We report that the splash created by a solid impactor moving into a bed of granular media depends sensitively on the temperature of the granular bed. Granules were poured loosely into an open-top container and then heated from below, and a metal ball was then dropped into the hot granular bed. High-speed video experiments reveal that the size and average velocity of the resulting granular splash both decrease significantly as the temperature increases. Complementary experiments show that the composition of the surrounding gas also strongly affects the splash dynamics but that the gas pressure and corresponding density have no significant effect. We interpret these observations in terms of two physical effects: the influence of the temperature- and composition-dependent gas viscosity on the ejecta drag force, and an enhanced static strength within the bed caused by thermal expansion of the granules. Taken together, the results indicate that temperature plays a greater role in granular splashing than previously suspected.

• Received 29 April 2020
• Accepted 16 October 2020

DOI:https://doi.org/10.1103/PhysRevFluids.5.114302