arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 2106.02008cond-mat.softcond-mat.stat-mech
收藏

活性布朗粒子的相行为和表面张力对粒子刚度的依赖性

Dependence of phase behavior and surface tension on particle stiffness for active Brownian particles

Nicholas Lauersdorf, Thomas Kolb, Moslem Moradi, Ehssan Nazockdast, Daphne Klotsa

摘要:

我们研究准二维,单分散系统的活性布朗粒子(ABPs)的活动范围,刚度和密度。我们开发了一种微观分析方法,用于预测运动诱导相分离(MIPS)发生后形成的致密相结构,包括致密簇的面积分数,颗粒间压力和半径。我们的预测是在很好的协议与我们的布朗动力学模拟。然后,我们推导了一个连续介质模型,研究了动量方程中预测的粒子间压力、游动压力和宏观压力之间的关系。我们发现,制定逐点宏观压力作为粒子间的压力和建模的粒子活动,通过空间变化的体力-而不是体积平均游泳压力-结果在连续介质模型和微观理论的压力预测一致。该压力公式还导致相分离区域的表面张力几乎为零,而与活性、刚度和面积分数无关。此外,利用布朗动力学模拟和我们的连续介质模型,我们表明,界面宽度和表面张力,是系统的内在特性。另一方面,如果我们要排除体力活动引起的,我们发现,所得到的表面张力值是线性依赖于模拟的大小,相反的统计力学定义的表面张力。

英文摘要:

We study quasi two-dimensional, monodisperse systems of active Brownian particles (ABPs) for a range of activities, stiffnesses, and densities. We develop a microscopic, analytical method for predicting the dense phase structure formed after motility-induced phase separation (MIPS) has occurred, including the dense cluster's area fraction, interparticle pressure, and radius. Our predictions are in good agreement with our Brownian dynamics simulations. We, then, derive a continuum model to investigate the relationship between the predicted interparticle pressure, the swim pressure, and the macroscopic pressure in the momentum equation. We find that formulating the point-wise macroscopic pressure as the interparticle pressure and modeling the particle activity through a spatially variant body force -- as opposed to a volume-averaged swim pressure -- results in consistent predictions of pressure in both the continuum model and the microscopic theory. This formulation of pressure also results in nearly zero surface tension for the phase separated domains, irrespective of activity, stiffness, and area fraction. Furthermore, using Brownian dynamics simulations and our continuum model, we showed that both the interface width and surface tension, are intrinsic characteristics of the system. On the other hand, if we were to exclude the body force induced by activity, we find that the resulting surface tension values are linearly dependent on the size of the simulation, in contrast to the statistical mechanical definition of surface tension.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑