On the Flow of Sand

[摘要] The sand flow through the wooden channel was investigated and found two modes of flow corresponding to the laminar and turbulent flow in hydrodynamics. The former is the flow as solid and the latter is the flow as liquid.There are a great number of examples which belong to the category of the dynamics of sand in natural phenomenon, say, land-slide, snow slip, skee and so on, but the literature is uttery wanting on this subject. Therefor it may be interest and important to study the dynamics of sand, so the author tried some experiments on the sand flow through the wooden channel for this purpose, and found following results.(1) The relation between the velocity and the inclination of the channel is not so simple as one may thought at first but it built up two ports A and B. The velocity inereases enormously for the slight increase of the inclination for A, while it is not so great for B.(2) The velocity of sand is proporsional to the, square root of the width of the channel for a given angle.(3) The experiment was carried out with various material and it was found following experimental formulæwhere η is equal to tan θc, and θc is the angle which separates A and B as part.(4) This two parts of the curve are concluded to be due to the differences of the motion corresponding to laminar and turbulent motion in hydrodynamics after the studies with camera & eyes.(5) Some of the results of the experiments can be explained by the assumption of two kind of flow above mentioned.

[学科分类] 大气科学