PROJECT SUMMARY REPORT

Project 3

Project Title	The effect of boundary turbulence on oscillating flows in the vicinity of submarine canyons
Name of Group Leader	Prof. Dr. Dieter Etling
Home Laboratory	Institut für Meteorologie und Klimatologie, Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany
E-mail address	etling@muk.uni-hannover.de
Telephone	xx49 511 762 2618

1. Project objectives (no more than 10 lines)

Laboratory experiments on oscillating flows in the vicinity of submarine canyons have been performed before in smaller rotating tanks with smooth bottom topography. In these experiments, the flow was laminar in contrast to the real ocean, where surface turbulence is always present.

The main objective of the experiments at the Coriolis turntable at Grenoble was to compare situations of oscillatory flows near canyons for laminar and turbulent flows. For this reason, experiments were performed with a smooth and rough canyon topography. The roughness was accoomplished by putting cubes on the surface of the model topography.

2. Main achievements and difficulties encountered (no more than 20 lines)

In order to provide a systematic comparison between laminar and turbulent situations, four principle setups were investigated: 1. smooth shelf topography without canyon, 2. smooth shelf with canyon, 3. rough shelf without canyon, 4. rough shelf with canyon. For each topography, two different background rotations were used and the tank was modulated with periodic oscillations. Also spin-up and spin-down experiments were performed for each setup.

Velocity fields were measured with the PIV method installed at Coriolis. Density profiles were obtained by several salinity probes.

Although the analysis of huge amount of data has still to be performed it can be said, that the presence of a canyon produced quite a strong mixing within the rough topography case, although quantitative analysis has still to be done.