A hydrodynamic model for the microlayer structure under heterogeneous bubbles in pool boiling

In this paper, an analytical hydrodynamic model for the microlayer under heterogeneous bubbles in pool boiling is developed accounting for the intrinsic association between the peripheral viscous boundary layer outside the microlayer and the residual flow inside the microlayer. The development of the viscous boundary layer is evaluated using the self-similarity transformation method. Then the microlayer structure is derived based on the mass and momentum conservation between the residual flow and the loss of the viscous boundary layer, characterizing as a time-dependent quadratic logarithmic function. Ulteriorly, the concept of the initial microlayer thickness is redefined by distinguishing the narrowly termed microlayer from the macrolayer. The dependence of the microlayer structure as well as the initial microlayer thickness on the bubble growth exponent is also revealed. The proposed theoretical model agrees well with available experimental data in the literatures. This model will be conducive to improving the fundamental understanding about the mechanism of microlayer formation.