# User Defined WindType in InflowWind

**URL:** <https://forums.nlr.gov/t/user-defined-windtype-in-inflowwind/9296>\
**Category:** Inflow Turbulence\
**Created:** [September 19, 2025, 12:30pm UTC](https://forums.nlr.gov/t/user-defined-windtype-in-inflowwind/9296 "2025-09-19T12:30:31Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Yoor.Thiziri](https://avatars.discourse-cdn.com/v4/letter/y/b5ac83/32.png) [@Yoor.Thiziri](https://forums.nlr.gov/u/Yoor.Thiziri)\
**Post date:** [September 19, 2025, 12:30pm UTC](https://forums.nlr.gov/t/user-defined-windtype-in-inflowwind/9296/1 "2025-09-19T12:30:31Z")

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Dear OpenFAST developers,

In the InflowWind user guide(link: [https://openfast.readthedocs.io/en/main/\_downloads/a231262e7763b4d61759ebe4e0fc30b2/InflowWind\_Manual.pdf](https://openfast.readthedocs.io/en/main/_downloads/a231262e7763b4d61759ebe4e0fc30b2/InflowWind_Manual.pdf)) , it is mentioned that for `WindType = 6` is user defined using the `UserWind` subroutine (to be supplied by and compiled by the end user; template file `IfW_UserWind.f90` is provided).

I have checked the github repository of OpenFAST for that Fortran file but I cannot find it. The online documentation does not seem to explain that option.

Could you please point me to an example or provide an explanation how to use the User defined WindType in InflowWind?

Best regards,

Y. Thiziri

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**Author:** ![Derek.Slaughter](https://avatars.discourse-cdn.com/v4/letter/d/46a35a/32.png) [@Derek.Slaughter](https://forums.nlr.gov/u/Derek.Slaughter)\
**Post date:** [September 19, 2025, 1:48pm UTC](https://forums.nlr.gov/t/user-defined-windtype-in-inflowwind/9296/2 "2025-09-19T13:48:38Z")

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@Yoor.Thiziri

I apologize, the documentation hasn’t been updated to reflect the changes to InflowWind with regards to the user defined flow field. An issue has been filed on the OpenFAST github to get this fixed.

In the meantime, I can tell you where to look in the source code. The relevant locations are found in `IfW_FlowField.f90` on lines 1738 (`UserField_GetVel`) and 310 (`case (User_FieldType)`). Populate the subroutine `UserField_GetVel` with your code to provide the wind velocity vector based on time and position. Persistent data may be stored in the `UserFieldType` which is also passed to that subroutine. Members maybe be added to the `UserFieldType` by modifying the `IfW_FlowField.txt` registry file.

After this function has been populated, replace lines 316 and 317,

```auto
call SetErrStat(ErrID_Fatal, "User Field not implemented", ErrStat, ErrMsg, RoutineName)
return

```

which return an error stating that the user field hasn’t been implemented, with the call to `UserField_GetVel`.

Thanks,

Derek Slaughter

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**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\
**Post date:** [September 19, 2025, 2:06pm UTC](https://forums.nlr.gov/t/user-defined-windtype-in-inflowwind/9296/3 "2025-09-19T14:06:22Z")

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Here is a link to the issue in the OpenFAST GitHub repository: [Missing documentation for User Defined Wind in InflowWind · Issue #3000 · OpenFAST/openfast · GitHub](https://github.com/OpenFAST/openfast/issues/3000).

Best regards,

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**Author:** ![Yoor.Thiziri](https://avatars.discourse-cdn.com/v4/letter/y/b5ac83/32.png) [@Yoor.Thiziri](https://forums.nlr.gov/u/Yoor.Thiziri)\
**Post date:** [September 19, 2025, 2:09pm UTC](https://forums.nlr.gov/t/user-defined-windtype-in-inflowwind/9296/4 "2025-09-19T14:09:08Z")

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Dear @Derek.Slaughter ,

Thank you for the clarification. I will try to go through the code to understand it.

I wonder if there is an alternative way. My goal is to:

- Export a transient velocity field from a CFD simulation in the YZ plane slice from a post-processing tool like ParaView to some file format that can be read by InflowWind module (Could it be TurbSim or other file formats?).
- Use those inflow velocities as input to InflowWind each time step.

I am still learning OpenFAST and appreciate some guidance on how to achieve that.

Best regards,

Y. Thiziri

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**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\
**Post date:** [September 19, 2025, 2:15pm UTC](https://forums.nlr.gov/t/user-defined-windtype-in-inflowwind/9296/5 "2025-09-19T14:15:55Z")

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Dear @Yoor.Thiziri ,

Presumably you mean a time-dependent vertical YZ grid of inflow data (rather than a horizontal XY grid).

Regardless, I agree that you could always convert your CFD data to a format already supported by InflowWind, such as TurbSim, Bladed, or HAWC format.

Best regards,

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**Author:** ![Yoor.Thiziri](https://avatars.discourse-cdn.com/v4/letter/y/b5ac83/32.png) [@Yoor.Thiziri](https://forums.nlr.gov/u/Yoor.Thiziri)\
**Post date:** [September 19, 2025, 2:22pm UTC](https://forums.nlr.gov/t/user-defined-windtype-in-inflowwind/9296/6 "2025-09-19T14:22:48Z")

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Dear @Jason.Jonkman ,

Thank you for your answer. Yes, I mean YZ plane not XY.

Thank you.

Best,

Y.Thiziri