Climbing motion of grains in vibrating tubes with different geometries

- Grains can climb along an upright tube when it is vertically vibrating strong enough.
- Grains climbing is more sensitive to tube size rather than shape of tube cross-section.
- The climbing area in phase diagram narrows with increase of grain diameter.

By inserting a vibrating tube into a static grain layer, the grains can climb along the tube, which presents a new way to convey grains continuously. In this study, both tubes with different sizes and cross-section shapes are used to probe the effect of geometry on climbing motion of grains. Under same vibration strength, grains in small diameter tube can climb directly into an equilibrium height. The grains in large diameter tube can't climb directly. However, if enough grains are initially filled in the tube to a certain height, the grains can climb much higher. The grain climbing is more sensitive to the tube size rather than shape of tube cross-section. With same tube diameter, the climbing motion becomes difficult with increase of grain diameter. Consistent with the experimental results, a model based on force analysis is presented.

By inserting a vibrating tube into a static grain layer, the grains can climb along the tube, which presents a new way to convey grains continuously. In this study, both tubes with different sizes and cross-section shapes are used to probe the effect of geometry on climbing motion of grains. Under same vibration strength, grains in small diameter tube can climb directly into an equilibrium height. The grains in large diameter tube can't climb directly. However, if enough grains are initially filled in the tube to a certain height, the grains can climb much higher. The grain climbing is more sensitive to the tube size rather than shape of tube cross-section. With same tube diameter, the climbing motion becomes difficult with increase of grain diameter. Consistent with the experimental results, a model based on force analysis is presented.204