Scallop dredge design using computational fluid dynamics and flume tank testing and the application of both methods to improving a low profile dredge

The Atlantic sea scallop (Placopecten magellanicus) is the focus of one of the most valuable fisheries on the east coast of the United States, but the incidental bycatch of flounder species could have negative impacts on the long-term sustainability of the scallop fishery. The low profile dredge (LPD) was conceived as a modified dredge that would reduce flounder bycatch by decreasing the vertical distance to the top of the dredge, allowing the fish to more easily swim over the top to escape. During initial development, two prototypes were tested at sea, and each reduced flounder catch with minimal reductions in scallop catch. To make continued refinement of the LPD more efficient and cost effective, we incorporated computational fluid dynamics (CFD) analysis and flume tank testing into our design strategy. The use of CFD analysis was validated with comparisons to flume tank tests and data from at-sea trials through examination of turbulent flow patterns and particle trajectories. There was a strong correspondence between the CFD simulation outputs and the results of the flume tank tests and at-sea gear trials, supporting the use of computer simulations during the early stages of gear design to speed up and reduce the cost of new gear development.