The OrcaFlex Blog

We are very pleased to announce the 2011 major release of OrcaFlex, version 9.5. As always it takes time to produce and despatch installation CDs but clients with up-to-date MUS contracts can expect to receive the software in the first half of November.

The major enhancements introduced in 9.5 are as follows:

• Slam loads.
• Wave drift damping and manoeuvring loads for vessels.
• P-y models to model lateral seabed reactions for vertical lines.
• Equivalent line modelling.
• Support for SHEAR7 version 4.6.
• Improved automation capabilities.
• Replays can track and follow the movement of objects.
• Docked model browser.
• External functions: now available with the implicit solver and can be written in Python.

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We have just released a minor upgrade to OrcaFlex, version 9.4d.  The most significant changes introduced with 9.4d are:

• Rainflow fatigue analysis would, under certain situations, fail and report an out of memory error.  Version 9.4d addresses this issue and we believe that this error will no longer occur.
• A number of bugs related to end load results reporting for bend stiffener objects have been fixed.

Many other less significant bugs have been fixed.  Full details of the enhancements and bug fixes in 9.4d are described on our website.

We would recommend all users of 9.4b to upgrade to 9.4d.  A patch to upgrade from 9.4b to 9.4d is available.  If you would prefer to receive version 9.4d on CD please contact us.

A whole year has now passed since we released OrcaFlex 9.3 which means that it is time for the release of OrcaFlex 9.4! As always it takes time to produce and despatch installation CDs but clients with up-to-date MUS contracts can expect to receive the software some time around the end of August.

The major enhancements in version 9.4 fall into the following categories:

• Improved performance of the OrcaFlex post-processing spreadsheet.
• Enhancements to modal analysis: whole system analysis, better performance.
• Enhancements to fatigue analysis: mean stress, mooring fatigue using T-N curves, SHEAR7 fatigue.
• Line contents modelling: free-flooding, slug flow, spatial and temporal variation of contents.
• Vessel data import enhancements for generic text files.
• Better handling of vessel RAO data which omits zero period response.
• Improved modelling of solid contact at edges and corners.
• Line floats wizard now supports Reynolds number dependent drag.

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As now seems to be traditional, here at Orcina we have spent the summer months working very hard to complete a major upgrade to OrcaFlex. The result is OrcaFlex 9.3 which was formally released early in August. We have just despatched the final upgrade CD and so all customers with up-to-date MUS contracts will have the software very soon, if not already.

I should also point out that we have released a minor upgrade (version 9.3b) which fixes some bugs that have come to light in version 9.3a (the version included on the upgrade CD). As usual a patch to upgrade from 9.3a to 9.3b is available for download.

The major enhancements in version 9.3 fall into the following categories:

• Extreme value statistics post-processing of results variables.
• Text data file (in addition to existing binary data file).
• Enhanced interface to SHEAR7.
• Static state simulation files.
• Non-linear material properties for elastomeric bend stiffeners.
• API 2RD stress check.
• Coatings and linings for homogeneous pipe.
• Roll damping for vessels.
• Modal analysis improvements.
• Performance improvements.

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We have recently become aware that the version of the OrcaFlex spreadsheet released with OrcaFlex 9.2 has some performance problems. These do not always manifest themselves and we have not seen the problems ourselves. Fortunately a small number of clients have raised the issue and we have been able, with help from those clients, to diagnose the problem. We have released an updated version of the OrcaFlex post-processing spreadsheet which corrects the fault. If you are suffering from slower than usual results extraction in the spreadsheet then you are probably experiencing this problem.

While we are on the subject of the post-processing spreadsheet it seems appropriate to announce some of the changes we are making for 9.3. As you are probably aware the post-processing spreadsheet is implemented using Excel VBA macros. These link, in turn, to the OrcaFlex code through our OrcFxAPI DLL.

VBA macros have many strengths but we have become somewhat constrained by their limitations. For 9.3 we will be moving all the code into the OrcFxAPI DLL. One immediate benefit of this is that our spreadsheet template will no longer contain any macros and so will not be subject to Excel’s macro security dialogs.

For 9.3 we are planning to keep the user-interface to the spreadsheet identical to previous versions. We are, however, planning one very significant change to the implementation. All previous versions processed instructions serially and made no use of the multi-core processors that are now commonplace. It is not possible to perform calculations in parallel with VBA macros. Moving the processing code into the OrcFxAPI DLL will enable us to process load case results extractions in parallel. This should significantly reduce the time taken to post-process results.

This development is currently partially complete and we have not yet implemented the multi-threading of the results extraction. I look forward to being able to write about the performance of the multi-threading aspect of this work when it is complete. Hopefully I’ll be able to announce big improvements in extraction times.

We have now released the non-linear seabed soil model in OrcaFlex 9.2e (see the OrcaFlex 9.2 Support section of our website). The model has been developed by Professor Mark Randolph (Centre for Offshore Foundation Systems, University of Western Australia), a recognised expert in this field, and we have been working with Mark to implement the model in OrcaFlex.

The model is for modelling the seabed resistance for catenary pipeline contact. It takes as input the line diameter and the seabed soil geotechnical properties (undrained shear strength at the mudline, shear strength gradient with depth, soil saturated density). It then calculates the seabed reaction force on each line element as a function of the penetration, allowing for non-linear penetration resistance, hysteretic effects due to uplift and repenetration, and non-linear suction forces.

Some of the model characteristics are illustrated in the following diagram. For comparison, the standard OrcaFlex linear seabed model would give just a straight line seabed reaction curve in the diagram.