User Meeting 2024: Q&A

Questions and Answers that came up during the WindSim UserMeeting 2024

Here is a curated list of questions that were asked during the WindSim UserMeeting of 2024. The questions are in italics and they are grouped according to which presentations they are connected to.

Accelerator pre-processing

What are the accuracy of the maps from ESRI?

The resolution varies according to site. See map-data-sources.
WindSim is limited to 4000x4000 nodes, so best possible according to those limitations
Is it possible to customize the roughness and elevation data based on local knowledge when using the ESRI data?

Roughness values is possible.
Workaround using other tool should be possible.
On our radar
Do we have a limitation in the number of cells along the coordinates and vertical direction? Same as the big model version?

Same as the big model version.
Are all the stability bugs also fixed in desktop version?

Stability bugs here was more of the: 'Accelerator working as intended' - Projects completing as expected.

Not atmospheric stability, in case there was a misunderstanding.

The core (simulation engine) is the same for the Desktop and Accelerator, so improvements to core engine can easily be applicable for the Desktop as well.

Our plans for the desktop is not finalized yet, but it is still needed.
Is it possible to load your own custom maps?

Not currently, on the roadmap.
When using the ESRI data, is it possible to extract the used data for using it with other models? - It is critical to use identical input data when comparing different models.

It is possible to download the elevation as a geotiff, the roughness as a .png file through the files interface. Both elevation and roughness can also be downloaded combined in .gws file
Is it possible to enter tree height maps in meters without having to convert to roughness and back again?
Vegetation height and also Leaf Area Index could be useful for the canopy model

The first version of Accelerator forest will be a feature-wise copy of the desktop version. There is room for design and useability improvements, thanks for the suggestions.
How is the meso-correction performed (in Statkrafts beta-presentation), using WindSim or outside of WindSim? (familiar with the MMC in desktop version, but not on cloud version)

Ove used an inhouse meso-correction outside of WindSim
Are the thermal stability settings available in the Accelerator pre-processing?

Not in the current build. High priority to add.
A workaround is available using map-files from Accelerator and Desktop.

Recommended settings/Knowledge base

In the presentation and knowledgebase it was/is mentioned to better not use negative MOL values respectively run unstable cases. What would you recommend for such sites?
- Is there any alternative to get satisfactory results for unstable conditions without running with negative MOL values if the results with neutral conditions are not satisfactory?

We are uncertain of our methodologies in unstable conditions, it might work sometimes. One option that can be explored is getting the unstable effect through Mesoscale coupling.

- If modeling is done with unstable conditions anyway against the recommendation and even if no convergence is reached but the vertical profiles and cross-predictions are satisfactory, would you agree that this the more important quality factor to assess the windfield results than reaching convergence?

I agree that the cross-prediction and vertical are more important than the convergence. The windfields should have stabilized to some degree though.

In order to activate the stability option / adjust the with profile, there are some items than can affect the wind profile such as height of boundary layer, MOL, etc. each of them has an effect on the wind profile and result. is there any guidance which item should be adjusted first or what is the effect of each item on the wind profile and result?

Most important items which can affect wind profiles are stability and forest model (Forest can increase vertical wind shear). But We can not say which one is more important. It depends on your study area.

Rotor-equivalent wind speed

I have a question regarding Arne's presentation. When comparing the energy production between hub height and rotor equivalent wind speed, did you use exactly the same power curves? Aren't the power curves given by manufacturers explicitly defined for hub height velocity?

I used the same power curve.

Geosphere - WindSim beyond wind energy

Hi Ingo! When using the speed-up factors to calculate the v50-wind speed at each grid point, do you run the flow model with standard speed above boundary layer at 10 m/s, or do you run a model with a higher speed above the boundary layer to represent a more extreme case. I guess that may have an impact on the speed-up factors...

Did not try it out, it is a good idea

Mesomicro scaling approach

For MMC, would you still recommend using atmospheric stability or would you regard that is covered by Meso data (so neutral only run)?

To some degree it is covered by the Meso data.
In some cases where the Meso supplied boundary approach behaves properly, it might work better.
Would you be able to share an implementation example of the MMC?

Contact Juho and he can give you a HundHammer implementation and explanation.
Is the Meso a WRF model run in house at WindSim?
What are the necessery physical properties that a NEWA Netcdf file should include in order to be utilised by WindSim MMC?