Gradient dynamics model for chemically driven running drops

Fuente: arXiv
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Autori principali: Niehoff, Justus, Voss, Florian, Thiele, Uwe
Natura: Preprint
Pubblicazione: 2026
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author Niehoff, Justus
Voss, Florian
Thiele, Uwe
author_facet Niehoff, Justus
Voss, Florian
Thiele, Uwe
contents We present a thermodynamically consistent model for chemically driven running drops on a solid substrate with reversible substrate adsorption of a wettability-changing chemical species. We consider drops confined to a vertical gap, thereby allowing us to first obtain a gradient dynamics description of the closed system, corresponding to a set of coupled dynamical equations for the drop profile and the chemical concentration profiles of species on the substrate and in both fluids (drop, ambient medium). Chemostatting the species in the drop and the ambient medium, we then derive a reduced model for the dynamics of the drop and the adsorbate on the substrate. When the externally imposed chemical potentials are distinct, the system is driven away from thermodynamic equilibrium, allowing for sustained drop self-propulsion across the substrate due to a wettability contrast maintained by chemical reactions. We numerically study the resulting running drops and show how they emerge from drift-pitchfork bifurcations.
format Preprint
id arxiv_https___arxiv_org_abs_2601_22962
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Gradient dynamics model for chemically driven running drops
Niehoff, Justus
Voss, Florian
Thiele, Uwe
Soft Condensed Matter
Adaptation and Self-Organizing Systems
We present a thermodynamically consistent model for chemically driven running drops on a solid substrate with reversible substrate adsorption of a wettability-changing chemical species. We consider drops confined to a vertical gap, thereby allowing us to first obtain a gradient dynamics description of the closed system, corresponding to a set of coupled dynamical equations for the drop profile and the chemical concentration profiles of species on the substrate and in both fluids (drop, ambient medium). Chemostatting the species in the drop and the ambient medium, we then derive a reduced model for the dynamics of the drop and the adsorbate on the substrate. When the externally imposed chemical potentials are distinct, the system is driven away from thermodynamic equilibrium, allowing for sustained drop self-propulsion across the substrate due to a wettability contrast maintained by chemical reactions. We numerically study the resulting running drops and show how they emerge from drift-pitchfork bifurcations.
title Gradient dynamics model for chemically driven running drops
topic Soft Condensed Matter
Adaptation and Self-Organizing Systems
url https://arxiv.org/abs/2601.22962