Key Findings:

– A novel dynamical theory of boiling based on Fluctuating hydrodynamics and the Diffuse Interface approach has been developed. The proposed Fluctuating Diffuse Interface (FDI) approach can describe boiling from stochastic nucleation up to macroscopic bubble dynamics.

– The role of wettability in the macroscopic observables of boiling was elucidated. Hydrophobic surfaces showed faster vapour production kinetics compared to hydrophilic surfaces.

– Sparse nanometric hydrophobic spots on an otherwise hydrophilic surface were found sufficient to trigger nucleation at lower superheat, significantly reducing the boiling onset temperature, in line with experimental observations in the litterature.

– A Tolman length corrected classical nucleation theory was able to estimate the nucleation temperature observed in the simulations.

Significance: The proposed mesoscale approach constitutes the missing link between macroscopic approaches (i.e. Volume of Fluid, Level Set) and molecular dynamics simulations. It enables unprecedented computational efficiency to address the poorly explored nano-to-micro range of scales in boiling. Therefore, in case that a VOF-based approach, that so far is usually applied succesfully at domains and scales in the range of hundreds of micrometers up to tens of millimiters, can be proven to predict accuratelly also at lower spatial and temporal scales, the indirect or also the direct coupling of the FDI meso-scale approach with the enhanced VOF method becomes viable. For thos purpose the next milestone that was achieved was to explore and justify for the first time that our enhanced VOF-based numerical simulation framework can indeed predict accuratelly the bubble dynamics and growth characteristics at sub-micron scales.