- #1

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_{g}and vapour P

_{v}in the bubble must equal the crushing forces i.e. the hydrostatic forces P

_{h}and those due to surface tension 2sigma/R

_{0}. So we have

##P_{v}+P_{g}=P_{h}+ \frac{2\sigma }{R_{0}}##

Now we apply ultrasound so the pressure in the liquid is now Ph + Pa where:

##P_{a}=P_{A} sin 2\pi ft##

BUT the ultrasound causes cavitation of the bubble! And when the bubble is largest we have:

##P_{V}>(P_{h}-P_{a}) + \frac{2\sigma }{R_{0}} - P_{g}##

Now my question, he writes the next equation as:

##P_{V}-\frac{2\sigma }{R_{0}}=P_{V}^{'}>(P_{h}-P_{a})##

BUT he doesnt define ##P_{V}^{'}## so I'm a little lost.

Could someone tell me what a dash would generally mean?

It's from p.61 of this paper:

http://gendocs.ru/docs/37/36518/conv_1/file1.pdf

Thanks in advance for any help!