Without sustainable offshore aquaculture it is impossible to achieve food security
for coastal communities. Growing populations in coastal zones, amounting to
approximately 40% of the entire human population, exert high pressure on coastal
ecosystems and natural resources, and furthermore increase the need for
additional food sources. In coastal zones, marine-based nutrients offer great
potential to meet this demand. With sustainability in mind, extractive species like
mussels and oysters, which require no additional food, are becoming increasingly
more important. Therefore, researchers, industry representatives, and
policymakers alike are seeking to utilize offshore areas for shellfish aquaculture.
To successfully grow shellfish in offshore areas, it is vital to understand the
complex interaction of offshore aquaculture systems with waves and currents.
Modelling these interactions facilitates the development of aquaculture structures
that can withstand these high-energy environments. Therefore, the aim of this
thesis is to increase the understanding of the complex flow around offshore
shellfish aquaculture systems and their interaction with waves and currents. The
literature review reports on the hydromechanic drivers with a focus on the forces,
motion, and wave-structure interaction of bivalve aquaculture systems to lay a
sound basis for the analysis and interpretation of the results. From there, a lack of
information regarding the motions and forces of bivalve aquaculture components
in steady and oscillatory flow as well as a lack of guidance as to how the complex
surface of mussel dropper lines should be modelled is identified. To address these
gaps of knowledge, physical experiments with live blue mussels (Mytilus edulis),
substitute surrogate models, a newly designed aquaculture system, and naturally
floating islands were conducted. The results of these experiments, published in
four journal manuscripts, provide insights regarding the hydrodynamic
coefficients for mussel dropper lines and its influencing parameters. Furthermore,
the procedural design and creation as well as the hydrodynamic fit of a surrogate
structure are shown. Wave and current tests with the novel aquaculture system
and the comprehensive analysis of the hydrodynamic interaction of waves and
floating natural islands in a large-scale facility provide insights regarding the
motion and forces. Combined, the results enhance the understanding of the
hydrodynamic processes around bivalve offshore aquaculture structures.
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