Control of boundary slip by interfacial nanobubbles: A perspective from molecular dynamics simulations

Enhancing boundary slip using interfacial nanobubbles (INBs) has gained significant interest in nanofluidic transport. In this study, we conducted a comprehensive investigation on the influence of INBs on boundary conditions for both smooth and rough substrates using molecular dynamics simulations. We analyzed the impact of INB protrusion angle, coverage percentage, quantity, and fluidity on the slip length. Our results showed that INBs always increase the slip length on a smooth substrate, with a linear increase in slip length observed with increasing surface coverage. On a rough substrate, we found that the protrusion angle, quantity, and fluidity of INBs play a crucial role in determining the slip length. Smaller protrusion angles and fewer quantities of INBs were found to be more favorable for enhancing the slip length when the INB coverage is fixed, while the correlation between boundary slip and INB quantity depended on the wetting state of the substrate when the size of the INBs was fixed with a low protrusion angle. Additionally, we revealed that the fluidity of gas molecules inside the INBs dominated the enhancement of slip length by INBs. Overall, our findings are expected to provide valuable insight into drag reduction based on INBs.