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What's new in this version |
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What's new in this version |
| Warnings: | When opening existing model files that were prepared by older versions of OrcaWave, beware of compatibility issues. Binary data files have strong version compatibility features. When OrcaWave opens a binary data file written by an earlier version of the program, it is usually able to ensure that the data are interpreted exactly as they were by previous versions. If it cannot do so, it displays a warning. On the other hand, no such version compatibility is available with text data files. Text data files prepared with old versions may not load in new versions, or may load but be interpreted differently. Because of this we recommend that you use the binary data file to transfer models between different program versions. The OrcaFlex convert text data files tool can be used to ease this process. |
| When performing restart analyses, beware of compatibility issues if the parent model was run in a different version of OrcaWave. The best practice is to run both parent and child models in the latest available version of OrcaWave. |
A more in depth discussion of the major new features introduced in 11.4 is available on our blog.
This bug is fixed in version 11.4c.
This bug is fixed in version 11.4b.
OrcaWave can now analyse models in which a structure is divided into multiple sectional bodies – defined as bodies for which the wet body surface may be open-ended. The principal motivation is to enable multi-vessel OrcaFlex models which study dynamic connection loads within a large structure.
In models with sectional bodies, it is possible for a waterline to be associated with multiple bodies. Likewise for interior surfaces and displaced volume. Therefore the hydrostatic results available for a sectional body differ significantly from a conventional body with a closed surface, which we refer to as a displacement body. In particular, there is no volume or centre of buoyancy, and the hydrostatic stiffness matrix has more non-zero coefficients. Quadratic loads also differ between displacement and sectional bodies, since they include hydrostatic terms.
A parallel development in OrcaFlex 11.4 allows the new hydrostatic results to be used by an OrcaFlex vessel type.
OrcaWave can now compute mean drift loads using the momentum conservation method (also known as the far-field method).
Results are limited to horizontal (surge, sway and yaw) mean drift loads. Further, in a multibody model, it does not give loads on individual bodies. In other respects momentum conservation is closely related to control surface integration and, like that method, it often has good mesh convergence properties.
OrcaWave can now automatically generate meshes for control surfaces and free surface panelled zones:
These options are alternatives to using user-specified mesh files. The mesh details spreadsheet has been extended to include control surface panels and the free surface panelled zone as part of this development.
These automatically generated meshes can be saved as WAMIT .gdf files by using the popup menu on the mesh view or mesh details pages.
OrcaWave can now detect field points that are inside a body. There is no meaningful sea state RAO result at such points, so OrcaWave can optionally return a simple ? placeholder instead. A parallel development in OrcaFlex 11.4 allows these placeholders to be interpreted appropriately in that program.
We have improved the workflow for rigidly-connected bodies. In previous versions, external stiffness data was required to capture the effect of a mean (i.e. zeroth-order) connection load on the first-order equation of motion. The stiffness data could be obtained using the vessel mooring stiffness report in OrcaFlex, but the workflow was unsatisfactorily complex. OrcaWave now fully accounts for the connection load between parent and child, so you do not need to provide any external stiffness data as a result of specifying a connection.
Results for displacement RAOs (and quantities dependent on them) will be affected for models with rigidly-connected bodies if the mean connection load is non-zero. That is, if the connection load is non-zero when the child and parent are in their mean positions in the absence of waves.
| Note: | You can adapt an OrcaWave model from a previous version of the program to fit the new behaviour by modifying the external stiffness data for connected bodies. If there are no external mooring lines, the external stiffness matrices of parent and child should be zero. If mooring lines are present, new external stiffness matrix data can be obtained using the vessel mooring stiffness report in OrcaFlex 11.4a or later (the mooring stiffness calculation was updated in OrcaFlex 11.4a for this purpose). |
You can now specify different drawing data for each body in a multibody model.
We have improved the performance of the triangulation method for adding interior surface panels to remove irregular frequency effects. Improved performance will be seen in models with large body meshes.
OrcaWave now uses an improved method for estimating the first irregular frequency if your model includes validation of panel arrangement. This will affect warning messages about irregular frequencies if your mesh does not include interior surface panels.
In previous versions of OrcaWave, there was a requirement that mesh files should provide panels on the positive side of any symmetry planes. That requirement has been removed.
If your model is a restart analysis, OrcaWave uses a new approach for validating that the calculation mesh is identical to that of the parent model. A parent results file (.owr) from a previous version of OrcaWave will not contain the information required to satisfy this validation, so will need to be re-run in version 11.4 to be used by a restart model.
We have improved the performance of mesh construction. Models with large meshes will benefit, e.g. when opening the mesh view, mesh details or validation pages in the user interface.
This bug is fixed in version 11.3f.
These bugs are fixed in version 11.3d.
The mesh details spreadsheet has been extended to include mesh file panel indices.
This bug is fixed in version 11.3b.
A more in depth discussion of the major new features introduced in 11.3 is available on our blog.
OrcaWave models can now include dipole panels – used to describe structures which are thin and have water on both sides, such as fins, keels, heave plates etc. The radiation and diffraction effects of the thin structures are captured in the calculation, including a pressure discontinuity between the water on opposite sides.
The solve type is restricted to potential formulation only if the model involves dipole panels. All first-order results are available including added mass and damping and all RAOs. Panel results are extended to include the pressure jump across dipole panels. The only second-order results that are available are mean drift loads via the control surface integration method.
In previous versions of OrcaWave, the following all required the solve type to include the source formulation. They have been extended, motivated by the desire to provide comprehensive functionality for models with dipole panels (which cannot include the source formulation).
For some models, this will mean it is now possible to solve the potential formulation only, having previously required the source formulation. This will be beneficial for the run time and the memory requirement of a calculation. Results related to the above items will be affected by changing the solve type, but the impact will generally be small (at the level of the discretisation error of the mesh).
You can now choose to include mean drift QTFs in a full QTF calculation, even if zero frequency (infinite period) is outside the specified range of QTF periods or frequencies. This option is to assist users who want to restrict the QTF calculation to a band of frequencies (relevant to a particular dynamic analysis), but also require mean drift QTFs for use in static analysis.
Morison elements have been extended to provide added mass and fluid inertia forces, in addition to the existing drag force. This mirrors a parallel development in OrcaFlex 11.3
You can now draw mesh file panel indices in the mesh view. These make it easier to find the source data (in a mesh file) of a given panel, e.g. a problematic panel identified in validation message.
There is a new facility to compare two OrcaWave files and display the differences between their data. This feature will be familiar to users of OrcaFlex, which has identical functionality.
This bug is fixed in version 11.2e.
These bugs are fixed in version 11.2b.
A more in depth discussion of the major new features introduced in 11.2 is available on our blog.
The use intermediate results feature introduced in OrcaWave 11.1 has been re-named as restart analysis. The change tracking functionality introduced to OrcaFlex in 11.1 has also been introduced to OrcaWave to support both restart analyses and variation models.
Binary OrcaWave files (i.e. files with the .owd and .owr extension) created with the 11.1 use intermediate results feature will automatically be converted to the restart analysis model type when the file is opened by version 11.2. OrcaWave text data files (with the .yml extension) that use intermediate results will need to be re-created using 11.2, or converted using the OrcaFlex text data file conversion tool. Note that although the text data file conversion tool is implemented in OrcaFlex, it can handle OrcaWave text data files.
Model data can be edited in YAML text format directly inside OrcaWave by using the Model | Edit data as text menu item.
Because this new functionality has been designed to be as close as possible to the analogous functionality in OrcaFlex, the OrcaFlex user group webinar contains useful information that is directly applicable to OrcaWave.
OrcaWave models can now include Morison elements – rigid cylinders which attract hydrodynamic drag forces. Since Morison drag is quadratic, stochastic linearisation is performed to obtain a linearised drag model which can contribute to the first-order equation of motion. Linearisation is performed for a given sea state, defined by a wave spectrum.
The linearised drag will affect results for displacement RAOs (and quantities dependent on them, such as QTFs); drag does not affect results for load RAOs, added mass or damping. A typical application is a full QTF calculation in a situation where hydrodynamic drag has a significant effect on body motion: drag would be included in order to improve the displacement RAOs, and hence the QTF results.
Decomposed panel results have been added to the panel results that can be accessed via the API. Panel pressure (or velocity) is decomposed into separate contributions from the diffraction potential and the components of the radiation potential.
In previous versions, body data relating to inertia (either a radii of gyration matrix or a moment of inertia tensor), external stiffness and external damping were specified relative to the body origin. New data items allow you to specify values relative to an origin of choice (e.g. the centre of mass).
Results for load RAOs, displacement RAOs, added mass and damping can now be reported relative to an origin of choice for each body. This is intended to assist users who are comparing against results from other programs. The new functionality is accessed via the API. It only affects the reporting of results; it does not affect the calculation.
These properties, reported in the hydrostatics results, are now included in the mesh details spreadsheet as well. This means they are available before running a calculation.
A new data item allows you to specify that a body is rigidly connected to another body. This allows you to model the separate hulls of a semisub, catamaran or similar as separate bodies. A connection affects the displacement RAOs of both bodies, and all the result quantities that depend on them, such as QTFs. The principal motivation is users performing multi-vessel OrcaFlex analyses in order to study dynamic connection loads.
| Note: | Each body must be a closed surface, separate from other body surfaces. It is not possible to divide a single hull into multiple sections using this functionality. |
This new data item controls the method to compute the centre of buoyancy and hydrostatic stiffness matrix of a body. The new analytic method is motivated by the connections feature. It gives more precise self-consistency between some equivalent calculations, e.g. a multibody model with connections and an equivalent single-body model.
Support for Wavefront .obj files has been added.
A free form multi-line text field named comments has been added. This can be used to store notes about the model. OrcaWave does not use this text.
These bugs are fixed in version 11.1d.
These bugs are fixed in version 11.1c.
This bug is fixed in version 11.1b.
A more in depth discussion of the major new features introduced in 11.1 is available on our blog.
A recording of the OrcaWave 11.1 user group webinar can be viewed here: OrcaFlex 11.1 UGM - OrcaWave new features.
Roll damping results have been added which show the level of roll damping, relative to critical, for each body. A new data item allows you to specify a target percentage, in which case OrcaWave will increase the external roll damping coefficient to meet the target.
OrcaWave can now use intermediate results from a previous analysis to perform an accelerated calculation. The body mesh, wave periods and other fundamental input data must match the parent model – these data values are loaded from the parent model and cannot be edited. However, many data items can be edited in the child model and analysed with a much faster calculation. For example:
New data items have been added that allow you to reduce the number of second-order loads that OrcaWave will compute:
OrcaWave can now, optionally, divide non-planar quadrilateral panels when it imports them from a mesh file. Each divided panel becomes two triangular panels. The default behaviour (project the mesh file vertices onto a common plane and create a single panel) is unchanged.
When asking OrcaWave to add interior surface panels to remove irregular frequency effects, a new option allows you to choose how the panels are generated. The radial method is the method used by previous versions of OrcaWave. The new triangulation method often performs better for waterlines with a large aspect ratio (e.g. a typical ship). In addition, it can handle both moonpools and highly concave waterlines, whereas the radial method breaks down for those cases.
We have improved the method for handling non-planar mesh file data. If the mesh file data includes a panel edge lying exactly in the free surface, OrcaWave detects this and classifies the edge as a waterline segment, instead of using the general classification method (comparing the projected coordinates against the waterline Z tolerance). The modified method applies to bodies with zero heel and trim angles, and to coordinates with $z=-Z_{\textrm{MP}}$ in the mesh file, where $Z_{\textrm{MP}}$ is the body's mesh position Z.
This change extends the behaviour introduced in version 11.0b. In version 11.0b, classification using mesh file coordinates only applied to bodies with $Z_{\textrm{MP}}=0$. This change extends the functionality to include bodies with $Z_{\textrm{MP}}\neq 0$.
We have corrected some errors in the treatment of bodies with moonpools by previous versions of the program. Results for second-order loads are affected. Specifically, the results for water plane area, centre of floatation and water plane moments were incorrect. These quantities are used directly for calculating quadratic loads. Second-order loads also contained more subtle errors if an extended mesh was used to remove irregular frequency effects (because, in this case, the source formulation uses waterline information to determine $V(\vec X)$). First-order load results are not affected by these changes. In addition, bodies with moonpools are now supported by the option to add interior surface panels, as noted above.
This bug is fixed in version 11.1a.
These bugs are fixed in version 11.0g.
These bugs are fixed in version 11.0f.
These bugs are fixed in version 11.0e.
Support for Gmsh .msh files has been added.
These bugs are fixed in version 11.0d.
These bugs are fixed in version 11.0c.
We have improved the method for handling non-planar mesh file data. If the mesh file data includes a panel edge lying exactly in the free surface, OrcaWave detects this and classifies the edge as a waterline segment, instead of using the general classification method (comparing the projected coordinates against the waterline Z tolerance). The modified method applies only to bodies with zero mesh position Z and zero heel and trim angles, and to coordinates with $z=0$ in the mesh file.
Support for Hydrostar .hst files has been added.
These bugs are fixed in version 11.0b.