Dear Dr. Jonkman and NREL Team,
I am currently working with the IEA 22MW-RWT (Monopile) using FAST.Farm for a no-wave case. However, I am encountering an issue where my simulation does not proceed beyond 270 seconds out of 1200 seconds. The first 270 seconds took about 1 hour, but after that, the simulation has been running for over 30 hours without progressing further.
Previously, I ran the same case, and while it did progress till 1200 seconds , but the simulation failed to generate .out files for all three turbines.
Could you help me identify potential reasons for this issue? I have attached the relevant screenshots and a link to the files for reference.
Thank you for your time and support!
Best regards,
Virendra
IEA 22 MW FAST.Farm
Dear @Virendra.Patel,
When I click on your link, it attempts to download a large 700 MB+ zip file. Can you share the files in such a way that we can view / download only the most important files, such as the FAST.Farm (.fstf) and OpenFAST (.fst, .dat) input files?
I’m not sure why your simulation pauses at 270 s. Does it eventually move beyond that time? Is there anything peculiar in the wake or turbine response at that time that you can see in the output (.out) files or flow visualization (.vtk files) that could point to the problem?
Best regards,
Dear Dr. Jonkman and NREL Team,
Thank you for your response. I have now modified the folder to include only the necessary files as you mentioned. Please find the updated link here: https://drive.google.com/file/d/1YmoVXp8e1C46pXG0iX6vYa83emvQjd1V/view?usp=drive_link
Unfortunately No, the simulation remains stuck at 270s. It has been running for approximately 75 hours but has not progressed further.I checked the wake structure and turbine performance around this time, and everything appears to be behaving normally.
The .out files are generated correctlyas I did not notice any extreme fluctuations or irregularities in the turbine wake behavior.
Best regards,
Virendra
Dear Virendra,
I’ve now requested access to your Google drive.
Best regards,
Dear Dr. Jonkman
I have now modified the access settings, and you should be able to view and download the files. Please let me know if you face any issues accessing them.
Best regards,
Virendra
Dear @Virendra.Patel,
I can now access your files.
Can you also share the .out files from FAST.Farm and each OpenFAST model so that I can see if there is anything out of the ordinary in their response leading up to 270 s?
I would also suggest visualizing the flow computed by FAST.Farm, e.g., at hub height by setting NOutDisWindXY = 1 with OutDisWindZ = 170 m. Can you share the associated .vtk files?
Best regards,
Dear Dr. Jonkman,
I have now uploaded the FAST.Farm .out file as well as the .out files from each OpenFAST model.
These .out files were updated after setting NOutDisWindXY = 1 and OutDisWindZ = 170 m as suggested.
You can access them here: out and vtk files.zip - Google Drive
After re-running the simulation, I have generated and uploaded the .vtk files.
However, the simulation still does not progress beyond 270 seconds.
Additionally, I received the following warning:
WARNING: The requested output channel is invalid: Wave1Elev
FAST_InitializeAll:HydroDyn_Init:HydroDynInput_ProcessInitData: A requested output channel is invalid.
I appreciate your guidance in resolving this.
Best regards,
Virendra
Dear @Virendra.Patel,
Your .out files look like I would expect; the wind speed and rotor power starts dropping on the downstream turbines as the wakes from upstream turbines arrive.
I’m not sure if this is a sign of a problem, but your XY plane flow visualization looks a bit odd (here is the visualization at 270 s), because I would expect the wake region to not be so uniform in wind speed. I’m not sure what is causing this, but I would try things like switching from Mod_Wake = 2 (curled wake) to 1 (polar wake), disabling wake-added turbulence (WAT = 0), and increasing the discretization of the wake planes (increasing NumRadii and decreasing dr).
Regarding the HydroDyn warning that output Wave1Elev is invalid, this warning is triggered because this specific output was moved from HydroDyn to SeaState in OpenFAST v4.0, so, you can’t select this output from HydroDyn anymore.
Best regards,
1 Like
Dear Dr. Jonkman,
Thank you for your suggestions! I will update the FAST.Farm settings as recommended, remove Wave1Elev from HydroDyn, and re-run the simulation. I’ll let you know the results.
Best regards,
Virendra
Dear Dr. Jonkman,
I have now modified the FAST.Farm setup as per your recommendations:
so the HydroDyn warning (Wave1Elev) is resolved after updating the output selection.
However, the main issue still persists as the simulation remains stuck at 270s and does not progress further.
To possibility check, I also ran the simulation for a single turbine, but the problem remained unchanged.
Could you provide further guidance on troubleshooting this issue?
Thank you for your time and support.
Best regards,
Virendra
Dear @Virendra.Patel,
What impact did the following suggested changes have on the FAST.Farm simulation/results, including visualization of the XY flow at hub height?
- switching from
Mod_Wake = 2 (curled wake) to 1 (polar wake)
- disabling wake-added turbulence (
WAT = 0)
- and increasing the discretization of the wake planes (increasing
NumRadii and decreasing dr).
Best regards,
Dear Dr. Jonkman,
Thank you for your response.
As per your suggestion, we increased NumRadii and decreased dr.
Previous values: NumRadii = 17, dr = 28
Updated values: NumRadii = 25, dr = 20
Single Turbine Run: The simulation progressed until 802s, but then it got stuck. Since we record .vtk files every 15s, the last recorded step should have been 870s (58 × 15s). However, it seems that the wake computation stopped and crashed before reaching that point.
This suggests that the issue is not related to turbines 2 and 3, but rather something affecting the wake computation itself.
I have attached from first run screenshots for your reference.
Another Run (dr = 5m, Steady Wind Conditions): When reducing dr to 5m and using steady wind conditions, the simulation stopped at 98s, much earlier than before.
Best regards,
Virendra
Dear @Virendra.Patel,
It is interesting that the length of the simulation before it stops is tied to the spatial discretization. I assume these results are still with Mod_Wake = 2 and WAT = 1; is that correct? Does the simulation stop at the same time if you switch to Mod_Wake = 1 and WAT = 0?
What operating system are you running FAST.Farm on? Have you changed the FAST.Farm source code in anyway? Can you clarify if you are running an executable of FAST.Farm that is precompiled by NREL or something you compiled yourself?
Best regards,
Dear Dr. Jonkman,
Thank you for your response.
The results I previously shared were already with Mod_Wake = 1 and WAT = 0.
Before making the changes you suggested, I had already run tests with Mod_Wake = 2 and WAT = 1, but at that time, the simulation also did not progress beyond 270s.
I am running FAST.Farm on Windows. I have not made any modifications to the FAST.Farm source code. I am using precompiled NREL executable binaries.
Best regards,
Virendra
Dear @Virendra.Patel,
Thanks for clarifying. Indeed, your wake visualization makes more sense (not so uniform in deficit) after switching to Mod_Wake = 1 and WAT = 0. Not sure what was wrong with the Mod_Wake = 2 and WAT = 1 solution yet, but something to check if you decide to switch back.
One more question: With the variations you’ve made to the spatial discretization, is the length of simulation time until the simulation stops the same every time you run the simulation for a given spatial discretization?
Best regards,
