminal velocity. The timescales associated with this process are governed by the Reynolds and Froude numbers, as defined by upper-layer characteristics.
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