Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran.
Soft Matter. 2018 Jul 4;14(26):5420-5427. doi: 10.1039/c8sm00790j.
Escape of a granular chain from a pore in a wall in the presence of diffusing granular particles on one side of the wall is studied experimentally. The escape time shows power-law behavior as a function of the chain length (τ ∝ Nα). A Langevin dynamics simulation of a polymer chain in a similar geometry is also performed and similar results to those for a granular system are obtained. A simple scaling argument and an energetic argument (based on the Onsager principle) are introduced which explain our results very well. Experiments (simulations) show that by increasing the number of particles on one side of the wall from zero, the exponent α decreases from 2.6 ± 0.1 (3.1 ± 0.1) to about 2. Both scaling and the Onsager principle argument predict α = 2 at high particle concentration, in agreement with the experiments and simulations. In the absence of particles, the scaling predicts τ = N2.5 (in agreement with the experimental result for the granular chain) and the Onsager principle predictsτ = N3 ln N, supporting the simulation result for the polymer chain. Experiments, simulations, scaling, and the Onsager principle confirm an inverse relation between τ and the density of particles on one side of the wall.
在壁一侧的扩散颗粒存在的情况下，从壁上的孔中逃离的颗粒链被实验研究。逃逸时间作为链长的函数呈现出幂律行为（τ∝Nα）。还对类似几何形状的聚合物链进行了朗之万动力学模拟，并获得了与颗粒系统相似的结果。引入了一个简单的标度论点和一个基于昂萨格原理的能量论点，它们很好地解释了我们的结果。实验（模拟）表明，通过将壁一侧的颗粒数量从零增加，指数α从 2.6±0.1（3.1±0.1）减小到约 2。标度和昂萨格原理论点都预测在高颗粒浓度下α=2，与实验和模拟结果一致。在没有颗粒的情况下，标度预测τ=N2.5（与颗粒链的实验结果一致），而昂萨格原理预测τ=N3lnN，支持聚合物链的模拟结果。实验、模拟、标度和昂萨格原理证实了τ与壁一侧的颗粒密度之间的反比关系。
