Offshore Dynamics and CFD
Dynamic simulation of floating & immersed structures such as fish farms and undersea cables.
Working offshore represents a big investment in time, money and effort. Reduce your risk by simulating the effects of the ocean on your materiel.
Using the industry standard dynamics simulation abilities of Orcaflex by Orcina Software, we can offer you the ability to simulate the dynamics of a wide range of offshore structures and ship – materiel interactions.
Orcawave, a potential flow solver, is used to model the response of floating objects in waves (RAO data). The next step is to use Orcaflex to simulate the dynamics of the full sea-borne system including mooring lines, winches, cranes drag elements etc.
We have used our knowledge to help companies planning projects involving subsea cable installation, towed seismic arrays, floating fish-farm construction, craning operations from tenders and many more besides.
Orcaflex allows us to simulate such projects as:
- Offshore wind installation simulation
- Mooring
- Cable Caternary Paths
- Floating wind turbine and fish farm behaviour
- Cable laying
- Towed array sizing
Orcaflex allows us to simulate a wide variety of issues that are frequently encountered by the renewable energy industry.
- Installation of cables in monopile foundations
- Cable stress & strain
- Cable fatigue life estimation
- Vortex Induced Vibration
- Effects of marine growth over time
Our customers frequently require validating their designs or intended operations according to statutory codes of practice. We are most familiar with API and DNV codes of practice and certification, but we will work in accordance with whatever is required.
Orcaflex analysis of active ballast system on floating wind turbine
Flow analysis
We have experience with a wide variety of CFD-projects, and most of the common software’s used for fluid flow. At present we are mostly using OpenFOAM for free surface problems and Acusolve by Altair for most other analyses, as well as RADIOSS (also by Altair) for fluid structure interaction analyses (FSI). We have our own in-house HPC server suitable for CFD-simulations.
Slamming
Impact loads due to waves and/or motion are problems we have experience solving with CFD – also considering fluid structure interaction if necessary. A normal delivery from us would include the loads due to the slamming pressure from a set of load cases, and if desired the utilization of relevant structural parts.
Green sea
Analysing green sea is demanding due to its non-linear nature. Best results (not including model tests) are obtained with CFD-analyses, and we have the know-how to do this. A normal delivery from us would include results from several wave cases, and the pressure loads due to the water on relevant structural surfaces.
Using simulation to choose right mud agitator
A mud agitator is mainly used to agitate and mix the drilling mud to prevent solid particles from depositing in the tank. For proper mixing the mud agitator must be properly sized with respect to power requirement and impeller size.
Wave, wind and current loads
Simple potential theory can be used to obtain the wave loads in frequency domain if the wave loads are linear. However, if they are non-linear, more sophisticated methods must be carried out. We have the tools and competence to calculate non-linear wave loads. A normal delivery from us would include the wave loads on a selected structure for several load cases.
Wind and current loads, on for example super- and substructures of ships or platforms, are highly dependent on direction, and might be calculated with CFD simulations to find the values of drag coefficients. A normal delivery from us would include the wind/current loads or drag coefficients on a selected structure for several wind/current directions.
CFD of fish farm
Pulling a submarine out of a moonpool
An innovative way to lift heavy objects out of the water is to use a moonpool, which essentially is a vertical tunnel in the middle of the ship.
The advantage of a moonpool lift relative to a conventional lift is that the vertical force acts close to the centre of gravity, and thus generates much smaller pitch or roll moments to the vessel.
Linear potential theory and seakeeping analyses
We have much experience with linear analyses based on Response Amplitude Operators (RAOs). A typical delivery from us would include meshing of the geometry, calculation of the wave frequency response – also accounting
for second order wave drift loads – and often applying the results in further analyses. This usually involves tweaking the viscous damping loads based on model tests or CFD analyses and calculating the response in irregular waves, typically with mooring lines or other structural components connected to
the vessel. The simplicity and speed of such analyses makes them widely used, and the results are reliable as long as one knows when they are valid or not. The software we use for these types of simulations are OrcaWave and OrcaFlex by Orcina.
