(378e) Numerical Simulation of Bubble Growth and Collapse in a Pool of Liquid

Bubble dynamics (bubble growth, departure and collapse) in pool boiling has been studied numerically in the recent past without the consideration of the effect of phase motions¹. The phase motion essentially affects the spatial variation of temperature of liquid surrounding the vapour bubble, the temperature gradient at interface, and heat and mass transfer through the interface. The present work attempts to numerically solve the energy equation of the surrounding liquid for spatio-temporal variation of temperature in a spherical geometry², which includes the phase motions. The motion of bubble is considered to attain rise velocity, assuming a bubble of a finite size initially placed in the pool of liquid, which is allowed to grow and collapse. The radial velocity component is obtained from the streamlines of the surrounding liquid using the method² with an additional term due to the velocity of bubble wall; the approach velocity is approximated to the rise velocity. The energy equation at interface computes the rate of bubble growth and collapse, and the Rayleigh-Plesset equation the vapour pressure inside the bubble. The work also demonstrates a considerable improvement by the present method over the semi-analytical method¹ while validating with the experimental and theoretical works that include the phase motion. A large number of grid points is required for the numerical solution with acceptable accuracy. To improve the computational efficiency, the number of grid points plays a vital role depending on the degree of superheat and subcooling, and the bubble radius varying with time.

Keywords: Bubble dynamics, bubble motion, bubble growth, bubble collapse, pool boiling

References

1. Bhati J. Numerical simulation of bubble dynamics in boiling. PhD Thesis, submitted to National Institute of Technology Durgapur, 2019.
2. Bird RB, Stewart WE, Lightfoot EN. Transport phenomena, John Wiley & Sons, New York, 1960.