Splashing drops

Article By:

Rudman, Murray Commonwealth Scientific and Industrial Organisation, Australia.

Last reviewed:2002

DOI:https://doi.org/10.1036/1097-8542.YB020855

When a drop of rain impacts a pool of water, a number of events occur within a fraction of a second. Capillary waves propagate outward from the point of impact, and a crater forms and collapses. One or more of the following events may also occur: a vortex ring may be propagated downward into the water; one or more air bubbles may be entrapped as the crater collapses; a jet of fine high-speed waterdrops may be ejected; or a thick jet that breaks into one or more large splash drops may be seen. The formation of small air bubbles during drop impact gives rise to the characteristic sound of rain and promotes the transfer of carbon dioxide (CO₂) from atmosphere to ocean. The small, high-speed droplets that form as a result of primary drop impact enhance the transfer of salt and microorganisms from the ocean to the atmosphere. Drop impact in shallow pools and puddles leads to erosion of the pool bottom, and the splash can distribute soil particles and plant viruses over a wide area. In metal smelting, splash is increasingly used to enhance heat transfer in the development of technologies to replace the blast furnace. In the galvanization of steel and spray coating with liquid metals, the effect of drop impact can influence the quality of the final product.

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