Difference between revisions of "Schwächen des WAsP-Orographiemodells (Englisch)"

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(Created page with "{{Hauptlink}} ===Elevation model pitfalls=== Based on many post construction evaluations, some trends are seen when doing a calculation in elevated terrain. The two major iss...")
 
 
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{{#ifeq: {{PAGENAME}} |Schwächen des WAsP-Orographiemodells (Englisch)|{{Hauptlink}}[[Category:Validierung]]}}
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===Elevation model pitfalls===
 
===Elevation model pitfalls===
  
Based on many post construction evaluations, some trends are seen when doing a calculation in elevated terrain. The two major issues are:
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Based on many post construction evaluations, some trends are seen when performing a calculation in elevated terrain. The two major issues are:
 
*In less steep terrain, higher elevated turbines are under predicted by the WAsP model relative to lower elevated turbines. With WAsP-CFD, similar results are seen, although there is some improvement.  
 
*In less steep terrain, higher elevated turbines are under predicted by the WAsP model relative to lower elevated turbines. With WAsP-CFD, similar results are seen, although there is some improvement.  
 
*In steep terrain (>30% slopes) higher elevated turbines are over predicted by the WAsP model relative to lower elevated turbines. The RIX correction can partially repair this problem, however, the WAsP-CFD, or other CFD models, would be a better choice than the WAsP model in this scenario.
 
*In steep terrain (>30% slopes) higher elevated turbines are over predicted by the WAsP model relative to lower elevated turbines. The RIX correction can partially repair this problem, however, the WAsP-CFD, or other CFD models, would be a better choice than the WAsP model in this scenario.
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[[File:DE_Energy_Validation(35).png|500px]]
 
[[File:DE_Energy_Validation(35).png|500px]]
  
'''Image: Ratio measured/calculated for a site in Germany with elevation differences'''
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''Ratio measured/calculated for a site in Germany with elevation differences''
  
  
Above is an example from a German site with turbines in elevation from 133m to 157m. A very clear trend is seen in that the turbines with lower elevation are over predicted relative to the turbines with higher elevation - an almost 7% per 10m elevation difference. Based on more internal calculation examples, the value varies from 3- 7% per 10m. '''This has high importance when having reference turbines with different elevations relative to the new project to be calculated.'''
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Above is an example from a German site with turbines in elevation from 133m to 157m. A very clear trend is seen in that the turbines with lower elevation are over predicted relative to the turbines with higher elevation - almost 7% per 10m elevation difference. Based on more internal calculation examples, the value varies from 3- 7% per 10m. '''This has high importance when having reference turbines with different elevations relative to the new project to be calculated.'''
  
  
 
[[File:DE_Energy_Validation(36).png|450px]]
 
[[File:DE_Energy_Validation(36).png|450px]]
  
'''Image: Example as in previous figure, but including WAsP CFD calculation'''
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''Example as in previous figure, but including WAsP CFD calculation''
  
  
Above is another example, with a less clear trend, but where WAsP-CFD is tested as an alternative to WAsP. For WAsP, a ratio of 7% per 10m is shown, as in the previous example. This ratio is lowered to 3% per 10m when based on WAsP-CFD.
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Above is another example, where WAsP-CFD is tested as an alternative to WAsP. For WAsP with Rix, a ratio of 3.5% per 10m is shown. This ratio is lowered to 3.4% per 10m when based on WAsP-CFD – almost no improvement.
  
 
For complex terrain (large steepness), see the [http://help.emd.dk/knowledgebase/content/TechNotes/TechNote_4_WAsPCFD_EMD_ValidationReport.pdf WAsP-CFD validation paper] on the EMD help desk website.
 
For complex terrain (large steepness), see the [http://help.emd.dk/knowledgebase/content/TechNotes/TechNote_4_WAsPCFD_EMD_ValidationReport.pdf WAsP-CFD validation paper] on the EMD help desk website.
 
[[Category:Validierung]]
 

Latest revision as of 17:49, 10 January 2023

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Elevation model pitfalls

Based on many post construction evaluations, some trends are seen when performing a calculation in elevated terrain. The two major issues are:

  • In less steep terrain, higher elevated turbines are under predicted by the WAsP model relative to lower elevated turbines. With WAsP-CFD, similar results are seen, although there is some improvement.
  • In steep terrain (>30% slopes) higher elevated turbines are over predicted by the WAsP model relative to lower elevated turbines. The RIX correction can partially repair this problem, however, the WAsP-CFD, or other CFD models, would be a better choice than the WAsP model in this scenario.


DE Energy Validation(35).png

Ratio measured/calculated for a site in Germany with elevation differences


Above is an example from a German site with turbines in elevation from 133m to 157m. A very clear trend is seen in that the turbines with lower elevation are over predicted relative to the turbines with higher elevation - almost 7% per 10m elevation difference. Based on more internal calculation examples, the value varies from 3- 7% per 10m. This has high importance when having reference turbines with different elevations relative to the new project to be calculated.


DE Energy Validation(36).png

Example as in previous figure, but including WAsP CFD calculation


Above is another example, where WAsP-CFD is tested as an alternative to WAsP. For WAsP with Rix, a ratio of 3.5% per 10m is shown. This ratio is lowered to 3.4% per 10m when based on WAsP-CFD – almost no improvement.

For complex terrain (large steepness), see the WAsP-CFD validation paper on the EMD help desk website.