## Richardson number and stability

Discuss the effects of turbulence on wind turbines and its simulation.

Moderator: Bonnie.Jonkman

Jian.Li
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### Richardson number and stability

In TurbSim, the RICH_NO is 0 for neutral atmospheric stability, >0 for stable and <0 for unstable.
However I find a Richardson number calculator using the critical Richardson number of 0.25 as the separation.
http://www.shodor.org/os411/courses/_ma ... index.html

I suppose I misunderstood something.

Bonnie.Jonkman
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### Re: Richardson number and stability

The critical Richardson number is the theoretical upper limit for turbulence to exist. It is different than the separation between the unstable/neutral/stable atmosphere.
Bonnie Jonkman

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National Renewable Energy Laboratory, 2003-2016

Anuj.Gupta
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### Re: Richardson number and stability

Sir, i am reading the Turbsim manual it is written there for the IEC kaimal model the RICH_NO =0 , a neutral atmospheric stability .and in the examples file which i downloaded from the site using a IEC kaimal model with a RICH_NO= 0.5. then what is the difference in them . Is there any effect of RICH_NO when we are using a IEC kaimal model ?

Bonnie.Jonkman
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### Re: Richardson number and stability

The RICH_NO input parameter (as well as everything else in the Non-IEC Meteorological Boundary Conditions section) is ignored in the IEC spectral models. Text in the summary file will indicate that the Gradient Richardson number is 0 for the IEC models, regardless of what the input file says.
Bonnie Jonkman

Envision Energy USA, 2016-
National Renewable Energy Laboratory, 2003-2016

Anuj.Gupta
Posts: 43
Joined: Thu Sep 27, 2012 6:53 am
Organization: Indian Institute of Technology Madras
Location: Chennai

### Re: Richardson number and stability

Thanks a lot sir . well i also find it yesterday after posting this