Modeling Extreme Stormy Conditions

[iosaaaa]

Hello,

I’m new to OpenFAST and am currently working on comparing the effects of marine growth on mooring lines under regular conditions versus extreme, stormy conditions. To simulate extreme conditions, I need to adjust the wave height and period, set the current to 1, and use waveMod = 2. Are there any additional inputs in the Hydrodyn file that I should modify?

In the InflowWind input file, I need to increase HWindSpeed and change WindType from 1 to a different value. However, it seems that for extreme conditions, if I want to use WindType = 3, I also need to include an additional file, such as one generated by TurbSim. What windtype should I set for extreme conditions, and what changes if any must I make to TurbSim file? Is there anything else I must change in inflow wind input file?

Thanks!

[jjonkman]

Dear @iosaaaa,

There are several inputs in HydroDyn that determine the incident waves and current, but the biggest difference between normal and extreme conditions would be the magnitude of the significant wave height (and corresponding period), as well as the magnitude of the current.

You can run extreme conditions both with steady wind and turbulent wind. The former is typically used if you are considering quasi-static response together with a dynamic amplification factor. But it is more common to use turbulent wind in OpenFAST for all design cases other than those with deterministic wind inputs (IEC gust cases like ECD, EDC, etc.). TurbSim can support both normal and extreme wind conditions defined by the IEC, as well as user-defined wind set ups.

See the HydroDyn and TurbSim documentation for more information.

Best regards,