Max Planck Institute for Mathematics in the Sciences, Inselstr. 22, D-04103 Leipzig, Germany.
Institut für Theoretische Physik, Universität Leipzig, Postfach 100 920, D-04009 Leipzig, Germany.
Phys Rev E. 2017 May;95(5-1):052142. doi: 10.1103/PhysRevE.95.052142. Epub 2017 May 25.
We derive the hydrodynamic equations of motion for a fluid of active particles described by underdamped Langevin equations that reduce to the active-Brownian-particle model, in the overdamped limit. The contraction into the hydrodynamic description is performed by locally averaging the particle dynamics with the nonequilibrium many-particle probability density, whose formal expression is found in the physically relevant limit of high friction through a multiple-time-scale analysis. This approach permits us to identify the conditions under which self-propulsion can be subsumed into the fluid stress tensor and thus to define systematically and unambiguously the local pressure of the active fluid.
我们推导出由欠阻尼朗之万方程描述的活性粒子流体的流体动力学运动方程，该方程在过阻尼极限下简化为活性布朗粒子模型。通过非平衡多粒子概率密度对粒子动力学进行局部平均，将收缩到流体描述中，其形式表达式通过多时间尺度分析在高摩擦的物理相关极限中找到。这种方法使我们能够确定自推进可以包含在流体应力张量中的条件，从而系统地、明确地定义活性流体的局部压力。
