Surface waves on a soft viscoelastic layer produced by an oscillating microbubble
File(s)Tinguely_etal_SoftMatter2016.pdf (2.63 MB)
Accepted version
Author(s)
Tinguely, M
Hennessy, MG
Pommella, A
Matar, OK
Garbin, V
Type
Journal Article
Abstract
Ultrasound-driven bubbles can cause significant deformation of soft viscoelastic layers, for instance in surface cleaning and biomedical applications. The effect of the viscoelastic properties of a boundary on the bubble–boundary interaction has been explored only qualitatively, and remains poorly understood. We investigate the dynamic deformation of a viscoelastic layer induced by the volumetric oscillations of an ultrasound-driven microbubble. High-speed video microscopy is used to observe the deformation produced by a bubble oscillating at 17–20 kHz in contact with the surface of a hydrogel. The localised oscillating pressure applied by the bubble generates surface elastic (Rayleigh) waves on the gel, characterised by elliptical particle trajectories. The tilt angle of the elliptical trajectories varies with increasing distance from the bubble. Unexpectedly, the direction of rotation of the surface elements on the elliptical trajectories shifts from prograde to retrograde at a distance from the bubble that depends on the viscoelastic properties of the gel. To explain these behaviours, we develop a simple three-dimensional model for the deformation of a viscoelastic solid by a localised oscillating force. By using as input for the model the values of the shear modulus obtained from the propagation velocity of the Rayleigh waves, we find good qualitative agreement with the experimental observations.
Date Issued
2016-05-14
Date Acceptance
2016-04-07
Citation
Soft Matter, 2016, 12, pp.4247-4256
ISSN
1744-6848
Publisher
Royal Society of Chemistry
Start Page
4247
End Page
4256
Journal / Book Title
Soft Matter
Volume
12
Copyright Statement
© The Royal Society of Chemistry 2016
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Commission of the European Communities
Grant Number
EP/K003976/1
EP/L022176/1
639221
Subjects
Chemical Physics
03 Chemical Sciences
09 Engineering
02 Physical Sciences
Publication Status
Published
Date Publish Online
2016-04-07