DOI: 10.1615/ICHMT.2009.TurbulHeatMassTransf
ISBN Print: 978-1-56700-262-1
ISSN: 2377-2816
Turbulence and drag associated with water boundary layer flow over wavy plates at a high Reynolds number
ABSTRACT
We have measured velocities in turbulent boundary-layer flow along several types of wavy plates located on the bottom of a shallow open channel at a high Reynolds number. Also, we have measured total drag acting on these plates by the flow. The friction drag is estimated from the gradient of mean velocity near the plate surface. The pressure drag is evaluated from the difference between the total drag and the friction drag. The results show that the Reynolds-shear stress in the case of a gentle-uphill, steep-downhill wavy plate of a/λ=0.035 (a is the amplitude and λ is the wavelength of the wavy surface) is lower than that in the cases of the sinusoidal wavy and steep-uphill plates. The friction drags of the wavy plates were slightly lower than that of the flat plate. These facts are due to the small-scale recirculation flow appearing intermittently.