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Mixtures of self-propelled particles interacting with asymmetric obstacles

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Author(s):
Rojas-Vega, Mauricio ; de Castro, Pablo ; Soto, Rodrigo
Total Authors: 3
Document type: Journal article
Source: EUROPEAN PHYSICAL JOURNAL E; v. 46, n. 10, p. 11-pg., 2023-10-01.
Abstract

In the presence of an obstacle, active particles condensate into a surface "wetting" layer due to persistent motion. If the obstacle is asymmetric, a rectification current arises in addition to wetting. Asymmetric geometries are therefore commonly used to concentrate microorganisms like bacteria and sperms. However, most studies neglect the fact that biological active matter is diverse, composed of individuals with distinct self-propulsions. Using simulations, we study a mixture of "fast" and "slow" active Brownian disks in two dimensions interacting with large half-disk obstacles. With this prototypical obstacle geometry, we analyze how the stationary collective behavior depends on the degree of self-propulsion "diversity," defined as proportional to the difference between the self-propulsion speeds, while keeping the average self-propulsion speed fixed. A wetting layer rich in fast particles arises. The rectification current is amplified by speed diversity due to a superlinear dependence of rectification on self-propulsion speed, which arises from cooperative effects. Thus, the total rectification current cannot be obtained from an effective one-component active fluid with the same average self-propulsion speed, highlighting the importance of considering diversity in active matter. (AU)

FAPESP's process: 22/13872-5 - Pattern formation in active matter and biology: bacterial mixtures and vegetation
Grantee:Pablo Souza de Castro Melo
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 21/10139-2 - Pattern formation in active matter and biology: bacterial mixtures and vegetation
Grantee:Pablo Souza de Castro Melo
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 21/14335-0 - ICTP South American Institute for Fundamental Research: a regional center for Theoretical Physics
Grantee:Nathan Jacob Berkovits
Support Opportunities: Special Projects