What causes anomalously high bubble nucleation superheats in nucleate boiling simulations by the lattice Boltzmann method?

In recent years, the pseudopotential lattice Boltzmann method (LBM) has been extensively used to study nucleate boiling heat transfer. However, a critical issue persists in existing studies: the wall superheats in nucleate boiling simulations typically reach tens to over 100 K, significantly higher than the observed range of just ∼10 K in experiments and practical engineering applications. These anomalously high superheats cast doubt on the reliability of numerical results. In this work, combining numerical simulations and theoretical analysis, we demonstrate that this discrepancy stems from the classical heterogenous nucleation mechanism assumed in existing studies, whereas bubble nucleation initiates from preexisting vapor/gas trapped in the surface crevices and defects in nucleate boiling experiments and real-world applications. Using LBM, we successfully simulate the nucleate boiling process governed by this nonclassical trapped-vapor nucleation mechanism, confirming that the required superheat for nucleate boiling can be as low as ∼10 K, consistent with observations in experiments and engineering applications.