Modelling Tower

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Joined: Tue Apr 21, 2020 2:06 am
Organization: Universität Bremen
Location: Germany

Modelling Tower

Postby Malte.Frieling » Mon Oct 26, 2020 3:06 am

Hi everyone,

I have a problem to model the tower. We simulate with OpenFAST V2.1.0 a site with a water depth of 30 m. Thereby we adapt the monopile to a diameter of 7 m. In a height of 10 m above still water level (SWL) is the transition piece (TP) with a height of 10 m. The diameter of the TP tapers from 7 to 6.5 m. The TP is to be modeled as part of the tower,which starts at 20 m above SWL up to a height of 87.5 m above SWL.

Monopile_Tower_Drawing.PNG (20.53 KiB) Viewed 125 times

Modeling the monopile is no problem. For the tower I adjusted the values in the ElastoDyn-Tower-File TwrFile and in the AeroDyn15 file the table "Tower Influence and Aerodynamics". But the visualization in Paraview still shows an offset between the monopile and the tower.

Monopile_Tower_Paraview.PNG (10.81 KiB) Viewed 125 times

Did I miss a setting for the diameter of the tower?

Best regards,

Malte Frieling

Posts: 5300
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO

Re: Modelling Tower

Postby Jason.Jonkman » Mon Oct 26, 2020 7:08 am

Dear Malte,

It sounds like you've specified the tower properly in ElastoDyn. The issue you've identified is a limitation of the surface visualization feature of OpenFAST. The surface visualization of the tower is based on the ElastoDyn inputs TowerHt and TowerBsHt, but because the tower diameter is not actually specified in ElastoDyn, the visualization assumes a given tower diameter and linear taper. This is mentioned in Table 4 of the FAST v8 ReadMe file, where the surface visualization features are summarized: ... sp=sharing.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
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