Optimal marine farm structures.
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
This thesis documents a new modelling approach for assessing the interplay between marine mussels and their environment, and presents the development of multi-scale methodology for addressing the question of optimal aquaculture structures. The Lattice Boltzmann (LB) method can accommodate the complex geometry of mussel clusters. This hydrodynamic model is expanded to incorporate physiological activity, in order to quantify the relationship between mussels, the surrounding flow and the spatial distribution of phytoplankton concentration (the mussel food supply). Uptake results, from simulations at the smallest scale of modelling, quantify the non-linear effect of competition for phytoplankton and are shown to be generally independent of diffusive conditions. Statistics of phytoplankton uptake and the hydrodynamic drag force of the cluster are absorbed into a second scale of consideration. Approaches for generating optimal arrangements under various physical constraints at this (medium) scale are presented and compared, following the objective of maximising collective phytoplankton uptake. It is found that branching structures are optimal in limited domains of unidirectional flow, nets perpendicular to unidirectional flow are more efficient in larger areas and spirals are optimal in flow of varied direction. Lastly, analysis of the efficiency of some presently used structures is given, along with methodological suggestions for integrating the optimisation process into large scales, such as an aqua farm in a bay environment.