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Molecular dynamics methods are used to investigate the effect of wall wettability and initial fluid density on the nucleation and growth of nanobubbles in a nanochannel with a groove. Surface wettability is controlled by adjusting the parameters of the solid-liquid potential energy and the results show that groove wettability greatly influences the bubble nucleation process. In the case of a groove with a weak solid-liquid interaction, fluid atoms in the groove are strongly affected by repulsive forces attributed to solid atoms, the density of the fluid atoms is low, and atomic collision frequency increases. The local activation energy is concentrated in the groove, resulting in bubble nucleation. In the case of a groove with a stronger solid-liquid interaction, the bubble is formed in the center of the nanochannel. In general, the bubble radius of curvature and contact angle remain unchanged during the growth process in the case of a uniform wettability nanochannel with a groove, while significant changes are observed for a nonuniform wettability nanochannel. The radius of curvature for the generated bubble increases with increasing fluid initial density, while the steady contact angle decreases. [ABSTRACT FROM AUTHOR]

Nanostructures have significant impacts on incipient nucleation time and onset temperature during nucleate boiling. This study compares three types of surfaces, namely smooth, concave structured, and convex structured to investigate the mechanism of nucleate boiling via molecular dynamics simulations. The results show that nanostructured surfaces enhance bubble nucleation compared to smooth surfaces, provide fixed nucleation sites for initial embryo generation and shorten incipient nucleation time. Furthermore, nucleate boiling occurs more quickly on concave nanostructured surfaces than on convex ones regardless of the nanostructure size. However, with decreasing nanostructure size, the difference between them gradually decreases. A further analysis of the onset temperature is performed under various surface conditions. The onset temperature of nucleate boiling on the large concave nanostructured surface is much lower than on large convex nanostructured surface, owing to the stronger heat accumulation effect of the cavity. However, the onset temperature on the small concave nanostructured surface is higher, because liquid atoms are strongly absorbed into the small cavity and crystallized with the hydrophilic surface. The results improve the understanding of nanoscale nucleate boiling and provide a reference for the design of microelectronic devices. • Nucleate boiling of liquid argon on nanostructured surfaces is studied by MD simulation. • Nanostructured surfaces enhance bubble nucleation compared to smooth surface. • Concave nanostructures shorten incipient nucleation time compared to convex nanostructures. • Onset temperature of nucleate boiling is sensitive to the nanostructure size. [ABSTRACT FROM AUTHOR]

The authors wish to retract the referenced publication.[1] In the simulation cases of I i =0.3 and I i =0.4, the temperature control method is incorrect, resulting in flawed simulation results in Figs. 1 L. Zhang, J. Xu, and J. Lei, "Molecular dynamic simulation of bubble nucleation in a nanochannel with a groove", AIP Adv. 9, 035044 (2019).10.1063/1.5081728. [Extracted from the article]