CFL error after enabling windfarm_opt=1 in 1-km domain with dense wind turbine deployment

[Guosen]

Hello,

I am conducting WRF sensitivity experiments using the Fitch wind farm parameterization by setting windfarm_opt = 1.

After enabling windfarm_opt = 1 in my 1-km domains, the July simulation stopped due to CFL errors. In contrast, the control simulations without windfarm_opt = 1 ran successfully for both January and July. The January sensitivity experiment with windfarm_opt = 1 also completed successfully.

For the problematic July case, I have attached my namelist.input and the relevant rsl.error.0182 file. I also checked the CFL locations, and they occur mainly in the wind farm region in d04.

The wind turbine parameters I used are:hub height: 105 m

rotor diameter: 175 m

standing thrust coefficient: 0.100

rated power: 5.3 MW

The turbine layout is relatively dense. In the densest wind farm area, there may be 3–4 turbines within a single 1-km grid cell. In total, about 1800 turbines are placed across three wind farms.

In my experiments, windfarm_opt = 1 was enabled in d04.

Could the CFL problem be mainly related to the strong wind farm forcing caused by the large rotor diameter and dense turbine distribution in the 1-km domain? Are there any recommended approaches to improve numerical stability in this situation?

Any suggestions would be greatly appreciated.

Thank you very much.

 

[kwerner]

Hi,
First, apologies for the delay. Since this is a few weeks old, can you let me know if this has been resolved yet? If not, it's possible the forcing is just stronger for that particular July case study, and it's strong enough to cause the CFL issues. See Segmentation Faults and CFL Errors and follow some of the recommendations to see if any of those modifications help you to get past the CFL errors.