Abstract
We systematically investigate the dynamic behavior of two neighboring nanobubbles for various gas-liquid-solid interactions by molecular dynamics simulations. The weaker the interaction between gas and liquid, the larger are the bulk nanobubbles formed. The dynamic behavior of bulk nanobubbles depends not only on the ratio of gas-gas to liquid-gas interaction strengths, but also on that of solid-gas to liquid-gas interaction strengths. A very small bulk nanobubble remains stable in bulk liquid, as long as the ratio of solid-gas to liquid-gas interaction strengths is sufficiently large. Under the condition that the three-phase contact line is not pinned, different dynamic behaviors of two neighboring surface nanobubbles are observed. For a higher ratio of solid-gas to solid-liquid interaction strengths, the two neighboring surface nanobubbles can merge directly owing to the existence of a film layer of gas molecules between them. This film layer allows transfer of gas molecules from one surface nanobubble to the other along the solid substrate. This result is consistent with other theoretical results. If the interaction between solid and gas is sufficiently strong, two neighboring unsaturated surface nanobubbles can form a gas-rich layer on the solid surface. The formation of such a layer is very important for effective weakening of the solid-liquid interaction, leading to a greater reduction in drag. The effect of the ratio of solid-gas to solid-liquid interaction strengths on the shape of the gas-rich layer is also discussed in detail.
2 More- Received 5 May 2018
DOI:https://doi.org/10.1103/PhysRevFluids.3.123604
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