School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
Phys Rev E. 2018 Mar;97(3-1):032607. doi: 10.1103/PhysRevE.97.032607.
Starting from a microscopic model, the continuum field theoretic description of the dynamics of a system of active ingredients or "particles" is presented. The equations of motion for the respective collective densities of mass and momentum follow exactly from that of a single element in the flock. The single-particle dynamics has noise and anomalous momentum dependence in its frictional terms. The equations for the collective densities are averaged over a local equilibrium distribution to obtain the corresponding coarse grained equations of fluctuating nonlinear hydrodynamics (FNH). The latter are the equations used frequently for describing active systems on the basis of intuitive arguments. The transport coefficients which appear in the macroscopic FNH equations are determined in terms of the parameters of the microscopic dynamics.
从微观模型出发，给出了活性成分或“粒子”系统动力学的连续场理论描述。相应的集体质量和动量密度的运动方程是从群体中单个元素的运动方程中精确得出的。单粒子动力学在其摩擦项中具有噪声和异常动量依赖性。集体密度的方程是通过对局部平衡分布进行平均得到的，以获得相应的粗粒涨落非线性流体动力学（FNH）的方程。后者是基于直观论点经常用于描述活性系统的方程。宏观 FNH 方程中出现的输运系数是根据微观动力学的参数确定的。
