Abstract
To measure local instantaneous velocity and velocity gradients, a molecular tagging velocimetry based on photobleaching reaction was developed in this study. The photobleaching is an irreversible photodegradation of a fluorescent dye, and therefore the velocity and its gradient can be measured from the translation and deformation of photobleached tag, respectively. The method was applied to a laminar pipe flow, laminar suction flow, and a turbulent flow in a square duct. It was confirmed that the method can accurately measure radial distributions of liquid velocity and shear stress in the pipe flow and that the method is applicable to turbulent flows.
