High-resolution computational fluid dynamics modelling of suspended shellfish structures

Aquaculture structures are responsible for flow disturbances that extend over a large range of scales. In the case of shellfish aquaculture, those scales extend from the size of an individual shellfish to the size of a whole farm with intermediate scales being the size of a shellfish structure or of a block of shellfish structures. The influence of block spacing and angle is investigated by the mean of a 2D high resolution computational fluid dynamics model. Block angle is found to be the main relevant parameter controlling to a large extent the mixing generated by the shellfish structures. Strong sensitivity is found for small angles. Nevertheless, it is shown that for a limited number of blocks, upstream turbulence still dominates the degree of the total mixing within the farm, and that total flow reduction is little affected by the orientation of the blocks. A simple analytical model is presented that predicts most of the numerical results.