Speaker
Description
Micro-swimmer dynamics in heterogeneous media is receiving increased interest in fluid dynamics and biological physics due to the pervasiveness of microorganisms in complex environments [1]. We present a model for a microswimmer moving in a porous medium. One such a porous medium consisting of with impurities immersed in fluid, is the Brinkman fluid which approximates a sparse matrix of stationary sphere obstacles via a linear resistance term added to the viscous fluid momentum equation. We present theoretical derivations and numerical simulations of the motion of dumb-bell micro-swimmers in Brinkman flow as well as their dynamics near no-slip and no-stress planes [2]. Next, we present continuum models, linear analysis and nonlinear simulations examining the collective dynamics and chemotactic aggregation of many such micro-swimmers in Brinkman flow, together with phase diagrams specifying parameter spaces for the predicted dynamics [3, 4]. Lastly, we discuss how such a medium affects the spread of a bacterial accumulation and compare to experiments [5]. The results provide new analytical tools for understanding locomotion in complex fluids and offer new insights on the collective behavior of active suspensions within porous or structured environments.
[1] Saverio E. Spagnolie and Patrick T. Underhill, Swimming in Complex Fluids. Annual Review of Condensed Matter Physics 14:381, 2023.
[2] Francisca Guzman-Lastra and Enkeleida Lushi, Microswimmer locomotion and hydrodynamics in Brinkman flows. Physical Review E 112(5):055110, 2025.
[3] Yasser Almoteri and Enkeleida Lushi. Microswimmer collective dynamics in Brinkman flows. Physical Review Fluids 10 (8):083102, 2025.
[4] Yasser Almoteri and Enkeleida Lushi. Chemotactic aggregation dynamics of micro-swimmers in Brinkman flows. arXiv:2504.20925, 2025.
[5] Yasser Almoteri, Bacterial motion and spread in porous environments. Ph.D. thesis, New Jersey Institute of Technology, 2023.
