DOI: 10.5176/2301-394X_ACE15.125
Authors: Kimchhun Kang and Jae Hyeon Park
Abstract:
Evaluation of the bed shear stress in open-channel flow is very important in estimating drag forces of channel designing, and analyzing scour in channel. However, it is hard to estimate the bed shear stress precisely, essentially in high range velocity. This experimental study has compared bed shear stress approximation by indirect methods (Reynolds Stress, Turbulent Kinetic Energy (TKE), and Reach-averaged bed shear stress) which generates data from acoustic Doppler velocimeter (ADV) and direct method (Shear Stress Measurement Device) in a smooth rectangular channel which velocity up to 1.60 m/s. The experiment results show that, for velocity range from 0 to 1.0 m/s, the Reynolds Stress estimate is closest to the Reach-averaged method (within 13.5{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} of difference). These two methods are the appropriate methods for bed shear stress estimate. But the weak point of Reach-averaged method is not appropriate for complex flow field, local, small-scale estimates of the variation in shear stress. TKE method seems overestimate bed shear stress. For velocity range from 1.0 to 1.60 m/s, Measurement Device shows very good fulfillment to measure the bed shear stress. The TKE method estimate is closest to the Measurement Device (within 1.9{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} of difference). TKE is an appropriate method for estimate of bed shear stress. Reach averaged method represents only average value of bed shear stress but Reynolds Stress seems underestimate bed shear stress.
Keywords: Bed shear stress; shear stress measurement device; Reynolds stress; turbulent kinetic energy; Reach-averaged bed shear stress; ADV
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