The mechanism research about micro-bubble resistance reduction in the micro-scale laminar flow

Abstract

In this paper, a solid–gas–liquid phase double slip model for flat plate was established by correcting the boundary conditions with the boundary layer slip velocity. According to Karman boundary layer momentum theorem, the velocity distributions both in the solid–gas boundary layer and in the gas–liquid boundary layer were deduced. The boundary layer thickness, displacement thickness and momentum loss thickness, as well as friction coefficient were also obtained, which offer an understanding for the laminar boundary layer characteristic. The theoretical results indicate that the flow field velocity near the solid surface can be increased by the micro-bubbles on the solid surface. In the case of low Reynolds number, the boundary slip phenomenon occurs in the bubble surface boundary layer, which can lead to the resistance reduction effect. The bubble with higher height offers a longer boundary ship length, and also a more significant resistance reduction. Experimental research was also made by establishing a holographic optical experiment system and the results show that there is higher flow velocity distribution in the bubble surface boundary layer.