Time taken for generating bts file

Hello everyone,

I am generating a bts file from turbsim. However, it takes more than 2 hours. I know that the parameters specified in the input file influence the duration time. But, i want to know whether more than 2 hours is reasonable for generating the bts file having the following parameters:

seeds: 2318573

#grids: 45
grid height: 260
turbulence model : Kaimal
turbulence type: NTM

BR

Riad

Dear @Riad.Elhamoud,

You haven’t stated enough information to gauge whether the time is reasonable in your case (the number of grid points and number of time steps are critical), but the following forum topic should be informative to you: TurbSim CPU Times.

Best regards,

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Dear @Jason.Jonkman ,

Thank you for your fast reply and thanks for suggesting the forum topic.
I was a bit worried about the simulation time but thankfully, it finishes after 5478 CPU seconds.

However, when doing a simulation with OpenFast, i get the following error:

FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption2:InflowWind_CalcOutput:CalcOutput:IfW_TSF
FWind_CalcOutput [position=(-3.8659, -146.25, 48.603) in wind-file coordinates]: FF wind array
boundaries violated: Grid too small in Y direction. Y=-146.25; Y boundaries = [-134, 134]

Frankly, i cannot understand why it generates a point at -146.25 and in the turbsim input file, the size of the width of the grid is 268 m so Y=[-134,134] ? And how to solve it ? should i regenerate a bts file ?

Best regards,

Riad

Dear @Riad.Elhamoud,

This error from OpenFAST means that an aerodynamic analysis node, which needs to know the ambient wind velocity from the TurbSim data you have specified, is located outside of the domain boundaries of TurbSim. It sounds like you believe a grid width of -134 to 134 m in Y is large enough in your mind for the OpenFAST application you are considering. So, do you know why there would be an aerodynamic analysis node located at Y=-146.25 m?

Best regards,

It seems to me that the wind turbine has done a translation in sway direction such that it exceeds the boundaries of the grid. Right ?

Hi Riad,

You can output the sway motion of the platform via output channel “PtfmSway” in ElastoDyn and check the last one you said (I assume you are running a floating wind turbine).

And in case you run it with Fast.Farm, maybe the bts file dimensions in Y-dir does not match your Fast.FARM domain size ? (I guess in that case you’d get the error right away when you try to start simulation)

Best regards,

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I agree with @Salur.Basbug’s comments, although it sounds like you are using OpenFAST, not FAST.Farm.

Another issue could be model instability (physical or numerical) that results in unrealistically large displacement. To better understand what is happening, it would be best to plot the times series of blade deflection, tower deflection, and floater displacement in multiple directions.

Best regards,

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Dear @Salur.Basbug

Thank you for your reply. That’s very kind from you.
In fact, i am working with OpenFast not with fast.farm
I tried your solution and that the in plane blade tip displacement was 41 m, that’s why it exceeds the boundary of the grid.

Thank you very much !

Best Regards,

Riad

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dear @Jason.Jonkman ,

Thank you for your reply. i am using openfast to model a FOWT.
In fact, i found that the in plane blade tip deflection was too high that it exceeds the domain boundaries.

Best Regards

Riad

Dear @Riad.Elhamoud,

An in-plane blade deflection that large sounds indicative of a physical or numerical instability with your OpenFAST model. This topic has been discussed many times on our forum before (use search).

Best regards,

1 Like