Interactions between subaqueous barchans and static objects*

Crescent-shaped dunes, known as barchans, can be found in different environments, such as deserts, rivers, and also on the surface of Mars and Titan. In nature, it is possible to observe dunes approaching large obstacles, such as oil risers (for underwater dunes) and even houses (for aeolian bedforms). In this experimental work, we investigated how subaqueous barchans interact with obstacles whose sizes are comparable to their own. We varied the dune and obstacle sizes, flow strength, and grain properties. As a result, we observed that subaqueous barchans can pass over, bypass, or even be blocked by an obstacle. We proposed a classification map in which the behavior of dunes depends on the relation between the obstacle and dune sizes, and the Stokes number. The results can shed light on how to predict the outcomes of dunes interacting with obstacles, and to design structures that do not disturb sandy terrains. The content of this presentation is based on [1].

[1] - Assis, W.R., Borges, D.S., Franklin, E.M., Barchan dunes cruising dune-size obstacles. Geophysical Research Letters, 50, e2023GL104125, 2023.