Vibration controlled foam yielding
Oona Rinkinen1, Leevi Viitanen1, Jonatan R Mac Intyre1
1Aalto University, School of Science, Department of Applied Physics, P.O. Box 11100, 00076 Aalto, Finland. leevi.viitanen@aalto.fi jonatan.macintyre@aalto.fi juha.koivisto@aalto.fi antti.puisto@aalto.fi mikko.alava@aalto.fi.
Soft Matter
|August 26, 2020
Summary
Mechanical vibration prevents foams from jamming by overcoming yield stress. This study models foam yielding using an energy landscape, showing vibration aids flow even at low pressures.
Area of Science:
- Rheology and soft matter physics.
- Foam dynamics and complex fluid behavior.
Background:
- Foams exhibit time-independent yield stress, acting as both solid and liquid.
- Understanding foam flow is crucial for applications in food, cosmetics, and materials science.
Purpose of the Study:
- To investigate the effect of mechanical vibration on the yielding and flow of 2D dry foams.
- To develop and validate an analytical model for foam rheology under external perturbation.
Main Methods:
- Utilizing a Hele-Shaw cell to confine and observe 2D dry foam propagation.
- Applying controlled mechanical vibrations (0-150 Hz) to manipulate local yielding.
- Analyzing flow dynamics using digital image correlation software.
Main Results:
- Foam flow speed directly correlates with vibration frequency and attempts to overcome energy barriers.
- Vibrated foams maintain flow at low driving pressures where unvibrated foams cease.
- A Guzman-Arrhenius energy landscape model accurately describes foam yielding behavior.
Conclusions:
- Foam yield stress behavior under vibration can be explained by a simple energy landscape model.
- Vibration locally exceeds yield thresholds, preventing static jamming even below the bulk yield point.
- External perturbations offer a method to control and sustain foam flow.
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