MEAN FLOW AND TURBULENCE STRUCTURE OVER DUNES WITH SUPERIMPOSED SMALLER BEDFORMS

TEVEZ, ANGEL; MATTAR, MONICA; TONIOLO, HORACIO; FERNANDEZ, ROCIO LUZ; LOPEZ, FABIAN

Asutria

Conferencia; XVIII INTERNATIONAL IAHR CONFERENCE; 1999

This work presents results of an experimental project aimed to investigate the mean and turbulence structure induced by small dunes superimposed over two-dimensional bedforms, that represenr field observations in a 1:30 scale physical model of Parana River, Argentina. An acoustic Doppler anemometer is used to measure the 3 components of velocity at 25Hz, with 3 different measuring volumes specially configured for this purposes. Velocities were sampled at a total of 16 verticals, 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, Reynold 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.