Binary collision of barchan dunes

In nature, barchan dunes usually move in groups in most cases, and their sizes are roughly close to each other. A major cause of such stability is the binary collision among the dunes. Researchers have studied extensively the binary collision, and summarized several types of collision patterns; recently, a classification map of the binary collision pattern, based on the control parameters such as Shields number, has been established. However, in the abovementioned work, collision patterns themselves have not been parameterized. This experiment returns to the starting point of the study by only retaining the most important control parameter: the initial mass ratio of two dunes in collision, conducts a dual-color water tunnel experiment, and proposes two ways of parameterizing the binary collision pattern. Then, a monotonous smooth relationship between the initial mass ratio and the collision pattern is obtained, which is able to reveal the inherent property towards stability of a dune group . The data includes an XLS documenting the collision pattern versus the initial mass ratio for a total of 35 cases, 7 representative collision cases (GIFs and TIFF images), and 8 other selected GIFs.