Droplet spreading in a wedge: A route to fluid rheology for power-law liquids

Fuente: arXiv
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Autori principali: Moura, Marcel, Kern, Vanessa, Måløy, Knut Jørgen, Carlson, Andreas, Flekkøy, Eirik G.
Natura: Preprint
Pubblicazione: 2025
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author Moura, Marcel
Kern, Vanessa
Måløy, Knut Jørgen
Carlson, Andreas
Flekkøy, Eirik G.
author_facet Moura, Marcel
Kern, Vanessa
Måløy, Knut Jørgen
Carlson, Andreas
Flekkøy, Eirik G.
contents Measuring the rheology of liquids typically requires precise control over shear rates and stresses. Here, we describe an alternative route for predicting the characteristic features of a power-law fluid by simply observing the capillary spreading dynamics of viscous droplets in a wedge-shaped geometry. In this confined setting, capillary and viscous forces interact to produce a spreading dynamics described by anomalous diffusion, a process where the front position grows as a power-law in time with an exponent that differs from the value $1/2$ found in classical diffusion. We derive a nonlinear diffusion equation that captures this behavior, and we show that the diffusion exponent is directly related to the rheological exponent of the fluid. We verify this relationship by using both experiments and simulations for different power-law fluids. As the predictions are independent from flow-specific details, this approach provides a robust tool for inferring rheological properties from the spreading dynamics.
format Preprint
id arxiv_https___arxiv_org_abs_2501_14571
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Droplet spreading in a wedge: A route to fluid rheology for power-law liquids
Moura, Marcel
Kern, Vanessa
Måløy, Knut Jørgen
Carlson, Andreas
Flekkøy, Eirik G.
Fluid Dynamics
Measuring the rheology of liquids typically requires precise control over shear rates and stresses. Here, we describe an alternative route for predicting the characteristic features of a power-law fluid by simply observing the capillary spreading dynamics of viscous droplets in a wedge-shaped geometry. In this confined setting, capillary and viscous forces interact to produce a spreading dynamics described by anomalous diffusion, a process where the front position grows as a power-law in time with an exponent that differs from the value $1/2$ found in classical diffusion. We derive a nonlinear diffusion equation that captures this behavior, and we show that the diffusion exponent is directly related to the rheological exponent of the fluid. We verify this relationship by using both experiments and simulations for different power-law fluids. As the predictions are independent from flow-specific details, this approach provides a robust tool for inferring rheological properties from the spreading dynamics.
title Droplet spreading in a wedge: A route to fluid rheology for power-law liquids
topic Fluid Dynamics
url https://arxiv.org/abs/2501.14571