2024/08/19 by Prajapati, Soni D., Bhatnagar, Akshay, Gupta, Anupam · 1 citation
#FOS: Physical sciences #Soft Condensed Matter (cond-mat.soft)
paper · doi:10.48550/arxiv.2408.09763
We simulate active Brownian particles (ABPs) with soft-repulsive interactions subjected to a four-roll-mill flow. In the absence of flow, this system exhibits motility-induced phase separation (MIPS). To investigate the interplay between MIPS and flow-induced mixing, we introduce dimensionless parameters: a scaled time, τ, and a scaled velocity, \rm v, characterizing the ratio of ABP to fluid time and velocity scales, respectively. The parameter space defined by τ and \rm v reveals three distinct ABP distribution regimes. At low velocities \rm v ≪ 1, flow dominates, leading to a homogeneous mixture. Conversely, at high velocities \rm v ≫ 1, motility prevails, resulting in MIPS. In the intermediate regime (\rm v ∼ 1), the system's behavior depends on τ. For τ<1, a moderately mixed homogeneous phase emerges, while for τ>1, a novel phase, termed flow-induced phase separation (FIPS), arises due to the combined effects of flow topology and ABP motility and size. To characterize these phases, we analyze drift velocity, diffusivity, mean-squared displacement, giant number fluctuations, radial distribution function, and cluster-size distribution.