Theoretical expressions of the rolling velocity of a spherical sand grain and of the critical saltation force are derived for steady and uniform flow. In this process, the effect of turbulence and the existence of the viscous sublayer are fully considered. The expressions show fairly good agreement with the experimental results. The effect of turbulence is negligible in the rolling motion. However, it becomes important in the saltation motion. Moreover, more precise expression of the saltation motion of a spherical sand grain is derived by referring to Kishi's method.

抄録全体を表示