Primary Bjerknes forces

Leighton, Timothy G.; Walton, Alan J.; Pickworth, M J W

doi:10.1088/0143-0807/11/1/009

Cited by 174 publications

(113 citation statements)

References 11 publications

Supporting

Mentioning

110

Contrasting

Unclassified

Order By: Relevance

“…A feature that should be mentioned with regard to the interaction of a single bubble and a sound wave is the Bjerknes force [57]. This force can not only accelerate a bubble in a sound field to considerable speeds but also keep a bubble trapped in the node or antinode of a sound field.…”

mentioning

confidence: 99%

Bubbles with shock waves and ultrasound: a review

2015

View full text Add to dashboard Cite

The study of the interaction of bubbles with shock waves and ultrasound is sometimes termed ‘acoustic cavitation'. It is of importance in many biomedical applications where sound waves are applied. The use of shock waves and ultrasound in medical treatments is appealing because of their non-invasiveness. In this review, we present a variety of acoustics–bubble interactions, with a focus on shock wave–bubble interaction and bubble cloud phenomena. The dynamics of a single spherically oscillating bubble is rather well understood. However, when there is a nearby surface, the bubble often collapses non-spherically with a high-speed jet. The direction of the jet depends on the ‘resistance' of the boundary: the bubble jets towards a rigid boundary, splits up near an elastic boundary, and jets away from a free surface. The presence of a shock wave complicates the bubble dynamics further. We shall discuss both experimental studies using high-speed photography and numerical simulations involving shock wave–bubble interaction. In biomedical applications, instead of a single bubble, often clouds of bubbles appear (consisting of many individual bubbles). The dynamics of such a bubble cloud is even more complex. We shall show some of the phenomena observed in a high-intensity focused ultrasound (HIFU) field. The nonlinear nature of the sound field and the complex inter-bubble interaction in a cloud present challenges to a comprehensive understanding of the physics of the bubble cloud in HIFU. We conclude the article with some comments on the challenges ahead.

show abstract

mentioning

confidence: 99%

Bubbles with shock waves and ultrasound: a review

2015

View full text Add to dashboard Cite

show abstract

“…The secondary Bjerknes force occurs due to the pressure changes between two oscillating objects (Crum,259 1975, Leighton, 1994). When they oscillate in phase a negative pressure gradient between the objects is 260 formed attracting them together, however when they oscillate out of phase a positive pressure gradient is 261 formed repelling the two oscillators away from each other.…”

Section: Secondary Bjerknes Forces 258mentioning

confidence: 99%

“…This equation was derived by integrating the inertia forces over the bubble in a similar fashion to 288 calculating the surface tension by summing the local forces making it up (Leighton, 1994). Although this 289 oscillation force is not the same as the actual force acting on the ligand when the bubble oscillates, 290 calculating such force can still offer an indication of the scale of the force involved.…”

Section: Bubble Oscillation Forces 277mentioning

confidence: 99%

Effect of ultrasound on adherent microbubble contrast agents

et al. 2012

View full text Add to dashboard Cite

An investigation into the effect of clinical ultrasound exposure on adherent microbubbles is described. A flow phantom was constructed in which targeted microbubbles were attached using biotin-streptavidin linkages. Microbubbles were insonated by broadband imaging pulses (centred at 2.25 MHz) over a range of pressures (peak negative pressure (PNP) = 60-375 kPa). Individual adherent bubbles were observed optically and classified as either being isolated or with a single neighbouring bubble. It is found that bubble detachment and deflation are two significant effects, even during low amplitude ultrasound exposure. Specifically, while at very low acoustic pressure (PNP < 75 kPa) 95% of the bubbles were not affected, at medium pressure (151 kPa < P < 225 kPa) 53% of the bubbles detached and at higher pressures (301 kPa < P < 375 kPa) 96% of the bubbles detached. In addition, more than 50% of the bubbles underwent deflation at pressures between 301 and 375 kPa. At pressures between 226 and 300 kPa, more adherent bubbles detached when there was a neighbouring bubble, suggesting the role of multiple scattering and secondary Bjerknes force on bubble detachment. The flow shear, primary and secondary Bjerknes forces exerted on each bubble were calculated and compared to the estimated forces acting on the bubble due to oscillations. The oscillation force is shown to be much higher than other forces. The mechanisms of bubble detachment are discussed.

show abstract

“…According to Leighton et al [12], microbubbles excited below resonance will travel up a pressure gradient yet those above resonance will travel in the other direction. In the same publication they also indicate that this theory is valid in any field containing a pressure gradient.…”

Section: B Trapping Forcementioning

confidence: 99%