Meteorological codes for offshore conditions

Dear all,
I’m a new member of the forum, and I am honored to participate.
I’m an engineer PhD student and currently I am working on offshore wind energy systems ( in particular offshore wind turbine with floating foundation ).

I’d like to ask you same information and I hope to have your opinion on this issues:

  • To analyze the wind field of a site (onshore or offshore) which meteorological model have you used?
    In my work I referred to a CALMET (CAlifornian METteorlogical Model) as diagnostic model and I’d want to integrate it with a prognostic model to know the status of offshore weather condition in a specific site.
    For this reasons I have developed a numerical method ( using FORTRAN ) for the study and evaluation of wind potential of a site and its suitability for wind development.

Now I’m studying how to expand the code with the offshore conditions such us including model for the evaluation of currents and waves.

  • I also have to evaluate the effect of sea field on floating wind turbine.

Do you have any suggestions for my study?

Thank you very much!

Best regards

elvira

Dear Elvira,

This forum is meant for the design codes that we develop and maintain at NREL, which are available from: wind.nrel.gov/designcodes/. These codes are developed for wind turbine design, including the calculation of wind turbine performance, loads, and stability, as well as preprocessors to help build the models, postprocessors to analyze the reults, and utilities to run and manage the processing tasks. We don’t develop meteorological codes.

The aero-hydro-servo-elastic FAST with AeroDyn and HydroDyn code is the code we’ve developed for calculating the “effect of [the] sea field on [a] floating wind turbine.” More information is avaiable from: wind.nrel.gov/designcodes/simulators/fast/.

Best regards,

Dear Jason,

thanks for your answer.
I have seen codes FASTand Aerodyn. I’m already studying these codes a few weeks.
I also read several NREL’s works in particular I focused on "Dynamic modeling and analysisof loads an offshore floating wind turbines”, in which on page 14 it is written “… I use the term fully coupled throughout this work, to imply partially that the wind turbine’s response to wind and wave excitation in through the fully coupled structural-dynamic response. I do not use the term to imply That the wind inflow and sea-state condition need to be correlated …” so I tried to understand what type of wind and wave data are used in FAST and if it was possible to enter the fields of wind and waves not as separate input data but correlated together to improve the results.

I thought of integrating FAST with a code that can accurately predict the wind field and sea (and their correlation) in offshore conditions where there are no direct measurements.
I developed a meteorological model that uses as input data: hourly surface observations of wind speed, wind direction, temperature, cloud cover, ceiling height, surface pressure, etc. …
I have already developed a fortran code to assess the anemometer characteristics of on-shore sites where there are stations measure wind.
I Checked the onshore-code validity by comparing the results with remarks measured at the same site. The comparison showed the reliability of the code with excellent results. I’m currently reading the fast’users guide.

best regards,

elvira

Dear Elvira,

The statement you quoted was written to clarify that the coupled FAST with AeroDyn and HydroDyn code is not attempting to model the air-sea interface, which is a complicated multiphase fluid-flow problem. Instead, the coupled code models the wind and waves as separate processes that load the offshore wind turbine structure simultaneously; thus, the wind and waves both impact the loading and structural response of the offshore wind turbine.

AeroDyn relies on wind data that is read in from a file. These can be full-field stochastic turbulence data files created by TurbSim or simple time-history files of uniform wind data (what AeroDyn calls a “hub-height” wind data file format). HydroDyn has a built-in model for creating the wave data of either regular or irregular linear waves. For fixed-bottom offshore wind turbines, HydroDyn can also read in wave data generated by an external code.

Even though the wind and wave data are distinct inputs to the coupled FAST with AeroDyn and HydroDyn code, what we typically do is derive these data based on site-specific measurements. That is, for stochastic simulations, we choose the mean wind speed, significant wave height, and peak spectral wave period based on the long-term joint probability distribution at the specific offshore site. These three parameters are some of the main parameters that are needed to create the wind and wave time histories. So, even though the time histories of wind and waves are created separately, the main characteristics of the wind and waves (wind speed, significant wave height, and peak spectral wave period) can still be correlated.

I hope that helps.

Best regards,

Dear Jason,

many thanks for your answers, your informations were very useful to me. I’ll continue to study Fast and the other codes for offshore wind turbine.

bye bye

elvira