Measurement of Turbulence Modification by Microbubbles Causing Frictional Drag Reduction

In this research, in order to clarify the mechanism for drag reduction caused by microbubbles, the turbulence structure of flow field including microbubbles in a horizontal channel is experimentally investigated using particle tracking velocimetry and laser induced fluorescence (PTV/LIF) technique. First, we discuss the particle image velocimetry (PIV) and PTV results for the liquid phase velocity detection. Second, using instantaneous measurement data, we obtain the profiles of the mean velocity, turbulence intensity and Reynolds stress of the liquid phase. In order to obtain the information of both the liquid and gas phases simultaneously, furthermore, we propose a new system based on the combination of PTV, LIF and infrared shadow technique (IST).