How the distribution and morphology of interfacial gas bubbles enhancing the boundary slip of fluid flow

Abstract

A comprehensive investigation on how distribution and morphology of interfacial gas bubbles (IGBs) affecting the boundary slip of fluid flow was conducted by using finite element simulation. Results showed that the IGB dispersion, protrusion angle, coverage area, lateral size, height and quantity play crucial roles in determining the slip length. The slip length shows an decrease with the increase of dispersion index. Especially for IGB spacing distance smaller than 0.1 times IGB lateral size, the slip length shows an obvious increase. Moreover, a larger IGB lateral size and fewer IGB quantity are more effective for drag reduction (protrusion angle θ smaller than critical angle θc) or for drag increase (θ > θc) when IGB coverage area and protrusion angle are fixed.