Figure 6.

Calculations to benchmark model performance for vapor bubbles, whereby bubble motion is coupled to thermal conduction in the surrounding liquid. (a) The radial growth of superheated vapor bubbles is plotted for the surrounding liquid at two initial temperatures. PZ and SCL model calculations are compared with the asymptotic approximation derived by Plesset and Zwick.52 Note that the initial bubble growth rate is influenced primarily by the initial radius (assumed to be 20 μm here) rather than thermal conduction in the liquid; accordingly, this rate is not a part of the asymptotic approximation. With regard to the ultimate growth rates, the PZ model predicts slightly faster growth while the SCL model predicts much faster growth. Identical fluid properties are used for calculations from the present models and the asymptotic approximation. (b) Calculations of rectified heat transfer are plotted for a 35 μm bubble in 100 °C water after excitation by a 0.4 atm sine wave at 1 kHz. Note that the plotted bubble radius is normalized relative to the resonance size of 2.71 mm for a vapor bubble. The plot includes lines for the PZ and SCL models as well as an envelope that represents the results reported in Fig. 3 from Hao and Prosperetti (H&P).53