Spatial Coupling of Local Heat Sources and Mixed-Wettability Grooves Regulates Nanoscale Explosive Boiling

Localized heat generation is common in high-power energy and electronic systems, yet its spatial interaction with engineered wettability remains poorly understood. Molecular dynamics simulations were conducted to examine explosive boiling of an argon liquid film over a mixed-wettability rectangular groove under four local heat-source configurations. Only the heat-source position was varied, while the groove geometry, wettability distribution, heating area, and thermal conditions were kept unchanged. A clear decoupling between bubble nucleation and liquid-film detachment was observed. Groove-bottom heating produced the earliest nucleation at approximately 108 ps but delayed detachment to about 5.5 ns. In contrast, outer-platform heating caused the latest nucleation at approximately 187 ps but triggered detachment within about 0.8 ns. Heat-source positioning altered thermal propagation, groove depletion, bubble-growth pathways, and interfacial energy transfer. Early detachment strongly limited subsequent heat input, whereas the long-term vapor-phase atom numbers remained comparable among the four cases. These results show that heat-source location governs bubble evolution and film motion more strongly than cumulative vaporization, providing guidance for coordinating localized heat sources with mixed-wettability structures in advanced thermal-management systems.