CFD

windPRO works with a range of CFD tools, such as WAsP-CFD, OFWind, WindSim and Meteodyn.
EMD sells OFWind CFD licenses, WAsP CFD credits and operates the CFD calculation cluster.

WAsP CFD

The purpose of the WAsP CFD model in windPRO is to enable the windPRO user to calculate the wind resources in semi-complex or complex terrains.

Requirements for WAsP-CFD

WAsP CFD in windPRO works much the same way as a traditional WAsP analysis and it needs the same data for the calculation, i.e. at least some wind data, a digital elevation model and a roughness model. Due to the very demanding nature of the CFD calculations, the actual CFD analysis is made on the Cerebrum highperformance computer cluster operated at EMD.

The model is capable of calculating both a wind resource maps and individual wind turbine positions, but the actual CFD-analysis is always done in tiles with the central domain sized 2 km x 2 km.

In order to operate the WAsP-CFD in windPRO you will need:

  • WAsP 11 (or higher)
  • windPRO 2.9 (or higher)
  • WAsP CFD Calculation credits

 

WAsP CFD Calculations Credits costs EUR 100 per credits as well as we also offer different EMD WAsP CFD subscription options. WAsP CFD Calculation credits can be purchased from EMD – either online or by contacting sales@emd.dk

 

 

 

Terrain data for the CFD-analysis

The WAsP-CFD analysis is very similar to the WAsP analysis and it requires the same data – but with an extended 20 km distance requirement for the orography. In this guide we assume that you have already prepared the data for WAsP, so our assumption is, that you have already process your wind data, made a roughness-classification as well as added the height contours within an eight km distance from the site.

Now, the terrain data needs to be prepared for the CFD analysis, as the CFD model requires the orography in a distance not less than 20 km from the site. The WAsP CFD model consumes height contours (not gridddata). These contours can be stored or created from either in a line-object or in a grid-elevation object. Please note, that WAsP CFD is able to handle not more than two million points. windPRO will check if your terrain data meet this requirement.

Orography in a Line Object

Assuming that you have your ‘normal’ WAsP orography data in a line object covering a distance approximately 10 km from your site, then just press the ‘extend’ button in the line object to add the extra contours to your existing local data. In the far field, the 10 m or 20 m contour separation is fully sufficient.

Contours in a Grid Elevation Object

If your original elevation data originates from gridded sources, then it may be advanteous to store the data in a grid elevation object. If your data covers a distance less than 20 km from the site, then you must add more data from other sources such as SRTM. It is sufficient if you use a contour separation of 10 m or 20 m in the out zones.

Roughness Lines

Roughness lines should cover an area not less than 20-30 km from the site.

EMD WAsP CFD Subscriptions in windPRO

Flexible, fast and cost-effective access to run CFD calculations directly in windPRO
The EMD WAsP CFD subscription is a unique service for companies wishing to have continuous and flexible access to run high- resolution CFD calculations without any investments in own software, computer resources or in-house expertise. The service is available at very attractive prices directly from windPRO. Calculations are executed on the EMD High Performance Computer (HPC) Cluster using the WAsP CFD model developed by DTU.

The EMD WAsP CFD subscriptions are offered as annual subscriptions at fixed prices with a specified number of WAsP CFD calculation credits included.

Each WAsP CFD calculation credit allows you to make a CFD calculation for a tile of 2 km x 2 km on the EMD HPC cluster. The tiles are easily defined in windPRO. A complete WAsP CFD calculation for a “standard” project site will typically require three to six tiles, depending of the project size. The CFD results are usually delivered to your computer within a few hours after the calculation has been submitted to the EMD HPC cluster.

It is important to mention that when submitting a WAsP CFD calculation to the EMD HPC cluster, you are only sending terrain and roughness data, no confidential site wind measurements have to be sent to the cluster.

User benefits

  • High-resolution CFD calculations based on the WAsP model experience, the industry-standard flow model for energy yield calculations.
  • No need to invest in own expensive in-house CFD software license.
  • No need to have dedicated in-house CFD expertise and skills.
  • No need to invest in own expensive in-house high-performance computer resources.
  • Delivery of WAsP CFD results are typically within hours compared to several days or more when using own in-house CFD calculation resources.
  • CFD calculations seamlessly integrated with windPRO for energy yield calculations and site suitability analyses.
  • Easy sharing of CFD results with your colleagues through windPRO.
  • Flexible subscriptions terms allowing you to handle varying demands for your CFD calculations.
  • Very attractive prices compared to other CFD alternatives for performing high-quality and high-resolution CFD calculations on your projects.

 

 

Subscription Types and Prices

The following annual EMD WAsP CFD subscriptions are offered:

Subscription type Subscription includes
Annual Subscription Fee
Mini
25 WAsP CFD Calculation Credits valid for use through the subscription period.
Maximum use per week: 10 WAsP CFD Calculation Credits
EUR 1,700
USD 2,040
Small
50 WAsP CFD Calculation Credits valid for use through the subscription period.
Maximum use per week: 15 WAsP CFD Calculation Credits
EUR 3,200
USD 3,840
Medium
100 WAsP CFD Calculation Credits valid for use through the subscription period.
Maximum use per week: 25 WAsP CFD Calculation Credits
EUR 5,900
USD 7,080
Large
200 WAsP CFD Calculation Credits valid for use through the subscription period.
Maximum use per week: 35 WAsP CFD Calculation Credits
EUR 10,800
USD 12,960
Maxi
400 WAsP CFD Calculation Credits valid for use through the subscription period.
Maximum use per week: 50 WAsP CFD Calculation Credits
EUR 19,600
USD 23,520
Single credit   EUR 100
USD 120

 

How does it work?

All WAsP CFD calculation credits included in an EMD WAsP CFD annual subscription are added to your user account at the beginning of the subscription and can be used throughout the entire subscription period according to the weekly limitations of use shown in the price table.

The EMD WAsP CFD subscriptions have been designed to give the subscriber flexibility to run CFD calculations for both large and small project sizes and will also enable you to handle unexpected project work without having to change your subscription.

Unused WAsP CFD calculation credits will expire at the end of the subscription and cannot be carried forward to a new subscription. Latest two weeks before the end of the subscription, you will receive an auto-generated notification by e-mail, if you have unused calculations credits left in your account.

The subscription will start the following month after payment has been received and be valid for one year. However, the calculation credits are already released to your user account on the date of receipt of payment.

Upgrade from one EMD WAsP CFD subscription to a larger subscription type within the annual subscription period is possible by paying the price difference between the two subscription types; however, the original subscription date expiry remains unchanged. When upgrading, your account will be credited the difference of WAsP CFD credits between the two subscriptions + any remaining WAsP CFD credits from your original subscription. Downgrade of a subscription is not possible. Larger subscription options are available upon request.

Order your EMD WAsP CFD Subscription online here or contact sales@emd.dk for further information.

OFWind CFD

OFWind CFD is an OpenFoam CFD model specifically designed for use together with windPRO. Only a few steps are needed to run a CFD calculation with this powerful software combination:

  • Setup export of flowrequest in windPRO based on orography, roughness and WTG-area, optional define direction and heights.
  • Start OFWind and import flowrequest file. Choose Resolution – a compromise between accuracy and calculation time.
  • Modify wind directions for simulations if needed.
  • Start the fully automated simulation process, will typically run 3 to 7 days on a standard PC.
  • Automatically generated flowres-Archive import the simulation results back into windPRO.
  • Use the CFD results in windPRO for energy yield estimation and site suitability analysis.

 

What is OFWind CFD and how is it working?

OFWind CFD is a CFD-Tool to compute the flow field over a complex terrain. It uses the OpenFOAM libraries and applications from version 2.3.x. As input, OFWind CFD needs a flowrequest-Archive coming 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.

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 to be made. These simplifications regard 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 is 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, there is a flowdat-file for each direction containing information of the flow field above the WTG-Area. All these 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”. This can be imported back into windPRO to conduct predictions and analyse the flow field in the WTG-Area by the user. There is a strong graphic support 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.

Price

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 50% 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.

Exclusive Sales Representative

The OFWind CFD Model is available exclusively through EMD International A/S and its appointed windPRO representatives worldwide. Contact your local windPRO representative or EMD at sales@emd.dk for license ordering.

Flowreq & Flowres formats

If you are using a 3ʳᵈ party CFD tools such as WindSim or Meteodyn WT, you can save you a lot of time and resources by using .flowreq and .flowres files.

EMD has created the two open file formats to make it easy to export data from windPRO into a 3ʳᵈ party CFD and to import the flow-results back to windPRO. The flow-result file can be used together with the advanced Scaler features in windPRO to efficiently experiment with multiple turbine positions, hub heights, operation modes or even wind data .

This saves a lot of time and resources compared to running a full CFD simulation for every change.

Feel free to contact us for more information.