Fluorescence oil-film technique and its application in flow control

The paper describes the fluorescence oil-film technique for global skin friction measurement and its application in flow control. The theory of the fluorescence oil-film technique is introduced, and the pyramid iterative evolution method is proposed in order to accelerate convergence and improve the accuracy of solution. Two flow control experiments are carried out, including a passive control for boundary layer transition and an active control of flow over a backward-facing step (BFS). In boundary layer transition experiment, three types of the zigzag top angle (namely: 30°, 60°and 90°) are done in order to achieving optimum artificial boundary layer transition. In BFS experiment, three actuation frequency (namely: 0Hz, 35Hz and 50Hz) are done in order to comparing the control effect of different actuation frequencies The results are useful for better understanding of the flow physics and assessing the flow control strategies.