布朗粒子在狹窄通道中的傳輸行為－通道幾何形狀的影響

Abstract

在非平衡態中，布朗粒子在有不對稱性與不均向性的通道中運動時，粒子的運動會出現往固定方向漂移的現象。我們以通道的寬度變化形成的腔室形狀不對稱來造成不對稱性，而不均向性則由通道底部溝槽產生。我們製作了風箏型與三角形腔室形狀的通道來比較型狀對漂移運動的影響。我們發現三角形相對於風箏型的通道反而使其中的粒子傳輸速度變慢。並且也較大程度的限制了粒子的隨機擴散，使擴散係數也較低。透過分析兩通道中粒子的瞬時速度分佈，我們發現能量在三角形通道中較難傳導到縱向的運動中。使得粒子的漂移與擴散都在三角形通道中都較慢。

In non-equilibrium system, the drift motion happens as a Brownian particle moving in the channel with asymmetry and anisotropy. The asymmetry was given by asymmetrical shape of cells form the channel. Anisotropy was given by grooves built along the channel. We made two channels with different cell shapes, kiteshape and triangle, to compare the effect on drift motion caused by geometry of channel. We found particle in triangular channel had slower drift and diffusion than particle in kite shape channel with the same energy input. By analysing the instantaneous velocity distribution, We found that it was more difficult to transfer energy from transverse direction to longitudinal direction for particle in triangular channel. With less energy, particle drifted slower in triangular channel than particle in kite shape channel.