EXPERIMENTAL STUDY ON THE COHERENT STRUCTURE OF THE TURBULENT BOUNDARY LAYER IN OPEN-CHANNEL FLOW

1 INTRODUCTION The coherent structure of turbulence is the most important discovery of turbulence studies in the last several decades. The coherent structure is a joint spatial state (Liang, 1999). In this space, there exist all kinds of motions that are organized and related. Namely, strip structures, large vortical structures, and other organizing flows are present. In 1932, researchers found that turbulence wasn抰 a fully random phenomenon and came to realize that the repeated emergen…

EXPERIMENTAL STUDY ON THE COHERENT STRUCTURE OF THE TURBULENT BOUNDARY LAYER IN OPEN-CHANNEL FLOW

In this paper, the new idea that using the Plane Laser Induced Fluorescence (PLIF) technique and the Acoustic Doppler Velocimeter (ADV) technique simultaneously to investigate and analyze the coherent structure of the turbulent boundary layer is developed based on previous work and simultaneously acquired image time sequences, concentration time-sequences, and velocity time sequences. Qualitative results on the bursting shape, bursting process, and vortex motion process are gained and relations on bursting height and bursting angle are established using flow visualization. Through the three kinds of time-sequences, the relation between average bursting frequency made nondimensional by interior and exterior parameters and Reynolds number for which the characteristic length is the momentum thickness is established using different data analysis methods.