| Popis: |
In the present study large scale coherent structures in compound open-channel flows are investigated experimentally using Digital Particle Image Velocimetry (DPIV). In a straight flume images of particles are recorded in a horizontal plane using a CCD-camera and evaluated to reveal instantaneous velocity fields. Afterwards, data is validated using an advanced dynamic filter algorithm. To obtain fluctuating velocity fields different decomposition techniques are applied and compared with respect to their capability to detect turbulent structures. The mean-bulk Galilean decomposition proves best and is used for further analysis. Instantaneous fluctuating velocity fields are examined regarding occurrence of vortical structures and their spatial extension, direction of rotation, movement and interaction with other vortices. |
