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OpenFAST / openfast

Main repository for the NREL-supported OpenFAST whole-turbine and FAST.Farm wind farm simulation codes.
http://openfast.readthedocs.io
Apache License 2.0
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The simulation of floating offshore wind turbines considering substructure hydroelasticity #1250

Closed JackyzhangHJ closed 2 years ago

JackyzhangHJ commented 2 years ago

Dear all I recently try to simulate the hydroelastic effect of the substructure of OC4 DeepCwind semisubmersible FOWT. From what I understand from the openfast user guide, it seems to be implemented mainly by modifying the input file of Subdyn. However, when I try to run openfast, it cannot open Subdyn. Do I need to make changes to other input files? And are there any relevant cases in the r-test folder for reference. The main input file and the Subdyn input file are shown below. Looking forward to your answers!

main input file.txt subdyn input file.txt

JackyzhangHJ commented 2 years ago

The error reported by openfast is shown in the figure. image

bjonkman commented 2 years ago

Is this the name of your input file? NRELOffshrBsline5MW_OC4DeepCwindSemi_SubDyn (without any file extension?)

Check that the main input file's value for SubFile (line 41) is set properly.

Here are OpenFAST regression test input files for the "Semisubmersible Floating System for Phase II of OC4": https://github.com/OpenFAST/r-test/tree/main/glue-codes/openfast/5MW_OC4Semi_WSt_WavesWN

JackyzhangHJ commented 2 years ago

Dear @bjonkman I have modified the main input file as you suggested. However, the following error occurs when running openfast. Which part of the Subdyn input file should I modify? Looking forward to your answers！

Running SubDyn. Floating case detected, Guyan modes will be rigid body modes Guyan extra moment and rotated CB-frame will be used (floating case detected) Performing Craig-Bampton reduction 1614 DOFs -> 10 modes + 6 DOFs [INFO] Negative eigenvalue found with small norm (system may contain rigid body mode) ...... FAST_InitializeAll:SD_Init:Craig_Bampton:CraigBamptonReduction:CraigBamptonReduction_FromPartition :EigenSolveWrap:EigenSolve:Zero eigenvalue found, system may contain rigid body mode

OpenFAST encountered an error during module initialization. Simulation error level: FATAL ERROR

Aborting OpenFAST.

jjonkman commented 2 years ago

Dear @JackyzhangHJ,

I would guess there is a problem with how you’ve set up your SubDyn input file, e.g. the member or joint definitions. Are all joints that you've specified interconnected by members?

Best regards,

JackyzhangHJ commented 2 years ago

Dear @jjonkman Thank you for your advice. I tried to do hydroelastic analysis for Spar platform (less number of members and joints than OC4DeepCwind). Openfast works fine with SubDyn. Thanks again for your suggestion.