Study on the Mechanism of Bubble Transport on Porous Structure Controlled by Surface Wettability and Microcavity

Enhancing the heat transfer performance of porous structures through effective control of wettability and surface morphology has emerged as a critical factor in ensuring efficient equipment operation under high power conditions. This paper investigates the dynamic behavior of bubble growth on porous surfaces by establishing a transient fluid continuum surface force (VOF-CSF) model, emphasizing how wettability and surface microstructure influence bubble dynamics with specific wettability and microcavity configurations. The results indicate that the adhesion effect associated with hydrophobic surfaces leads to bubbles primarily expanding in the horizontal direction, thereby facilitating their merging with adjacent bubbles. As for smooth hydrophilic porous surfaces, there exists a clear microlayer liquid film between the bubbles and particles and replenishes the liquid supply. While, the microcavity structures generate numerous vortices at the bottom of the liquid film that significantly disturb the vapor–liquid interface and significantly enhance bubble departure; additionally, the liquid film within these microcavities provides an effective rehydration pathway. Furthermore, the microclusters induced by the fluid continuously interact with the bubble boundary, significantly enhancing the growth behavior of the bubbles. This interaction results in an increase in the bubble growth rate by 30–40% and improves heat transfer performance within porous structures by 23%.