Collective surfing of chemically active particles

Hassan Masoud, Michael J. Shelley

Research output: Contribution to journalArticle

Abstract

We study theoretically the collective dynamics of immotile particles bound to a 2D surface atop a 3D fluid layer. These particles are chemically active and produce a chemical concentration field that creates surface-tension gradients along the surface. The resultant Marangoni stresses create flows that carry the particles, possibly concentrating them. For a 3D diffusion-dominated concentration field and Stokesian fluid we show that the surface dynamics of active particle density can be determined using nonlocal 2D surface operators. Remarkably, we also show that for both deep or shallow fluid layers this surface dynamics reduces to the 2D Keller-Segel model for the collective chemotactic aggregation of slime mold colonies. Mathematical analysis has established that the Keller-Segel model can yield finite-time, finite-mass concentration singularities. We show that such singular behavior occurs in our finite-depth system, and study the associated 3D flow structures.

Original languageEnglish (US)
Article number128304
JournalPhysical Review Letters
Volume112
Issue number12
DOIs
StatePublished - Dec 1 2013

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ASJC Scopus subject areas

  • Physics and Astronomy(all)

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