Experimental study of the near-field impact of an oyster table on the flow
Résumé
Oyster farming structures are artificial obstacles which disturb tidal flow and wave propagation. These effects can induce modifications of erosion and sedimentation patterns, turbidity changes, local silting up and can be threatening for the shellfish farming itself. The understanding of the impact of these structures in terms of hydrodynamics and sediment dynamics in the far-field, i.e. at the scale of a bay, is a very challenging task. In order to investigate the far-field impact, it is very important to understand in the first place all the changes which occur at a smaller scale, i.e. at the scale of a single table for a farm consisting of oyster tables made of metallic wire structures on which porous bags of oysters are laid. This work is carried out through the idealized representation of the in-situ flow in a free surface flume tank. The flow characteristics around the overall structure are determined from velocity measurements obtained by laser velocimetry. The results highlight an asymmetric development of the boundary layers which suggest the existence of preferential areas for silting up and suspended matter fragmentation under the table.