English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Yield-stress fluids naturally trap small bubbles when their buoyancy appliesan insufficient stress to induce local yielding of the material. Under acousticexcitation, trapped bubbles can be driven into volumetric oscillations andapply an additional local strain and stress that can trigger yielding andassist their release. In this paper we explore different regimes of microbubbleoscillation and translation driven by an ultrasound field in a modelyield-stress fluid, a Carbopol microgel. We first analyse the linear bubbleoscillation dynamics to measure the local, high-frequency viscosity of thematerial. We then use acoustic pressure gradients to induce bubble translationand examine the elastic part of the response of the material below yielding. Wefind that, at moderate pressure amplitude, the additional stresses applied byvolumetric oscillations and acoustic radiation forces do not lead to anydetectable irreversible bubble motion. At high pressure amplitude, we observenon-spherical shape oscillations that result in erratic bubble motion. Theshape modes and critical pressures we observe differ from the predictions of arecent model of shape oscillations in soft solids.Based on our findings, wediscuss possible reasons for the lack of bubble release in Carbopol and suggestother systems in which ultrasound-assisted bubble rise may be observed.

Acoustic Bubble Dynamics in a Yield-Stress Fluids