A new classification for barchan-barchan interactions

Abstract:

We investigate experimentally the different types of short-range interactions occurring between two barchan dunes and which physical aspects govern them. The experiments were conducted in a water channel of transparent material where controlled grains were poured inside, forming pairs of granular piles in both aligned and off-centered configurations. Afterward, a given water flow was imposed, forming a pair of barchan dunes that interacted with each other. In our experiments, different grain types (diameter and density), pile masses, distances and water flow rates were used, and a high-definition camera acquired images of the bedforms. We observed five different patterns for each configuration (aligned or off-centered), and propose a classification map that depends on the ratio between the number of grains of each dune, Shields number and barchans alignment. Our results shed light on the barcanoid forms and size regulation of barchans found in water, air, and other planetary environments