Author(s): A. Tevez; M. Mattar; H. Toniolo; R. Fernandez; F. Lopez
Linked Author(s): Carmen Elena López Fabara, Roberto Fernández
Keywords: Two-dimensional bedforms; Mean flow and turbulence structure; Coherent events
Abstract: This work presents results of an experimental project aimed at investigating the mean and turbulence structure induced by small dunes superimposed over two-dimensional bedforms, that represent field observations in a 1: 30 scale physical model of the ParanaRiver, Argentina. An acoustic Doppler velocimeter (ADV) is used to measure the three components of velocity at 25 Hz. Velocities were sampled at a total of 16verticals, with approximately 14 points in each vertical, and having a sampling length of 3 minutes each, allowing thus for an excellent spatial and temporal resolution of the flow domain. Processing of the data allowed for the computation of local vertical profiles of mean velocity, Reynolds stresses, turbulence intensities, turbulent kinetic energy, etc. as well as the estimation of spatial averages over a wavelength of the larger bedform and the computation of relative contributions of the different quadrants to the total Reynolds stress. Drag coefficients were estimated that coincide with reported values in the literature. Furthermore, the spatial structure of the turbulent coherent events (ejections and sweeps) along the dune wavelength is investigated, and the development of a roughness sublayer is characterized.
Year: 1999