Bmodes download

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Florence.Haudin
Posts: 19
Joined: Fri Feb 08, 2019 3:11 am
Organization: Vulcain
Location: France

Bmodes download

Postby Florence.Haudin » Tue Jul 28, 2020 5:18 am

Good afternoon,
I am wondering where I can download Bmodes.
I could not find a working link.
Thanks in advance.
Best regards.
Florence Haudin.

Jason.Jonkman
Posts: 4952
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Bmodes download

Postby Jason.Jonkman » Fri Jul 31, 2020 10:30 am

Dear Florence,

As I announced here: viewtopic.php?f=38&t=1001, the NWTC Information Portal crashed before the replacement site is available. I've now shared the old BModes v3.00 archive, as well as the version known on this forum as BModes_JJ here: https://drive.google.com/drive/folders/ ... sp=sharing.

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

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Florence.Haudin
Posts: 19
Joined: Fri Feb 08, 2019 3:11 am
Organization: Vulcain
Location: France

Re: Bmodes download

Postby Florence.Haudin » Mon Aug 03, 2020 12:01 pm

Thanks Jason,
I am brand new with BMode so sorry in advance if my questions are basic.
I have 2 questions. I want to have the modes for the system considered in OC6 phase 2, tower + monopile considered as a land-based system.
The first one is related to the mooring system stiffness matrix in .bmi file? Is it the way the model the connection with the ground for a land-based system as done in subdyn by introducing a boundary stiffness matrix ?

My second question is related to this section of the .bmi file :
Distributed elastic stiffness per unit length along a flexible portion of the tower length:
"
0 n_secs_k_distr: number of points at which distributed stiffness per unit length is specified (-)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 : z_distr_k [row array of size n_added_m_pts; section locations wrt the flexible tower base over which distributed stiffness is specified] (m)
595318000.0 1165208000 1129400000 1095553000 1059931000 1024493000 989209000 953643000 918718000 883287000 847803000 812541000 777187000 741870000 706616000 671440000 636229000 600957000 565919000 530470000 495081000 459574000 385327000 305479000 280059000 254125000 227500000 200112000 171927000 143115000 114173000 80184000 52237000 35561000 20912000 9000000 1156000 : distr_k [row array of size n_added_m_pts; distributed stiffness per unit length] (N/m^2)"

I am wondering what is the equivalent of that part in Elastodyn ?

Thanks in advance.
Best regards.
Florence.

Jason.Jonkman
Posts: 4952
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Bmodes download

Postby Jason.Jonkman » Mon Aug 03, 2020 1:28 pm

Dear Florence,

Here are my answers to your questions:

Yes, you can use hydro_K or mooring_K in BModes_JJ to represent the lumped (coupled springs, CS) stiffness of the foundation of the tower + monopile. But please keep in mind that hydro_K and mooring_K are applied at the platform reference point (0,0,0), so, you'll want to ensure that you don't set draft > 0 m. For example, for the OC6 Phase II system (DTU 10-MW turbine + monopile), you'll want to set radius = 145.63 m, draft = 0 m instead of radius = 115.63 m, draft = 30 m.

The distributed elastic stiffness per unit length feature available in BModes_JJ would be useful for modeling the foundation via a distributed springs (DS) representation. FAST v8 and OpenFAST do not currently support such a model. At one point we developed a customized version of FAST v7 that supported DS modeling of the foundation. This is discussed in the following forum topic: viewtopic.php?f=3&t=607, especially my post dated Feb 01, 2013, where I share an example UserTwrLd_DS.f90 file.

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

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Florence.Haudin
Posts: 19
Joined: Fri Feb 08, 2019 3:11 am
Organization: Vulcain
Location: France

Re: Bmodes download

Postby Florence.Haudin » Thu Aug 06, 2020 10:54 am

Thanks Jason,
I calculated the bending modes with Bmodes and the different coefficients of the 6th order polynomial with ModeShapePolyFitting.
I then copied the coefficients in the mode shape section of the Elastodyn Tower file.
But when I tried to run the simulation I got the following error message :
------------------------------------------------------------------------------------------
Running ElastoDyn.

FAST_InitializeAll:FAST_Init:ValidateInputData:OutFmt produces a column width of 13 instead of 10
characters.
FAST_InitializeAll:ED_Init:ED_ValidateInput:ValidateTowerData: Mode shape coefficients for tower
fore-aft mode 1 must add to 1.0.

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

Aborting OpenFAST.
------------------------------------------------------------------------------------------
Is there any restriction on the coefficients ?

Here are the values I got with ModeShapePolyFitting (I checked the polynomial coefficient of ModeShapePolyFitting : fits here attached )
---------------------- TOWER FORE-AFT MODE SHAPES ------------------------------
0.8777 TwFAM1Sh(2) - Mode 1, coefficient of x^2 term
-1.2037 TwFAM1Sh(3) - , coefficient of x^3 term
3.7952 TwFAM1Sh(4) - , coefficient of x^4 term
-3.7017 TwFAM1Sh(5) - , coefficient of x^5 term
1.2225 TwFAM1Sh(6) - , coefficient of x^6 term
-689.6822 TwFAM2Sh(2) - Mode 2, coefficient of x^2 term
713.3420 TwFAM2Sh(3) - , coefficient of x^3 term
-1026.2863 TwFAM2Sh(4) - , coefficient of x^4 term
1573.5238 TwFAM2Sh(5) - , coefficient of x^5 term
-569.8972 TwFAM2Sh(6) - , coefficient of x^6 term
---------------------- TOWER SIDE-TO-SIDE MODE SHAPES --------------------------
0.9189 TwSSM1Sh(2) - Mode 1, coefficient of x^2 term
-1.3624 TwSSM1Sh(3) - , coefficient of x^3 term
4.0968 TwSSM1Sh(4) - , coefficient of x^4 term
-3.9707 TwSSM1Sh(5) - , coefficient of x^5 term
1.3174 TwSSM1Sh(6) - , coefficient of x^6 term
79.5897 TwSSM2Sh(2) - Mode 2, coefficient of x^2 term
-74.2219 TwSSM2Sh(3) - , coefficient of x^3 term
99.7401 TwSSM2Sh(4) - , coefficient of x^4 term
-145.1723 TwSSM2Sh(5) - , coefficient of x^5 term
41.0643 TwSSM2Sh(6) - , coefficient of x^6 term
Many thanks in advance.
Best regards.
Florence Haudin.
Attachments
OpenFAST_Prescribing_Loads_at_Tower_Top.pdf
(1.01 MiB) Downloaded 3 times
mode_shapes.pdf
(142.1 KiB) Downloaded 4 times

Jason.Jonkman
Posts: 4952
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Bmodes download

Postby Jason.Jonkman » Thu Aug 06, 2020 1:45 pm

Hi Florence,

I would guess you just have a numerical round-off problem. Checking the first set of coefficients for the fore the first tower fore-aft mode, the sum of the coefficients is 0.99, not 1.

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

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov


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