Dual grid level set method based direct numerical simulations of nucleate boiling with oscillating base plate

Abstract

Abstract We have used Direct Numerical Simulations to study the effect of base plate oscillations on nucleate boiling heat transfer at low super heat in the isolated bubble regime. A sharp interface dual grid level set method (SI-DGLSM) has been used to carry out the numerical simulations. Here, dual grid implies that the grid points for the discretized temperature and level set functions are twice as refined as that for the discretized velocity and pressure fields. A semi-implicit projection method is used to solve the mass, momentum and energy conservation equations. For nucleate boiling on oscillating plate with oscillations perpendicular to plate surface, a lock-on regime has been observed, during which the frequency of bubble departure synchronizes with the frequency of plate oscillation over a range of oscillation amplitude and frequencies. The size of the bubbles have been shown to be effectively controlled by the frequency of plate oscillation within this lock-on regime. The lock-on of bubble departure and plate oscillations is especially robust when the amplitude of plate oscillations is increased. The increase in oscillation amplitude also helps in increasing the average Nusselt number by around 22%. We use data from our simulations to show that the enhancement in Nusselt number can mainly be attributed to larger downflow in the liquid, and therefore thinner thermal boundary layer, due to plate oscillation.