Fundamental study on the relationship between the apex and internal immobile area during sand heap formation

Abstract It is not clear the extent to which the behaviour of a single particle affects other particles or the entirety of granular materials. From the result of experiments on the angle of repose [1], The X-ray images taken before and after the sand heap was formed showed that there was an area in the sand heap where the particles had hardly moved since before the start of the experiment. It was also found that the position of the highest particle in the immobile area and the apex of the sand heap differed in the horizontal direction. Therefore, in this study, numerical simulations were performed a fundamental study. As a result, Granger causality was observed in the analysis results with a sidewall velocity of 0.03 m/s. Impulse response analysis was conducted on the instances where Granger causality was observed, allowing for the quantification of the magnitude, direction, and duration of the effects.