短顆粒鍊在垂直振動場下的水平運動行為

Abstract

我們將短顆粒鍊置於可讓其作繞行與垂直運動的準二維環形軌道中，施加垂直振動場於其上，同時以兩台正交的攝影機側錄顆粒鍊的運動。我們發現，短顆粒鍊在垂直振動場下的水平運動與其形狀有密切的關聯：當顆粒鍊在震動週期中維持棒狀均勻地直上直下時，其位移為緩慢的隨機漫步；當顆粒鍊在震動週期中一端翹起時，其會沿著翹起端的方向以定速前行；而當顆粒鍊在震動週期中兩端皆翹起時，其運動為超擴散運動，且其週期與週期間的運動有相當程度的關聯性。此外，顆粒鍊三形態的水平運動特性隨著實驗控制參數的改變大致相同。

We put a short granular chain in a qusai-2D circular channel and apply a vertical sinusoidal vibration on it. We set up 2 side-viewing cameras with orthogonal orientation to record the motion of the chain and discover that the horizontal motion of a short granular chain is closely related with its shape in vibrating cycles. When the chain keeps rod-like shape during vibration cycles, it behaves like small step random walk; when one of the ends rises up during vibration cycles, the chain moves ballistically; when both of the ends rise up, the chain behaves as a larger step random walk, but its horizontal motions of adjacent vibration cycles are related. Moreover, the character of the horizontal motion of 3 states keep consistent while the control parameters change.