Orcina news

Here you will find the latest news on the development of OrcaFlex. Alongside our LinkedIn page, it is a valuable source of information about what we are up to!

Upcoming in OrcaFlex 10.2: Compound properties report

Continuing our series of posts on upcoming developments for version 10.2, we will take a look at a relatively simple, yet frequently requested enhancement to model building.

Complex structures are often modelled in OrcaFlex using multiple objects that are connected together. A common example would be a manifold modelled using a combination of lumped buoys and single segment lines, all connected together so as to move as one rigid object. When building such a model, there is plenty of scope for error. For instance, it is easy to forget to account for some part of the structure, or equally to double count parts of the structure. A common way to detect such mistakes is to calculate the combined mass, volume, centre of mass, centre of volume, etc. and compare with known values.

Previously, OrcaFlex did not offer any functionality to calculate these compound properties, but version 10.2 will address that.

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Distributed OrcaFlex 6.0a released

We have just released Distributed OrcaFlex 6.0a which you can download from the Distributed OrcaFlex web page.

The significant change introduced in this release is the ability to run more than one Distributed OrcaFlex (DOF) Client process on the same computer. The motivation for the change is to support machines with very large numbers of processors. Machines with more than 64 processors have the processors split into processor groups. Each DOF Client can only use processors from a single group. For previous versions, there was a single DOF Client process per machine and so that process could only use processors from a single group. Allowing multiple DOF Client processes on a single machine enables full use of the processing capacity of that machine.

As well as the issue of processor groups, machines with large numbers of processors usually use NUMA memory architecture. In order to make the best use of such machines, programs need to make sure that memory is allocated on the NUMA node which contains the processors that use that memory.

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Upcoming in OrcaFlex 10.2: Documentation

Continuing our series of posts on upcoming developments for version 10.2, we will now turn to some functionality entirely outside of the program, namely the documentation. OrcaFlex is an ever growing program, and as it grows, so too does the documentation. For version 10.2, we decided to make a number of significant changes to the documentation, especially in how mathematical formulae are presented.

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Upcoming in OrcaFlex 10.2: Vessel calculation mode

As mentioned in a recent post here, we are going to publish a series of articles introducing some of the new features being developed for release in version 10.2. This article is the first of that series, discussing a new vessel option that allows users to make a choice between two methods for the interpretation of diffraction analysis data.

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Mooring Chain Bending Fatigue (following Bureau Veritas Guidance Note NI 604 DT R00 E)

Mooring line fatigue damage normally considers only tension load cycles. However, sometimes the mooring chain immediately adjacent to the fairlead (the ‘Top Chain’) can experience significant in-plane and out-of-plane bending which causes additional fatigue damage.

BV guidance note Fatigue of Top Chain of Mooring Lines due to In-plane and Out-of-plane Bendings, [NI 604 DT R00 E, Aug-14], (‘BV note’) describes a Top Chain fatigue damage assessment procedure which includes both tension and bending. Here we describe how to derive the necessary OrcaFlex results to use with the procedure outlined in the BV note.

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OrcaFlex Development plans for 10.2 and beyond

In the past we have not been very expansive about our development plans for OrcaFlex – usually nothing more than a short bullet list on our website. We’d like to engage more with our users about upcoming OrcaFlex developments. This post is intended to kick-start us in that direction.

But before we get into the details, here are some points that might be useful background:

  • For roughly the last 10 years OrcaFlex has been released annually, usually around September or October.
  • The latest release of OrcaFlex is 10.1c. Version 10.1a was released in October 2016.
  • The version number denotes the major release – 10.1 is the current major release, 10.2 will be the next major release.
  • Each version number has a minor revision letter with a marking the first minor revision, b indicating the second minor revision, etc.
  • Minor revisions are intended to fix bugs rather than introduce major new functionality.
  • Our website details OrcaFlex releases since version 9.5 in 2011.
  • We also occasionally remove functionality – usually when we believe this is not being used.

In terms of individual functionality changes (both additions and removals), our software team plan to blog more about these on other occasions. This post summarises our planning process and states where we are currently with our plans for version 10.2 and beyond.

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Less Common Applications for OrcaFlex

OrcaFlex is primarily used in the offshore oil and gas industry, typically for installation analysis and in-place design of riser and mooring systems, pipelay analysis, field construction, etc., as well as being widely used in the oceanographic community. However, OrcaFlex is an extremely versatile package, and over the years we have seen it used for the global dynamic analysis of a wide variety of applications. Starting what will be an occasional series of blog postings about less common applications for OrcaFlex, we kick-off with a summary of these.

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Bugs in Python 2.7.11 and 2.7.13 that directly affect OrcaFlex

OrcaFlex has a number of features that take advantage of the Python programming language. We work hard to ensure that OrcaFlex is compatible with a wide range of Python versions. However, a couple of recent Python releases have contained bugs that have broken functionality that OrcaFlex relied upon.

  • Python version 2.7.11 is affected by issue 26108. This did not affect automation of OrcaFlex from a Python process. The defect meant that when Python was embedded in an OrcaFlex process, for external functions or post-calculation actions, OrcaFlex would crash when it attempted to load the embedded Python modules. We were able to workaround this particular defect and OrcaFlex 10.0e and later do so.
  • Python version 2.7.13 is affected by issue 29082. This issue has no impact on embedding Python in OrcaFlex, but instead breaks the import of the OrcFxAPI module from a Python process. At the moment we have no workaround for this defect.

Because of these problems we recommend that you do not install either of these versions of Python. If you must use a version from the 2.7 family then we would recommend 2.7.12.

Update: Since this post was originally written, version 2.7.14 has been released which addresses both of these problems.

Python 2 is now maintained only to add bug fixes, and mainstream development attention for Python is given to Python 3. The problems that we have encountered with 2.7, as described above, lead us to recommend that an up-to-date Python 3 should be used with OrcaFlex if at all possible.

Python 3.6 has very recently been released and the next minor update to OrcaFlex, version 10.1c, will support this.