Dynamic viscosity of water containing large-sized nanobubbles simulated with coarse-grained molecular dynamics model

Nanobubbles have received widespread interest due to prospective applications in various disciplines. A crucial approach to investigating nanobubbles is molecular dynamics simulation. However, investigating large-sized bulk nanobubbles requires expensive computer resources. By coarsening the water molecules, the computational complexity can be significantly reduced, making the investigation of large-sized nanobubbles possible. This article presents simulations and analysis of the microscopic characteristics of water containing large-sized nanobubbles using coarse-grained molecular dynamics, especially, the Green-Kubo formula is used to calculate the dynamic viscosity. We first observe the effects of temperature, pressure and diameter on the viscosity of nanobubble water. The results indicate that higher temperature leads to lower viscosity of nanobubble water while higher pressure leads to higher viscosity of nanobubble water. Additionally, it is observed that the viscosity of nanobubble water decreases gradually as the diameter of the nanobubble increases. It is a remarkable fact that the viscosity of nanobubble water is lower than that of water at the same temperature and pressure, which means the viscosity of water can be reduced with the addition of nanobubble. At last, a viscosity correction model for nanobubble water at room temperature is successfully developed.