The significance of the trapped kink in granular segregation pattern formation

In binary-size granular segregation, when the avalanche stops, the surface of the granular bed is raised upstream of the flow layer, forming a local wedge structure, called trapped kink, which is important for segregation pattern formation. In this paper, we established the relationship between the position distribution of trapped kink head and granular segregation patterns. The experimental result shows that the position distribution of the trapped kink head is a log-normal distribution. The core pattern appeared when the standard deviation of the distribution is smaller than 0.4. When the standard deviation of the distribution is larger than 0.4, the segregation pattern would be from the core pattern to the streak pattern. The position distribution of the trapped kink head is affected by factors, the repose angle and the avalanche time. This provides an important theoretical basis for describing the formation of the segregation pattern and improving the segregation model.