RELIABILITY OF 5-BEAM LDV FIBEROPTIC PROBE FOR TURBULENCE MEASUREMENTS IN THE WALL REGION OF OPEN-CHANNEL FLOW

摘要

A 5-beam LDV fiberoptic probe is used for an experimental investigation of turbulent open (water) channel flow at ReτH = 601 (the Reynolds number based on friction velocity and hydraulic radius). The performances of the instrument are mainly investigated in the region near the bottom wall of the open channel, with regard to both mean and fluctuating velocity components, and the results are compared with the data of numerical nature related to DNS calculations, as performed in the case of the plane channel (the flow between two parallel plates) at a very close value of the Reynolds number. Due to the different flow conditions along the vertical direction in the experimental open channel and in the numerical plane channel, near-wall comparisons are considered only for the streamwise- and spanwise-velocity components.