OC4 Phase I load case 1.0b

1 Test description

In this load case, we compare the eigenfrequencies of the OC4 Phase I model between Ashes and the participants of the project. The data from the participants can be seen in figure 4 from 

2 Model

The mode is the NREL 5-MW reference wind turbine mounted on the OC4 Jacket, as defined in 
It can be recreated using the offshore template and using the CSV file available here.

3 Results

The eigenfrequences of the model are solved and compared to those presented in the OC4 Phase I project. Note that the numbering of the eigenfrequencies in Ashes is from the lowest frequency to the highest, which is not the same as in the OC4 Phase I project. The table below summarises the numbering correspondance.

Mode number in AshesMode nameMode number in OC4 Phase I
11st global side-to-side2
21st global fore-aft1
31st drivetrain torsion3
41st asymetric flapwise yaw5
51st asymetric flapwise pitch4
61st flapwise collective6
71st asymetric edgewise yaw8
81st asymetric edgewise pitch7
92nd global fore-aft10
102nd glbal side-to-side11
112nd asymetric flapwise yaw12
122nd asymetric flapwise pitch13
132nd flapwise collective14
141st edgewise collective16
151st global torsion15

A bar plot with the eigenfrequencies from the different participants in the OC3 Phase II project and from Ashes is available on the following link.


Note that only a visual check is performed in that report. Once we have a set of results that are in agreement with the other participants, we use that set as a base case to compare the results produced by Ashes daily. If these results differ from more than 0.01% with the base, a failed test notification is raised. The  report can be found on the following link:

https://www.simis.io/downloads/open/benchmarks/current/OC4_Phase_I_LC10b regression.pdf