Experimental Investigation of Fish Farm Hydrodynamics on 1:15 Scale Model Square Aquaculture Cages

Abstract

Hydrodynamic drag and wake properties of square aquaculture cage arrays were studied to improve understanding of nutrient dynamics from fish cages to guide the design of integrated multitrophic aquaculture (IMTA). A 1:15 scale model array (2 × 3) of square cages was developed and deployed in a large recirculating flume tank. Drag measurements were measured for individual cages within the array relative to current velocity. Results showed the highest drag for the first row of cages, with drag reducing significantly through rows 2 and 3. A wake velocity study observed velocity deficits, wake topology, wake recovery, and turbulence in the flow fields. High-velocity deficits were measured directly behind cages within the array, causing flow to be accelerated around and below the cages. The presence of a shear layer in the wake of the cages caused high levels of turbulence downstream. These results can be used to help predict patterns of nutrients released from cages into the environment and aid in the placement of nutrient extractive species in IMTA systems.