The OrcaFlex Blog

We are very pleased to announce the release of OrcaFlex version 9.2a. We are now starting the process of producing the installation CDs and customers with up to date MUS contracts should receive the upgrade in the middle of September.

There are a great many enhancements to the software which we described in the previous blog post. The only significant change in the software from that post is that the non-linear soil model is not included in 9.2a. We have not had sufficient time to perform the testing and validation of this development to a level sufficient for release. We are continuing to work on this and hope to include the non-linear soil model in a minor 9.2 update sometime later this year.

It’s been a long time since our last article and we’ve all been very consumed with work for OrcaFlex 9.2. We are nearly ready to release this major upgrade and are now in a position to announce the new features which it will introduce. The major enhancements fall into the following categories:

• Performance
• Bend Stiffener and Stress Joint modelling
• Multi-threaded batch processing
• Fatigue post-processing enhancements
• Non-linear seabed
• Wake deficit / interference modelling
• Wave spreading
• 6 DOF Vessel QTFs
• Python interface to OrcFxAPI

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We have just released a minor upgrade to OrcaFlex, version 9.1c. We strongly recommend that all users of 9.1 upgrade to 9.1c.

Version 9.1c fixes two bugs as described below:

Vessels

Versions of 9.1a and 9.1b had a bug which affected vessel motions and runtime performance when all of the following conditions were met:

• The implicit integration scheme was in use.
• A vessel had Primary Motion set to “Prescribed” or “Time History”.
• That same vessel had Superimposed Motion of “None”.

When all these conditions were met then vessel motions contained errors. The errors build up gradually during the simulation which means that longer simulations are more seriously affected. In addition simulations were significantly slower than they should have been.

In version 9.1c the problem has been corrected.

Lines

Versions 9.1a and 9.1b had a bug related to the new hint window results feature introduced in version 9.1a. If a replay is paused and you hover the mouse pointer over a line then a hint window is displayed. This hint window now includes results. The code to derive these results contained a bug which corrupts Summary and Full Results for the line, and also corrupts the 3D View of the latest simulation position.

Note that the bug does not affect other results such as Time History, Statistics, Range Graph etc. It also does not affect replays. The bug is corrected in version 9.1c.

Obtaining the upgrade

A patch to upgrade from any earlier version of 9.1 to 9.1c is available for download from our website. When downloading the patch you will be asked for a username and password which you can find in the OrcaFlex 9.1 About box (see About on the Help menu).

If you would prefer to receive version 9.1c on CD please contact us.

As I’m quite sure every OrcaFlex user knows by now, OrcaFlex 9.0 introduced an implicit time domain solver in addition to the existing explicit solver. This change led to huge improvements in run times and thus prompted us to award the release ‘major upgrade status’ and promote it from version 8 to version 9!

In August 2007 we released OrcaFlex 9.1, which introduced many further improvements to the implicit solver — version 9.1 is now significantly faster than 9.0. The purpose of this blog post is to discuss some of the improvements in version 9.1, present a runtime comparison with Flexcom, and to discuss some future developments we plan to make OrcaFlex even faster still.

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One of the changes we made in OrcaFlex 9.1 was a re-mapping of keyboard shortcuts. Mostly this was motivated by a desire to map CTRL+S to File | Save and CTRL+O to File | Open.

To make room for these changes we had to rearrange a number of other shortcuts. In particular the shortcuts to rotate the 3D View were changed to CTRL+ALT+ ← → ↑ ↓. Shortly after releasing version 9.1 we began to hear reports from some users that their laptop screen would suddenly be displayed upside down, or on its side, after using one of these shortcuts.

After a little detective work we have traced the issue to a piece of Intel software that is stealing these keyboard shortcuts before they reach OrcaFlex. The solution is as follows:

1. Open the Control Panel and make sure it uses Classic View.
2. Double click the Intel GMA Driver for mobile icon.
3. Select the Hot Keys page.
4. Deselect the “Enable Hot Keys” option.

This will fix the problem for Intel graphics cards, but there may be similar problems for cards from other manufacturers, or even for different Intel cards. I’m guessing that similar solutions will be available and that the steps described above should help you solve such problems.

This article proposes some possible changes that we are considering, to the way OrcaFlex treats the water inside a hollow spar buoy, i.e. where a spar buoy object in an OrcaFlex model has a non-zero ID specified for one or more of its cylinders. We would welcome feedback from OrcaFlex users (and potential users) on whether the change that we are considering would be a useful.

The existing OrcaFlex treatment of hollow spar buoys is aimed at modelling hollow axi-symmetric structures that flood and drain very freely in the axial direction. But it is less suitable for hollow objects that do not flood and drain so easily, and these proposals aim to address this.

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Many of the software support questions we receive concern statics convergence. Before the release of OrcaFlex 9.0 we would regularly employ a host of methods to deal with stubborn cases. The problem cases would usually involve 6D Buoys.

OrcaFlex 9.0 introduced a new statics method called Whole System Statics (WSS) which provides a great leap forward in terms of robustness and speed of convergence. Practically all support queries relating to statics convergence are now solved by switching to use WSS. So what makes WSS so much better than the old method?

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Orcina have recently carried out a validation of the way OrcaFlex handles buoyancy forces and pipe internal contents pressure effects, and the resulting effective tension and wall tension that OrcaFlex reports. We have validated these OrcaFlex results against results presented in Nigel Barltrop’s well-respected book “Dynamics of Floating Structures: a guide for design and analysis. Volume 2″. The OrcaFlex results matched the Barltrop results very well, confirming that OrcaFlex models buoyancy and internal pressure effects correctly.

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Welcome to our new OrcaFlex Blog!

We’ve been contemplating writing a blog for some time now and have finally decided to take the plunge. The idea is to try to encourage the development of the OrcaFlex community. Our annual User Group Meetings are a big part of this, but a blog can be more immediate and interactive. There are hundreds of active OrcaFlex users in the world and we hope that this blog will help bring them closer together.

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