Issue 39, 2020

Vibration controlled foam yielding


In rheological terms, foams are time independent yield stress fluids, displaying properties of both solid and liquid materials. Here we measure the propagation of a 2D dry foam in a radially symmetric Hele-Shaw cell forcing local yielding. The yield rate is manipulated by mechanical vibration with frequencies from 0 to 150 Hz. The flow speed is then extracted from the video stream and analyzed using digital image correlation software. The data are modeled analytically by a Guzmanā€“Arrhenius type of energy landscape where the local yielding of foam correlates with the number of oscillations, i.e. attempts to cross the energy barrier. The model is confirmed in an auxiliary experiment where the vibrated foam stays in its flowing state at the same small driving pressures, where the flow of the unvibrated foam ceases. We conclude that the yield stress behaviour of foams under an external perturbation can be summarized using a simple energy landscape model. The vibration affects the films causing the stress to occasionally and locally exceed the yield threshold. This, thus, prevents the foam from jamming as in a static configuration even when the global driving is below the yield point of the foam.

Graphical abstract: Vibration controlled foam yielding

Supplementary files

Article information

Article type
13 Mar 2020
06 Aug 2020
First published
10 Aug 2020
This article is Open Access
Creative Commons BY license

Soft Matter, 2020,16, 9028-9034

Vibration controlled foam yielding

O. Rinkinen, L. Viitanen, J. R. Mac Intyre, J. Koivisto, A. Puisto and M. Alava, Soft Matter, 2020, 16, 9028 DOI: 10.1039/D0SM00439A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity