Numerical simulation of single bubble evolution in low gravity with fluctuation

Abstract

The nucleate boiling under low gravity was solved numerically, with the thermocapillary force considered in the momentum equations. The two-phase interface was captured with the phase field method, and the superheated layer was included in the model. The effects of thermocapillary convection and g-jitter (fluctuating gravity) on the bubble dynamics and heat transfer were explored. It was found that the thermocapillary convection shortened the growth period of the bubble by about 0.26 s in the low gravity (low-g). The affected area of the temperature and flow fields was wider with consideration of thermocapillary convection, and the heat transfer was enhanced consequently. Moreover, the bubble dynamics showed different characteristics in the conditions with and without the g-jitter. The velocity of the contact line fluctuated between positive and negative values in g-jitter. As the amplitude of the g-jitter increased from 0 to 0.04, the departure time and departure radius decreased by 31.2% and 14.1%, respectively. Nevertheless, the average heat flux increased with the increase of the g-jitter amplitude. The frequency of g-jitter showed a negative correlation with departure time and departure radius of the bubble, whereas average heat flux showed a positive correlation with the frequency of g-jitter.