Using Mann Model for FastFarm Simulations

Dear NREL,

I hope this finds you well.

I recently ran into an error using Mann turbulence for a FastFarm simulation. I am trying to run a test case of two 15MW wind turbines. I am using the Mann model Python toolbox from this link: GitHub - jaimeliew1/ A Mann turbulence generator for Python written in Rust to generate the Mann inflow box. I generated a turbulence field using this toolbox with the following variables: [nx: 1024, ny: 256, nz: 128, Lx: 5115, Ly: 1275, Lz: 635] which are the inputs for the Python toolbox. These values yield a spatial discretization of 5m in all directions.

The toolbox then generated three “.bin” files, U_1234.bin, V_1234.bin, Z_1234.bin. I set up the FastFarm inflow.dat file as shown in the screenshot below. A screenshot of the “.fstf” file as well as the error message from running FastFarm_v3.5.2 are also shared below.

Additionally, is there any recommendation for selecting the low and high resolution discretization for the input file in FastFarm when using the Mann model? Should the discretization in both the low and high-resolution in FastFarm input file match that in the Mann box?

I would greatly appreciate guidance on this.

Kind regards.

InflowFile.dat file screenshot:

.fstf file screenshot:

Terminal error message:

Dear @Abdulbaset.Alazhare.

There was a bug in OpenFAST v3.5.2 that led to some models generating a stack overflow error: FAST.Farm · Issue #2053 · OpenFAST/openfast · GitHub. This will be fixed in the pending release of OpenFAST v3.5.3.

Unfortunately, there is still an open issue that prevents using Mann-based inflow in InflowWind (WindType = 5) with Mod_AmbWind = 3 in FAST.Farm–see: Bug Report: Combination of Mod_AmbWind=3 with WindType=5 in FAST.Farm · Issue #471 · OpenFAST/openfast · GitHub.

Best regards,

Dear @Jason.Jonkman,

Thank you for your reply.

Unfortunately, I am still getting a similar error message despite using the latest version of Fast.Farm (v3.5.3). I am using WindType = 5 & Mod_AmbWind = 3.

Any thought as to why I am still getting a similar error?

Kind regards

Error message:

Dear @Abdulbaset.Alazhare,

The issue associated with the stack overflow error for Mod_AmbWind = 2 or 3 with WindType = 3 should be fixed in the release of FAST.Farm within OpenFAST v3.5.3, but the issue in FAST.Farm associated with WindType = 5 is still open (Bug Report: Combination of Mod_AmbWind=3 with WindType=5 in FAST.Farm · Issue #471 · OpenFAST/openfast · GitHub).

Best regards,