Statistics and morphologies of stable droplets in scalar active fluids

Fuente: arXiv
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Auteurs principaux: Hertäg, Kathrin, Robinson, Joshua F., Speck, Thomas
Format: Preprint
Publié: 2025
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author Hertäg, Kathrin
Robinson, Joshua F.
Speck, Thomas
author_facet Hertäg, Kathrin
Robinson, Joshua F.
Speck, Thomas
contents Conventional phase segregation is controlled by a positive interfacial tension, which implies that the system relaxes towards a state in which the interfacial area (or length) is minimized, typically manifesting as a single droplet that grows with the system size. Intriguingly, the extension of the underlying Model B paradigm by two non-potential terms (Active Model B+) is able to describe the stable coexistence of many finite droplets. Here we numerical study Active Model B+ in the vicinity of the transition between a single droplet (macrophase segregation) and multiple droplets (microphase segregation). Our results show that, although noise shifts transitions, the overall agreement with the mean-field theoretical predictions is very good. We find a strong correlation of droplet properties with a single parameter that determines the number, density, and the fractal dimension of droplets. Deeper inside the droplet phase we observe another transition to a hexagonal lattice of regular droplets.
format Preprint
id arxiv_https___arxiv_org_abs_2509_19154
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Statistics and morphologies of stable droplets in scalar active fluids
Hertäg, Kathrin
Robinson, Joshua F.
Speck, Thomas
Soft Condensed Matter
Conventional phase segregation is controlled by a positive interfacial tension, which implies that the system relaxes towards a state in which the interfacial area (or length) is minimized, typically manifesting as a single droplet that grows with the system size. Intriguingly, the extension of the underlying Model B paradigm by two non-potential terms (Active Model B+) is able to describe the stable coexistence of many finite droplets. Here we numerical study Active Model B+ in the vicinity of the transition between a single droplet (macrophase segregation) and multiple droplets (microphase segregation). Our results show that, although noise shifts transitions, the overall agreement with the mean-field theoretical predictions is very good. We find a strong correlation of droplet properties with a single parameter that determines the number, density, and the fractal dimension of droplets. Deeper inside the droplet phase we observe another transition to a hexagonal lattice of regular droplets.
title Statistics and morphologies of stable droplets in scalar active fluids
topic Soft Condensed Matter
url https://arxiv.org/abs/2509.19154