Initial Condition for Wind Directions #3226
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Dear @Parrotyeon, Can you clarify, when you change the wind direction, are you also changing the nacelle-yaw direction to align the rotor with the wind? Regarding your specific questions:
Best regards, |
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Dear @jjonkman , Thank you for the advice 😄 Yes, I'm using vanilla "Discon_OC3Hywind.dll" for the simulation. Based on my simulation results, I found that when I set the initial blade pitch angle to 0 deg, the simulation no longer produced the fatal error that occurred with the previous initial conditions. However, I noticed that even though the initial blade pitch angle is 0 deg, the blade pitch converges to approximately 1.5 deg in the steady state. Is there any reason why the steady-state blade pitch angle settles around 1.5 deg, even though it's under rated wind speed? Best regards, |
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Dear all,
I am currently working on wind–wave misalignment cases using metocean data covering wind speeds from 0 to 25 m/s with various wind directions.
From my simulation experience, selecting appropriate initial conditions is very important — not only to minimize transient response time, but also to avoid potential fatal errors in OpenFAST.
To address this, I have been computing initial conditions under steady wind and still water conditions at every 10° increment of wind direction (from 0° to 180°) for each wind speed. However, my metocean dataset has a finer directional resolution, and I am unsure how to properly estimate initial conditions for wind directions that were not explicitly computed (for example, 53°).
Previously, I applied a simplified assumption:
I kept all states the same except for surge, sway, roll, and pitch, which I rotated as a vector according to the change in wind direction.
For example, if the original displacement was
[surgeo,swayo]=[8,0],
then for a 10° change in wind direction, I updated it as
[surgeo,swayo]=[8,0],[surgen,swayn]=[8cos(10∘),8sin(10∘)].
Then I ran OpenFAST until the mean values converged. However, this approach seems overly simplified, and in practice it required at least two iterations to reach convergence.
Therefore, I am considering constructing a more accurate estimation method by interpolating the initial conditions between two adjacent wind directions.
I am not fully confident that this is the correct approach. I also noticed that OpenFAST does not appear to provide a direct static equilibrium solver. I briefly considered using the linearization process, but I have not yet fully understood how it could be applied for this purpose.
Could anyone kindly provide advice on:
Any guidance would be greatly appreciated.
Best Regads,
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