Author(s): Stuart Cameron; Miriam Castagna; Vladimir Nikora
Linked Author(s): Stuart Cameron, Vladimir Nikora
Keywords: Open channel flow; Turbulence; Convection velocity; Velocity spectra
Abstract: Knowledge of turbulence convection velocity is important to many aspects of open-channel hydraulics including the application of Taylor’s ‘frozen’ turbulence hypothesis for converting velocity spectra between frequency and wavenumber domains, and the understanding of the multiscale structure of turbulence. While it is often convenient to approximate the eddy convection velocity as equal to the local mean velocity, studies have shown that in the near bed region z/H<0.1 (z is elevation and H is flow depth) the convection velocity may exceed the local mean velocity by over 10%. Nikora and Goring (2000) further report that convection velocity in the near-bed region may depend on the eddy size, and based on experimental data obtained in a 1 m deep irrigation canal, propose a three range model for convection velocity where: (i) at small scales (kH>30, k is wavenumber), the convection velocity is constant and approximately equal to the local mean velocity, (ii) at intermediate scales (1.4 Year: 2025