The dynamics of dry active matter have implications for a diverse collection of biological phenomena spanning a range of length and time scales, such as animal flocking, cell tissue dynamics, and swarming of inserts and bacteria. Uniting these systems are a common set of symmetries and conservation laws, defining dry active fluids as a class of physical system. Many interesting behaviours have been observed at high densities, which remain difficult to simulate due to the computational demand. Here, we show how two-dimensional dry active fluids in a dense regime can be studied using a simple modification of the lattice Boltzmann method. We apply our method on a model that exhibits motility-induced phase separation, and an active model with contact inhibition of locomotion, which has relevance to collective cell migration. For the latter, we uncover multiple novel phase transitions: two first-order and one potentially critical. We further support our simulation results with an analytical treatment of the hydrodynamic equations obtained via a Chapman–Enskog coarse-graining procedure.

干活性物质的动力学对跨越一系列长度和时间尺度的各种生物现象产生影响，例如动物聚集、细胞组织动力学以及插入物和细菌的蜂拥而至。将这些系统联合起来是一组共同的对称性和守恒定律，将干燥的活性流体定义为一类物理系统。在高密度下观察到了许多有趣的行为，由于计算需求，这些行为仍然难以模拟。在这里，我们展示了如何使用格子 Boltzmann 方法的简单修改来研究稠密区域中的二维干活性流体。我们将我们的方法应用于表现出运动诱导相分离的模型，以及具有运动接触抑制的主动模型，这与集体细胞迁移有关。对于后者，我们发现了多个新的相变：两个一阶和一个潜在的关键。我们通过对通过 Chapman-Enskog 粗粒度程序获得的流体动力学方程进行分析处理，进一步支持我们的模拟结果。