Visualization of behavior of single bubble in horizontal turbulent channel flow

Abstract

A variety of hypotheses have been prpposed to explain primary mechanism of frictonal drag reduction by bubbles which are injected into turbulent boundar layers. One of the way to clarify the fundamentals, experiment on single bubble behavior can offer the hints associated with two-phase flow dynamcis. We conducted a Lagrangian tracking of single bubbles in a horizontal turbulent channel flow varing the bulk Reynolds number from 5,000 to 20,000. As the results, the bubble suspended layer from the wall, which takes significantly differnet positions, is discussed with considering bubble deformability, bubble buoyancy as well as lowal wall shear stress around the bubbles.