Low-Pass Filtering of Active Turbulent Flows to Liquid Substrates

Fuente: arXiv
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Autori principali: Spera, Gianmarco, Yeomans, Julia M., Thampi, Sumesh P.
Natura: Preprint
Pubblicazione: 2025
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author Spera, Gianmarco
Yeomans, Julia M.
Thampi, Sumesh P.
author_facet Spera, Gianmarco
Yeomans, Julia M.
Thampi, Sumesh P.
contents To study the impact of active systems on their surroundings, we introduce a model that couples an active nematic fluid to an isotropic substrate fluid via friction. We numerically show that as the active layer develops turbulence, the substrate inherits the chaotic behaviour, exhibiting a novel form of turbulence driven by locally generated stochastic forcing from the active layer. In particular, the short-length-scale flow structures in the active layer are filtered out, so the system behaves as a de facto low-pass filter. We derive analytically the transfer function between the two layers and use it to predict the large-q decay of the substrate energy spectrum, and to investigate how tensorial quantities, such as the strain rate and the active stresses, are transmitted between the active layer and the substrate. Our analysis agrees with recent experiments measuring velocity-velocity correlations in mixtures of active and passive microtubules, and it may have implications for traction force microscopy measurements in cellular layers.
format Preprint
id arxiv_https___arxiv_org_abs_2511_22701
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Low-Pass Filtering of Active Turbulent Flows to Liquid Substrates
Spera, Gianmarco
Yeomans, Julia M.
Thampi, Sumesh P.
Soft Condensed Matter
Statistical Mechanics
To study the impact of active systems on their surroundings, we introduce a model that couples an active nematic fluid to an isotropic substrate fluid via friction. We numerically show that as the active layer develops turbulence, the substrate inherits the chaotic behaviour, exhibiting a novel form of turbulence driven by locally generated stochastic forcing from the active layer. In particular, the short-length-scale flow structures in the active layer are filtered out, so the system behaves as a de facto low-pass filter. We derive analytically the transfer function between the two layers and use it to predict the large-q decay of the substrate energy spectrum, and to investigate how tensorial quantities, such as the strain rate and the active stresses, are transmitted between the active layer and the substrate. Our analysis agrees with recent experiments measuring velocity-velocity correlations in mixtures of active and passive microtubules, and it may have implications for traction force microscopy measurements in cellular layers.
title Low-Pass Filtering of Active Turbulent Flows to Liquid Substrates
topic Soft Condensed Matter
Statistical Mechanics
url https://arxiv.org/abs/2511.22701