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What was New in Version 5.1

The upgrade to version 5.1 includes several significant improvements and bug fixes. The main changes and enhancements are listed below:

New features:

  • Wind Turbine components: This new Horizontal Axis Wind Turbine HAWT component has been designed to allow the modelling of wind turbines and the performance of coupled aero-elastic simulations. Aerodynamic loads on the blades are calculated through the AeroDeep routines that were developed by IFP Energies Nouvelles.

  • Line with bends: A Line component named Pipe with Bends has been developed which aims at making straightforward the setup of line which geometry includes straight and bent sections. Pipe with Bends components are designed to help users defining the geometry of spools using data simple to work with such as number of straight and bent sections, coordinates of section nodes and bend radii. In addition to the data included in the Generic Line components, the Pipe with Bends component includes an additional geometry dataset that is used to automatically generate the meshing.

  • DSS files architecture: The architecture of the DSS files that are used to visualize animations and store analysis outputs has been completely revised. The amount of data contained in these files has been reduced and now solely comprises data that are strictly necessary to perform post-processing tasks. This results in smaller files that significantly reduce the hard drive space requirements while offering faster access to analysis outputs.

  • Irregular waves directional spreading: Directional spreading is available for irregular waves modelled through a JONSWAP spectrum. Spreading is modelled through a cosn function. New data entry includes the number of directions, the spreading exponent, and the maximum angle range.

  • Load-excursion links: Load-excursion Link is a new component available in the user interface that may be used in mooring analysis to model the static and quasi-dynamic restoring force exerted at fairleads of a floating platform by any mooring line. Load excursions links are multi-linear springs which horizontal and vertical loads depend on the instantaneous horizontal and vertical distances between both end nodes. Input data related to each link must be pre-calculated and is then stored in text files. These text files may eventually be invoked by the user interface through these links.

  • Optimum density of contact elements: The density of contact elements is a parameter that controls the number of contact springs to be distributed along a contact zone. It is recommended to set this value equal to the inverse of the beam elements length for simple contacts like a pipe resting on the seabed. This requires that users calculate the optimum density of contact elements for every line segments. Setting the density of contact elements to zero in the contact input data now automatically asks the FE engine to consider the optimum density of contact elements, so that each node is in average - supported by a single contact spring.

  • Improved consistency of data in Analysis Sets: Consistency of input data series used to create LOG and DSS files from any Analysis Set is now enforced. Individual analyses included in the Analysis Set are indeed automatically re-generated when creating LOG and DSS files.

  • Dynamic point loads controlled through DLL routines: Dynamic point loads may be calculated through external dynamic link libraries routine owned by users. Such routines typically set calculated dynamic loads as a function of the position, velocity and acceleration of the node which can be used to model PID controls. This type of loads may now be invoked through the user interface using the Time-dependent via DLL load type.

  • Reference component for change in connection: The dis/connection displacement type that is used to change boundary conditions over the quasi-static or dynamic phase of an analysis has been enhanced. Dis/connection displacements now allow switching the connection from one component to another. It is for example possible to disconnect a Line end from one model component and further connect it to another model component. Connections between spaced out nodes also account for lever arm effects. This new feature has many potential applications like sequential installation and connection of spools.

  • Rigid Body Drawing components: Rigid Body components may now be excluded from the finite elements analysis when desired and be used for display purpose only in the 3D view window. An option has been included in the Rigid Body component to let the user select whether the component is to be used within the analysis as usual or if it is to be used solely for display. Rigid Bodies must be included within the analysis in case they are used to model contact with any Line component. Specifying that Rigid Bodies must be used for display only results in calculation time savings and reduced hard drive space requirements.

  • BOP post-processing: The data form listing the outputs from dedicated post-processing on blow-out preventers analysis sets has been moved into the Model Browser for more clarity.

  • Batch processing form: The name of the FE engine executable file that is to be considered to run the analyses that are listed in the queue is now echoed in the header of the batch processing form. This aims at avoiding any possible confusion in case a specific FE engine executable file was selected through the general Settings menu.

Improvements to the FE engine:

  • Enhanced control of maximum irregular wave height: Control of the maximum wave height to be encountered during a dynamic analysis including an irregular wave has been improved. The user interface enables for long specifying a lower bound for the maximum wave height through the desired Hmax/Hs ratio. It is now possible to specify both lower and upper bounds values for the Hmax/Hs ratio through the *WAVEHEIGHT keyword.

  • Separate added mass coefficient: Added mass coefficients CA is usually derived through the inertia coefficient CM as being CA = CM 1/. This relationship may be infringed for non-circular line sections, which therefore requires that the added mass coefficient is explicitly specified. Defining such added mass coefficients is now possible through the *COCA keyword.

  • Non-symmetric axial hydrodynamic loads along lines : The amplitude of hydrodynamic loads applied along the axial line direction usually does not depend on the flow direction, which is the reason why a single axial drag or inertia coefficient can be specified by default in the Line Segment Types. The FE engine now allows defining separate axial hydrodynamic coefficients for positive and negative relative fluid velocity through the *COADIR keyword.

  • Enhanced low frequency dynamic effects: Low frequency effects due to second order wave loads may be activated are usually activated through a Floater Motion type. These effects may now be activated within models which do not feature any Floater component through the *LFREQ keyword. This is for instance useful to model low frequency effects on structures made of beams only, like jackets, fixed wind turbine platforms or met masts.

Bug fixes:

  • NPD wind spectrum: The maximum period of NPD wind spectrum might on some instance be miscalculated. This has been corrected.

  • C ompatibility of internal fluid variation data with version 4.5: Internal fluid variation data applied to a line might not be properly assigned when opening a model that was originally setup with version 4.5. This does not impact the permanent internal fluid data.

  • Compatibility of external fluid data with version 4.5: External fluid data applied to a line might not be properly assigned when opening a model that was originally setup with version 4.5. This does not impact the permanent internal fluid data.

  • Deletion of Floater Motion Types: Floater motion types may sometimes be impossible to delete even if they are not assigned to any Floater component anymore.

  • User interface start problems: Launching the user interface by double-clicking a DSK model file through Windows Explorer would fail in case the working directory specified in the model does not match with the directory the model is stored in. Usual workaround is to start the user interface with the shortcut icon and then open the model file.

  • Import/export of groups of components: Exporting a group of components from one model to another may result in internal connections and names of sub-components being altered.

  • Clearance checks outputs: The time or step associated with the minimum clearance event that is reported within the outputs might on some instance be erroneous.