PhD position in Marine Hydrodynamics
The Department of Marine Technology at NTNU has a vacancy for a PhD Candidate within marine hydrodynamics related to the topic: Wave and current load effects of moored closed aquaculture cages.
About the position
With motivation to avoid sea-lice contamination and reducing the environmental footprint of fish farming, closed fish containment systems (closed cages) have been developed and installed at several locations in Norway. Although most relevant for sheltered locations, wave and current exposure must still be considered. Common for the different concepts is the presence of a free surface inside the containment, typically covering a large fraction of the structure’s water-plane area. The restricted free surface means sloshing will occur when the cage is set into motion, for instance from external wave exposure. Sloshing has a significant influence on the structural responses and mooring loads, as documented in several research projects. Despite several studies, closed cages are still considered novel structures.
Previous relevant studies on closed cages have focused on a single cage. In this work, the candidate will consider several closed cages in an array. One must expect significant hydrodynamic interaction, both due to wave scattering from each cage, but also due to the wake from each cage. The purpose is to identify whether there are important interaction effects that must be considered in design of a closed cage farm. Closed cages are typically grouped based on their structural characteristics as rigid, semi-rigid (elastic) or fully flexible (membrane) structures. Hydroelastic effects of sloshing for the semi-rigid and flexible cage structures has been considered in several projects. A disadvantage with non-rigid cages is that there are more natural sloshing periods that can be excited by the structure. In the present study the focus will be limited to consider stiff, near rigid cages.
Research tasks include, but is not limited to:
- Investigation of potential flow theory models for wave-current interaction on floating bodies and hydrodynamic interaction between the cages in an array of cages. Rigid cages will be considered, such that hydroelastic effects can be neglected
- Development of time-domain simulation model based on potential flow theory for wave-current interaction for the case of low current speed (no flow separation)
- Investigation of the importance of flow separation, both regarding the loads on each cage directly and wake effects and attempt to account for this in a rational manner
- Experimental study with scaled models of closed cages in waves
The PhD candidate will be part of the SFI Blues, a Centre for Research-based Innovation hosted by SINTEF Ocean, funded by the Research Council of Norway. Being part of SFI Blues implies collaboration and frequent communication with research- and industry partners of SFI Blues. Active participation in the research community, including collaboration with other PhD students at the Department of Marine Technology Centre is expected.
The goal is a completed doctoral education up to an obtained doctoral degree.
You will report to supervising Professor and Head of Department.
Read more about the position and apply here!
Application deadline: 1st April 2022.