3-DIMENSIONAL FLOW FIELD VISUALIZATION IN THE WAKE OF A GROUP OF FISH FARMING SEA CAGES

There is a need for better understanding of the flow dynamics through and around ocean fish farms. There has been documented discrepancy, between experimental measurements and Computational Fluid Dynamics (CFD), of the velocity deficit in the wake of a fish farming cage [1]. A visualization of the actual flow field is a strong tool in understanding the dynamics of the flow going through and around a group of fish farming sea cages of the gravity type. An experiment with the aim of visualizing the 3-dimensional (3-D) flow field in the wake of a fish farm was conducted at a fish farm located in the bay of Tórshavn, Faroe Islands.

The current measurements where performed with a boat mounted a RD Instruments (RDI) Workhorse Sentinel 300 KHz Acoustic Doppler Current Profiler (ADCP) with Bottom Track (BT) software installed. Measurement transect where performed in the water domain in the wake of the fish sea cages. Bottom mounted ADCP are deployed at key positions around the fish farm site in order to capture the free stream velocity of the current flow. Measured current velocities are normalized by means of the free stream current velocity. Appropriate filters are applied to the velocity data to filter away noise from boat motion during measurement. Processed velocity data is interpolated to a 3-D volume containing the bathymetry data of the area.