The Physical Effects of Bubbles and Cavitation in High Intensity ...

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A Primer on Bubble Acoustics Nonlinear Response of a single bubble Consider force balance across a bubble wall Internal: gas pressure vapor pressure External: hydrostatic pressure, surface tension Dynamics: acoustic stress, viscous stress Rayleigh Plesset Equation 1-D radial motion, Newtonian incompressible fluid # " o % R˙ R ˙ + 3 $ 2 ˙ R 2 & ,# ( = % P ' o ) P v + 2* &# . % - $ ' $ R o ( R o R 3+ & ( ' / + P v 0 1 ) 2* R ) 4µ R ˙ R ) ( P o + P a sin2t) Inertial Terms Total Internal Pressure Total External Pressure Keller Miksis Equation Accounts for the compressibility of the liquid 6
Acoustic Cavitation A Recipe… Start with a preferential site for liquid rupture Physical impurity, preexisting gas cavity Apply an acoustic stress strong enough to overcome… Surface tension, inertia, viscous drag Bubble responds in accordance with nonlinear equation of motion Two Classes of Bubble Response… 7
Page 1 and 2: The Physical Effects of Bubbles and
Page 3 and 4: Medical Ultrasonics in a Nutshell
Page 5: A Prominent Role for Microbubbles!
Page 9 and 10: Physical Effects Stable Cavitation
Page 11 and 12: Physical Effects Inertial Cavitatio
Page 13 and 14: Physical Effects Inertial Cavitatio
Page 15 and 16: Physical Effects Collapse Jets Extr
Page 17 and 18: Geneology of Cavitation Cloud Colla
Page 19 and 20: Focused Ultrasound Surgery Tissue H
Page 21 and 22: Focused Ultrasound Surgery Tissue H
Page 23 and 24: Focused Ultrasound Surgery Dependen
Page 25 and 26: Sensing Accelerated Heating with No
Page 27 and 28: Can We Control -- or at least monit
Page 29 and 30: A Simple Cavitation Controller? 10
Page 31 and 32: What Happens if the Tissue Gets Too
Page 33 and 34: Not Necessarily So long as you
Page 35: I Thank… YOU, FOR YOUR KIND ATTEN

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