OFWind CFD is an OpenFoam CFD model specifically designed for use together with windPRO and exclusively sold by EMD.
OFWind CFD computes the flow field over a complex terrain. It uses the OpenFOAM libraries and applications from version 2.3.x.
OFWind CFD
Calculation Principles
As input, OFWind CFD needs a Flowreq file from windPRO with the following content:
- Orography map of your terrain
- Roughness map of your terrain
- Xml-Document containing the coordinates of your WTG-Area and desired wind directions and heights to compute and the spatial resolution the Flowres file is written into.
Based on the WTG-Area, OFWind CFD will cut a circular patch from the terrain with the WTG area in the middle.
The user can select how fine the orography is resolved inside the WTG area by setting the slider position to “Fast” (coarser resolution), “Middle” or “Accurate” (finer resolution).
Subsequently, OFWind CFD automatically generates a mesh which is needed to compute the flow over the terrain. The volume of the mesh resembles a cylinder to be able to compute the flow from each direction with the flow always perpendicular at the inlet.
The terrain around the WTG-Area influences the flow inside the park area. Therefore, not only the park area is used to create the mesh volume but also the surrounding of the WTG-Area.
Inside the WTG-Area a higher terrain resolution is used to compute the flow more accurately.
Calculation Process and Output
In order to be able to compute the flow field over the terrain on standard PCs and in reasonable time, a couple of simplifications have been made. These simplifications include for example the turbulence modelling and the assumption that the flow field is in a steady state condition.
For each cell the mass and momentum conservation are computed throughout the whole domain. This is done in an iterative process and calculation time depends on the number of cells inside the domain. The iterative process of solving the equations in OFWind CFD for each cell ends when a steady state is reached.
Once each direction has been simulated, OFWind CFD stores the following data at each park area grid position into files called “SiteName_Direction.flowdat” containing:
- Horizontal wind speed
- Turn
- Turbulence intensity (TI)
- Inclination
After simulating all directions, a flowdat-file exists for each direction containing information of the flow field above the WTG-Area. All flowdat-files are stored together into an archive inside the directory specified by the user in the “Output” pane at the top of the graphical user interface. This archive is called “.flowres” and can be imported back into windPRO to conduct predictions and analyse the flow field in the WTG-Area by the user. A strong graphic support is included in windPRO for illustration of the Flowres files content.
The resolution and heights chosen when generating the Flowreq file from windPRO define a three-dimensional grid above the WTG-Area. This is used when OFWind CFD sample the simulation data for the result files.
Pricing
| Perpetual license | One-Year License | |
| Standard OFWind CFD License (up to 4 cores) | EUR 5,500 | EUR 2,200 |
| Optional price – Up to 16 core utilization in OFWind CFD | EUR 1,250 | EUR 500 |
| Additional OFWind licenses within same company | 40% of first license price each | |
| Half day online training | EUR 500 | |
| Telephone support (advanced) exceeding normal support | EUR 110 per hour or EUR 1,200 for an annual subscription | |
OFWind CFD licenses include 1 year of free service (program updates and hotline support). The annual service fee for continued service on perpetual licence is 20% of the current valid list price for the software license(s) supplied.