OrcaFlex 8.3

The latest release of OrcaFlex 8.3 is OrcaFlex 8.3d. To upgrade to OrcaFlex 8.3d, download the following zip file:
OrcaFlex-Patch-8.3a-8.3b-or-8.3c-to-8.3d.zip (1.7 MB)
and then run the program that the zip file contains.

This patch can only be applied if you are currently using an earlier release of version 8.3.

The new features introduced in OrcaFlex 8.3 are described below. For full details please download the following zip file: FlexHelp.zip (865 KB) and save the files it contains. You can then open the saved .hlp file and open the What's New topic in the Introduction chapter of the contents, and follow the links from there to other parts of the help file.

New in Version 8.3d (released November 2003)

VIV Toolbox

A change has been made to the Vortex Tracking (2) model. Previously this model did not include any of the vortex strength decay effect that is present in the Vortex Tracking (1) model. But trials have revealed that omitting this effect causes the Vortex Tracking (2) model to over-predict response when the Strouhal frequency is high compared to the natural frequency. The Vortex Tracking (2) model therefore now includes vortex strength decay, using the same method as in the Vortex Tracking (1) model.

Bug fixes

In certain circumstances OrcaFlex was crashing when a password protected screensaver started. This problem has now been fixed.

New in Version 8.3c (released September 2003)

Bug fixes

In OrcaFlex 8.3a and 8.3b there were some problems with the new vessel RAO and spectral response reports. The RAO phases and the spectral results were sometimes reported incorrectly.
Spar Buoy and Towed Fish Line attachments were being drawn in the wrong place when the model was in Reset state.
When using the VIV Toolbox, range graphs of VIV results gave an error if VIV was disabled for part of the line.

New in Version 8.3b (released July 2003)

Bug fixes

Simulations which used Calculated Vessel Primary Motion were failing to run on Windows 95. The program was reporting the error message Could not find the routine "InterlockedExchangeAdd" in the library "kernel32.dll".

New in Version 8.3a (released July 2003)

Simulations

The Extend Simulation menu item now sets winch and vessel stage data for the new stage to be exactly the same as for the previous stage. A vessel using prescribed motion will therefore now continue any acceleration or turning that it was doing at the end of the previous simulation (in OrcaFlex 8.2 any such acceleration or turning stopped). And a winch that paid out a given length in the previous stage will pay out the same length again in the new stage (in OrcaFlex 8.2 the payout stopped).
The dynamic ramping function which is applied during the build-up stage has been changed. The new ramping function is intended to reduce transients at the start of simulations.

Lines

The Line Ends Form is now called the All Lines Form. This is because you can now set line data other than just that which applies to line ends.
Line segmentation was previously determined by specifying an absolute number of segments. In this version, as an alternative you can specify segmentation by giving a Target Segment Length. If you specify segmentation this way then when you alter section lengths the segmentation is not affected.
Clumps can now be aligned with either global axes or line axes.
You can now choose to draw nodes as discs of the same diameter as the line outer diameter.
The Line structure data now has columns which report the cumulative length and cumulative number of segments counted from the first section. The values are for reporting purposes only and cannot be edited.
Line clearance results reporting has been extended. Previous versions of OrcaFlex reported a variable called Line Clearance which reported clearances between centrelines. This results variable did not allow for line outer diameters. We have renamed this variable Line Centreline Clearance and introduced a new results variable called Line Contact Clearance which does allow for line outer diameters. In addition previous versions of OrcaFlex were limited to reporting clearances from a specified line to all other lines in the model. This option is still available but now you can choose to report clearances between 2 specified lines.
An expansion factor data item has been added which allows you to model time-varying changes in unstretched length, for example due to thermal expansion or contraction. The expansion factor used in a simulation is available as a results variable.
A Seabed Reaction Force results variable has been added.
In previous versions of OrcaFlex the local line orientations of lines without torsion were not defined if End A was free or if it was released. This restriction has been lifted in this version but care must be exercised when interpreting any results based on such local line orientations.
The presentation on the line data form of line statics methods has been altered. The data item that was previously labelled Statics Method has been renamed Step 1 Statics Method. The data item that was previously labelled Full Statics has been renamed Step 2 Statics Method.
A new Step 1 Statics Method called User Specified has been added.

Environment

Water density and current speed can now vary with horizontal position in the fluid.
Negative current factors for both vertical variation and horizontal variation can now be used. This allows you to model reversing currents.
The program now allows more flexibility when specifying JONSWAP spectral parameters. There is a new option which allows you to specify directly the 5 principal parameters of the spectrum (Gamma, Alpha, Sigma1, Sigma2 and fm). When using this option Hs and Tz are calculated and reported by the program.
A new wave type called User Specified Components has been added. This allows you to specify the wave train as the sum of a number of sinusoidal components. This wave type gives you complete control over the wave train and would typically be used to compare OrcaFlex results with results produced by a different program.
Wind time history files can now specify variation of both speed and direction. Previously only variation of wind speed could be modelled.
Wind direction is now available as a results variable.
A new button labelled View Vertical Profile 3D View has been added to the Current tab of the Environment data form. This is intended to help you visualise and check your current profile rotation data.
The wave components report and the wind components report now report phases as lags with respect to wave train time and wind time respectively. Previously they were reported with respect to simulation time.

6D Buoys

There is now an alternative way of modelling the linear wave effects on a spar buoy in OrcaFlex. They can now be modelled by specifying force and moment RAOs and added mass and damping matrices.
Multiple applied loads can now act on a 6D Buoy. In previous versions of OrcaFlex you could only specify a single applied load with respect to global axes and a single applied load with respect to local axes.
Applied loads can now vary with simulation time or be given by an external function. In previous versions of OrcaFlex they were fixed throughout a simulation.
Wing orientation angles can now be given by an external function. This is in addition to the existing options of either being fixed or varying with simulation time.
In previous versions of OrcaFlex Wings were drawn using the 6D Buoy pen. There is a new data item in the Wing Type data which allows you to optionally draw the wing using a pen specified in the Wing Type data.
Results for Wings are now output on the 6D Buoy results tables.

Vessels

Multiple applied loads can now act on a Vessel. In previous versions of OrcaFlex you could only specify a single applied load with respect to global axes and a single applied load with respect to local axes.
Applied loads can now vary with simulation time or be given by an external function. In previous versions of OrcaFlex they were fixed throughout a simulation.
The Vessel Type data items current load origin, wind load origin, mass, moments of inertia and centre of gravity can now differ for different draughts of the same Vessel Type. In previous versions you could only specify values for the entire vessel type.
Wave Drift Force and Wave Drift Moment are now available as results variables.
The Report RAOs facility has been significantly extended and renamed as Report Vessel Response. It now includes reporting RAOs for Z Above Wave and it provides a report of spectral values based on the vessel's RAOs. These facilities were previously only available in the separate DOS program OrcaMotion, which is now not needed and so is no longer distributed with OrcaFlex.

Winches

In previous versions of OrcaFlex winches were controlled stage by stage. In this new version the control variable (either target tension or payout rate) can vary with simulation time or be given by an external function. This new form of control is in addition to the existing stage by stage control.
Some new stage by stage winch control modes have been added. These are Specified Payout Rate, Specified Tension Change and Specified Tension Rate of Change. The Specified Payout Rate merely provides an alternative to the existing Specified Payout mode. The Specified Tension Change and Specified Tension Rate of Change modes are more interesting because they allow you, for example, to model a constant tension winch where the tension is determined by an earlier simulation stage. By specifying a tension change of 0 following a payout stage you can lock the winch at the tension used at the end of the payout operation.
Position time history results are now available for each winch connection point. Previously the results were only available for the first connection point.

Links

Position time history results are now available.

VIV Toolbox

There is a new experimental vortex tracking model available, called Vortex Tracking (2).
The Vortex Tracking (1) model now runs about twice as fast as in OrcaFlex 8.2.
With the time domain VIV models you can now disable VIV modelling for specified sections of the line.
OrcaFlex now uses a filter to separate the VIV and non-VIV motion of a node. This allows the wake oscillator models to now handle cases where VIV excitation is due to non-VIV line motion (e.g. due to towing) as well as fluid flow.
The inline and transverse components of vortex force are now available as results. Also, all the vortex force results are now reported per unit length of line (previously the value reported was the force on that node).
You can now specify vortex force factors that allow you to scale the inline and transverse components of the vortex force. These data can be used, for example, to allow for VIV suppression devices or to model the increase in inline drag force due to VIV.
There is now detailed control of how VIV is drawn with the time domain VIV models.
OrcaFlex no longer uses a cut-off angle, i.e. a fluid incidence angle below which VIV is suppressed. This feature of previous releases has been removed since when the incidence angle passed the cut-off angle it caused the vortex force to change, in a single time step, between the force given by the VIV model and the standard drag force. Such step changes in force are unrealistic. Also, all the VIV models are based on the normal component of velocity, which automatically reduces as the incidence angle reduces. If you want you can disable VIV modelling on a section where the incidence angle is low.
OrcaFlex now applies an initial perturbation to the time domain VIV models to initiate oscillation of the wake. With the wake oscillator models it is therefore no longer necessary to apply separate excitation (e.g. using a winch), as was recommended in previous releases of OrcaFlex.
When using the time domain VIV models, OrcaFlex now uses ramping during the build-up stage, to give a smooth handover from the standard Morison drag force, applied in the static analysis, to the vortex force given by the time domain model.

Batch processing

A number of new commands have been added to the batch script language. These are NewModel, Create, Delete, LoadData, SaveData, Reset and ExtendSimulation. The existing Load and Save commands previously loaded or saved data files. They have been altered so that they can now load or save simulation files. The NewModel, Create, Delete commands now allow you to build a model entirely within batch script. The extended Load and Save commands now allow you to automate the modification of post-processing data items (eg. Stress Diameters, Allowable Stress etc.).
You can now set, from batch script, a number of data items that previously could not be set. These included drawing data, variable data source data, QTF data.
Some new command line parameters are available which allow you to instruct OrcaFlex to start a batch calculation as soon as the program has loaded.

Interface and Results

The model browser has a new facility called the By Groups View which allows you to define a tree structure associated with your model. This is particularly useful for navigating large models. Closely related objects can be grouped together and folders of objects which you are not currently working on can be closed and thus hidden from view in the browser. The traditional By Types View which groups together objects of the same type is still available.
More than one object can be selected in the model browser. This allows you to perform the same action (eg. delete, copy, hide, show, locate) on many objects at once. To select more than one object you use the standard Windows key presses CTRL+CLICK to add to a selection and SHIFT+CLICK to extend a selection.
Popup hints are now shown when you hover the mouse over an object in the 3D View. These hints can be disabled by setting a preference.
Statics accuracies are now reported in the Properties Report for 3D Buoys, 6D Buoys, Vessels and Lines.
A new Locate Object Method preference has been added. It determines what method the Locate action in the model browser uses.
Files can be added to the batch processing form by drag and drop.
Multiple File Replays now allow you to set the view parameters for each frame of the replay. This allows you to zoom, pan and rotate the view during the replay.
There is a new Graph menu on the OrcaFlex main menu. This gives access to various functions that were previously only available through the popup menu.
A new period called Instantaneous Value is available for range graphs. Graphs with this period do not show a curve of the values at the instantaneous simulation time. This is normally the latest simulated time. However, if a replay is active, the graph shows a curve of values at the replay time. This allows you to see, for an entire line, how a results variable evolves over a simulation.
OrcaFlex can now produce Rainflow half-cycle Empirical Cumulative Distribution graphs.
There is a new Delete Unused Variable Data Sources facility on the Model menu.
Range Jump Suppression is now applied for range graphs of angle results. Previously it was only applied for Time History and XY Graphs.
A Use Default Tick Spacing button has been added to the Graph Properties form.
The Undo Zoom item on the Graph popup menu has been renamed Use Default Ranges.

Post-processing

The Linked Statistics command in the Results spreadsheet is now available for a single results variable.
The Results Spreadsheet can now be used with a statics only OrcaFlex licence. The Load command now allows you to load a data file. After the data file has been loaded the spreadsheet performs the OrcaFlex statics analysis. This may be time consuming so we recommend using the Use Calculated Positions feature when building the model. Commands available are Range Graph, Range Graph Summary and the new command Static Result which is like the Time History command but just gives a single value.
The Results Spreadsheet can now output data values.
The Results Spreadsheet can now output pipe stress component results. This was not possible in previous versions because there was no way to specify R,Theta in the results spreadsheet. This is now possible using the new Additional Data column on the results spreadsheet. Because of this we are no longer supplying the Stress Spreadsheet which was supplied with older versions of OrcaFlex. Old Stress Spreadsheets will continue to work but we now recommend you use the Results Spreadsheet for post-processing pipe stress component results.
The Results Spreadsheet can now output results for Wings by specifying the wing name in the new Additional Data column on the results spreadsheet.
The Results Spreadsheet can now output results for the Environment by specifying the position of the point for which you want results in the new Additional Data column on the results spreadsheet.

OrcaFlex Programming Interface

New functions C_ClearModel, C_GetDefaultUseCalculatedPositionsForStaticsParameters, C_GetModelState, C_GetObjectType, C_GetObjectTypeName, C_GetRangeGraph3, C_GetRecommendedTimeSteps function, C_UseCalculatedPositionsForStatics, OrcinaInfinity and OrcinaUndefinedReal have been added to the OrcaFlex Programming Interface.

Bug fixes

Shape results tables were sometimes reporting the wrong contact force. The error only occurred for results tables of the static configuration and for contact with lines which included torsion. The error was that the contact forces due to lines which included torsion were counted double. Note that the values used in the calculations were correct.
Current Speed results previously did not allow for the build-up ramp if the current was ramped during build-up. Note that the value used for calculation purposes correctly allowed for the ramp. The error only affected the reported values of the Current Speed results variable.
OrcaFlex was sometimes failing to locate time history files when opening simulations. This occurred for models which used using time history files with relative paths.
The Time History Import Wizard was failing to locate time history files which used relative paths.