A molecular dynamics study on surface tension of microbubbles

This work is the first molecular dynamics (MD) study on the surface tension of bubbles and their related characteristics. Compared to thin films or droplets, bubbles have not been investigated using the MD simulation method for their properties owing to their inherent difficulties. To confirm their existences, a stable bubble regime with respect to simulation domain sizes is defined for the Lennard–Jones molecules. As well as the local densities, normal and tangential pressure components are calculated and used for the estimation of bubble surface tensions. While the surface tension of droplets varies as predicted by Tolmanʹs equation, that of bubbles changes slightly and is greater than the value for the planar interface by 15% or less. In addition, effects of solute molecules on the surface tension of bubbles in a binary molecule system are investigated for the cases of less and more attractive interactions between solute and solvent molecules.