This thesis deals with the experimental analysis of the flow structure in the scour of a cylindrical bridge pier. It aims at identifying the influences of the flow quantities on the development of the scour. For this purpose, the Stereo Particle Image Velocimetry (Stereo PIV) is applied, in order to collect information about the three components of the flow velocities without disturbing the flow. The meas- urements are conducted in the symmetry plane in front of a cylinder and in a plane of 45-degree rotation to the flow direction at the Reynolds number 20.000 and 39.000. One measurement consists of about 40.000 image pairs. Because of the high computational effort, only 10.000 raw data at the Reynolds number 20.000 are evaluated. Thus, the time averaged values of the flow velocities, the components of the Reynolds stress tensor, the rotation and the turbulent kinetic energy are deter- mined. The results include sufficient valid data and a low relative error of the mean value that makes it qualified for comparison with other experiments. To the knowledge of the author there do not exist any experiments with a comparable spatial resolution in the scour. Therefore, the results are com- pared to the ones at flat plane in front of a cylinder measured with Standard Particle Image Veloci- metry. It becomes clear that the flow structure in the scour is very similar to the one at the flat plane. Additionally, the information about the processes perpendicular to the plane are now available, due to the Stereo PIV. The results state that, the horseshoe vortex moves back and forth along the scour and the center is shifted upstream, compared to the flat plane. The turbulent kinetic energy reaches the same structure and magnitude as at the flat plane. The results from the second experiment in the 45-degree plane point out that the considered parameters decrease with increasing distance to the symmetry plane and the horseshoe vortex loses his dynamic and strength. It should be mentioned that the spatial resolution near the wall is very low, due to the high reflection at the scour and the oblique angle of measurement. At the time being there is no alternative measuring technique, which reaches to a higher resolution in the near wall region [12] . Overall the results of this work contribute to a better understanding of the processes in a scour and form the basis for further investigations.     «

This thesis deals with the experimental analysis of the flow structure in the scour of a cylindrical bridge pier. It aims at identifying the influences of the flow quantities on the development of the scour. For this purpose, the Stereo Particle Image Velocimetry (Stereo PIV) is applied, in order to collect information about the three components of the flow velocities without disturbing the flow. The meas- urements are conducted in the symmetry plane in front of a cylinder and in a plane of 45-d...     »