Parameterization of the logarithmic layer of double-averaged streamwise velocit...

• Author(s): Franca, Mário J. ; Ferreira, Rui M. L. ; Lemmin, Ulrich
• Date: 2008
• Persistent ID: http://hdl.handle.net/10316/3950
• Origin: Estudo Geral - Universidade de Coimbra
• Subject(s): Double-averaged velocity profiles; Logarithmic law; Velocity field measurements
• Document Type: Article
• Language: English

Description

The logarithmic layer of double-averaged (in time and space) streamwise velocity profiles obtained from field measurements made in the Swiss rivers, Venoge and Chamberonne is parameterized and discussed. Velocity measurements were made using a 3D Acoustic Doppler Velocity Profiler. Both riverbeds are hydraulically rough, composed of coarse gravel, with relative submergences (h/D50) of 5.25 and 5.96, respectively. From the observations, the flow may be divided into three different layers: a roughness layer near the bed, an equivalent logarithmic layer and a surface or outer layer. It was found that a logarithmic law can describe the double-averaged profiles in the layer 0.30 < z/h < 0.75. The parameterization of the logarithmic law is discussed. Special emphasis is given to the geometric parameters roughness and zero-displacement heights and to the equivalent von Karman constant. http://www.sciencedirect.com/science/article/B6VCF-4S33NBV-1/1/bbf4c14ea5ed4a1062a36f1c5b373f12