Convergence Issues with TurbSim in User-Defined Time Series

Hi everyone,

I’m experiencing some inconsistencies while using TurbSim to create windfield inputs for OpenFAST, particularly when utilizing the user-defined time series option based on site data. Despite using identical input files and time series data, TurbSim occasionally encounters convergence problems.

In some runs, the output contains unexpected results, such as NaN or “****,” while other times the outputs are valid and align with the expected velocity components from the time series data.

I’m curious if this behavior is typical or if there’s a known issue that might be causing these intermittent convergence problems, especially when the input files and time series data remain constant.

Has anyone else experienced similar issues, and are there any recommended solutions or troubleshooting steps to resolve this? Any guidance would be greatly appreciated.


Dear @Hazal.Altug,

Are you saying you run TurbSim with the identical executable and identical input file at different times and obtain different results intermittently? I would not expect this at all. Did you compile TurbSim yourself or are you using a precompiled binary executable of TurbSim provided by NREL?

Best regards,

Dear Mr. Jonkman,

Thank you for your response. I’m currently using the precompiled TurbSim.exe provided by NREL, not a custom-compiled version. As mentioned earlier, I’m utilizing the same TurbSim input file (turbSim.inp) and a consistent time series data file across multiple runs. However, the results seem inconsistent.

While there are occasions when TurbSim correctly converges to the wind speeds specified in the time series data, there are also instances where the output contains “NaN” values or non-numeric placeholders like “**”.

Given that I’m using the same input configuration, these intermittent issues are puzzling. Do you have any insights into what might be causing this? Any suggestions for troubleshooting or resolving this inconsistency would be greatly appreciated.

Thank you again for your guidance. I look forward to your response.

Best regards,


Which version of TurbSim are you using? There have been some fixes to the user-defined time series for TurbSim in the OpenFAST GitHub repository. For example: TurbSim bug fix for user-specified time-series input files by bjonkman · Pull Request #171 · OpenFAST/openfast · GitHub and TurbSim: User-defined time series updates by bjonkman · Pull Request #1361 · OpenFAST/openfast · GitHub.

I don’t see precompiled TurbSim binaries of the latest releases, but there is one for v3.4.0. See the release assets here: Release OpenFAST v3.4.0 · OpenFAST/openfast · GitHub. You’ll just need to make sure your input file matches that version. (see openfast/docs/source/user/turbsim/examples at v3.4.0 · OpenFAST/openfast · GitHub for v3.4.0 example files)

Thank you for the information and the links to the resources. It turns out that I was using TurbSim version 2, which seems to be causing these intermittent convergence issues. After trying TurbSim version 3.4.0, I can confirm that the problem has been resolved, and the output is consistent without any NaNs or invalid characters.

I appreciate your guidance on this matter. Thanks again for your support!

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