Effect of temperature and curvature on surface tension and Tolman length in the multiphase lattice Boltzmann method

Abstract

The nucleation behavior of nanobubbles and nanodroplets is highly sensitive to how the liquid-gas surface tension depends on temperature and curvature, and accurately modeling this dependence is crucial for understanding and predicting micro/nano-scale phase transition processes. We establish a dimensional transformation and use a chemical-potential multiphase lattice Boltzmann method to systematically study the effects of temperature and curvature on surface tension and Tolman length for two typical fluids: water and methane. The Tolman length is used to quantify the deviation of interfacial tension from the flat interface limit. The simulation results show that both water and methane exhibit exponential changes in surface tension with temperature at a flat interface. An equation for predicting surface tension is then derived by considering the effects of temperature and curvature. Further analysis reveals that as curvature increases, the surface tension of nanobubbles increases while the Tolman length decreases, whereas nanodroplets exhibit the opposite trends.