Flexcom 8.10.4 |
 
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Flexcom 8.10.4 |
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The following faults are present in Flexcom 8.10.4. More detailed information on each fault is provided in the following sections.
No |
Issue |
Severity |
1 |
Floating body hydrostatic stiffness omitted from modal analysis |
Minor |
2 |
Shear7 interface includes coatings in strength diameter |
Minor |
3 |
Wave zone feature not available |
Minor |
4 |
Criteria feature incompatible with frequency domain simulations |
Minor |
5 |
Incorrect data echo for point load DLL |
Minor |
6 |
WAMIT data import |
Minor |
7 |
Summary collation ignores nodal velocities and accelerations during collation process |
Minor |
8 |
Flexcom Wind: Morison inertial loads applied by default to a floating substructure which may be undesirable |
Minor |
9 |
Flexcom Wind: For parked conditions, blade pitch angle reverts to 0° from 90° without control system model |
Minor |
10 |
Flexcom Wind: Tower drag |
Major |
11 |
Mode shapes presented in OUT file |
Minor |
•Related Topics: *FLOATING BODY
•Description: When Flexcom assembles the stiffness matrix for Modes, the hydrostatic stiffness terms are inadvertently overlooked, so the modal solver is effectively unaware of the floating body. Note that the issue does affect static or time domain simulations.
•Workaround: You could manually insert node springs or spring elements in order to compensate for the missing terms in the modal simulation.
•Related Topics: *COATINGS, SHEAR7 Interface
•Description: If you apply an external coating to an element, the coating diameter is passed to Shear7 as the strength. Coatings do not affect structural strength so the base diameter should be passed instead.
•Workaround: Manually edit the Shear7 input file before running the Shear7 simulation. Or simply avoid the use of coatings altogether by manually increasing the structural mass using standard geometric properties.
•Related Topics: *WAVE-GENERAL
•Description: If you specify a customised wave zone, the program ignores your input and uses the default wave zone size. This means that the wave zone always extends by half a wavelength below the mean water line.
•Workaround: No workaround exists but typically none is necessary.
•Related Topics: *CRITERIA
•Description: If you use the criteria feature to obtain a certain model configuration in a static analysis, and then perform a frequency domain dynamic analysis as a restart, post-processing results from the frequency domain may be unavailable.
•Workaround: Use the criteria feature to obtain the desired model configuration, then manually recreate the required model adjustments in a separate/unrelated static analysis, before proceeding to frequency domain dynamics.
•Related Topics: *LOAD
•Description: Input data echo for point loads applied via DLL may be incorrect. The node number quoted refers to the index/order of the node in the overall meshing scheme rather than the user defined node number. The issue is purely cosmetic and does not affect the simulation in any way.
•Workaround: None necessary.
•Related Topics: Hydrodynamic Data Importer
•Description: Data is imported from WAMIT files for one wave heading only.
•Workaround: Manually import the relevant RAO data, or repeatedly import a reduced set of data from a modified WAMIT data file.
•Related Topics: Summary Postprocessing Collation
•Description: The summary collation tool is capable of post-processing nodal displacements but ignores velocities and accelerations.
•Workaround: Manually collate the required information from the summary output (SUM) files.
•Related Topics: Flexcom Wind
•Description: For models built with the Flexcom Wind module, elements representing the floating substructure have a normal inertia coefficient of 1.0 (it is actually the added mass coefficient, which is typically set to zero by the user, plus 1.0). This means that during any dynamic simulations, there is an additional inertia term stemming from Morison’s equation which is undesirable. Given that users are typically using the radiation-diffraction approach to represent the majority of wave induced loads, they are using Morison’s equation to simulate viscous drag effects only. Therefore, the model should have non-zero drag coefficients only, with any added mass and inertia coefficients all set to zero.
•Workaround: Manually set the relevant inertia terms to zero in the main Flexcom keyword file.
•Related Topics: Flexcom Wind
•Description: For parked conditions, the blade pitch angle is typically initialised to 90° via the *AERODYN DRIVER keyword. If you are not modelling a control system (which would be very unusual), the blade pitch angle reverts to 90° at the beginning of the simulation.
•Workaround: Use ServoDyn to control the blade pitch angle at 90°, in addition to initialising it using the AeroDyn driver keyword.
•Related Topics: Flexcom Wind
•Description: Tower drag loads are based on relative velocity between the wind and the tower. Due to an error in he AeroDyn code, the computation uses tower displacement terms rather than tower velocities.
•Workaround: None.
•Related Topics: Modal Analysis
•Description: Occasionally the mode shape presented in the OUT file can differ from the Shear7 input file, due to a quirk in the normalisation process.
•Workaround: None, but none is necessary, as the mode shapes contained in the Shear7 input file are correct.