Enhancing the chemical reaction processes by means of the energy released in the collapse of micro bubbles or cavities in the cavitation flow is a new research area. In the previous work

a new approach of measuring concentration of free hydroxyl radicals induced in cavitation flow by using methylene blue as the indicator was developed and used to study concentration of free radical induced in Venturi cavitation flow under various experimental conditions. In the present research

the radial evolution of a cavity bubble and the corresponding collapse pressure in sonic cavitation field are obtained by solving three different bubble dynamics equations[0]: Rayleigh equation

Rayleigh-Plesset equation and Gilmore equation. By comparing with the experimental data on the radial evolution of a cavity bubble in the literature

it is found that the predicted results by the Gilmore equation

which takes account of the compressibility of fluid in addition to the viscosity and interfacial tension

agree with the experimental ones better than those by other two equations. Moreover

the theoretically predicted collapse pressures are consistent with the concentration of the free hydroxyl radical induced in the experimental venture. Thus

the concentration of the liberated free hydroxyl radical not only influences the reaction rate but also is used as an available parameter for measuring collapse intensity of cavities.