Orcina news

Continuing our series of posts on upcoming developments for version 10.2, we consider a number of enhancements to the line clearance results.

Historically, OrcaFlex has offered results reporting the clearance between lines. These results report the shortest distance, in 3D space, between lines. Results are available for clearance between centrelines or between contact surfaces. Some OrcaFlex applications, for example riser / pipeline crossing analysis, call for clearance distances measured horizontally or vertically. A number of new results variables have been introduced in 10.2 to address these requirements.

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Continuing our series of posts on upcoming developments for version 10.2, we consider a couple of enhancements to the support and constraint objects.

OrcaFlex objects can be connected to each other, so that the connected objects move together. In addition, certain types of connections can be released at defined points in the simulation. For example, line, link and winch connections can all be configured to release at the beginning of a specified stage in the simulation. Version 10.2 introduces the same capability for supports and constraints.

Continue reading “Upcoming in OrcaFlex 10.2: Support and constraint release”

Continuing our series of posts on upcoming developments for version 10.2, let’s now look at a further relaxation of the rules relating to object connectivity.

In version 10.0 we made it possible to connect lines to lines and to form chains of connections, e.g. 6D buoy1 is connected to 6D buoy2, which in turn is connected to 6D buoy3 etc. In version 10.1 the constraint object was introduced, and mid-line connections were enabled.

In version 10.2 it will be possible to connect both vessels and 3D buoy objects as slaves of other objects.

Continue reading “Upcoming in OrcaFlex 10.2: Vessels and 3D buoys can be slave objects”

Continuing our series of posts on upcoming developments for version 10.2, we now move to an important enhancement to modal analysis. This development has aspects in common with another new feature, line statics policy, which we have discussed in an earlier post.

OrcaFlex modal analysis calculates modes for individual lines or for the entire system. The individual line option is commonly used to generate mode shapes for use in an external VIV analysis program like SHEAR7 or VIVA. Modal analysis for an individual line is based on the assumption that the line end nodes are fixed, and the remaining nodes in the line have freedom. For many riser or umbilical configurations it is perfectly reasonable to use these modes in a VIV analysis. However, there are some systems for which this approach is not appropriate, and the new coupled object modal analysis feature is intended to addresses this limitation.

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We have somewhat neglected our series of posts on upcoming developments for version 10.2 of late, mostly because we have been working flat out on some new features. In this post we will cover multi-level undo and redo in the user interface.

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Continuing our series of posts on upcoming developments for version 10.2, we look at some enhancements to static analysis.

Version 10.0 relaxed the rules for connecting objects together, one aspect of which was allowing lines to be connected to other lines. This new flexibility had a number of consequences for static analysis of lines. In version 10.0, these consequences were dealt with in a very simple manner and in many situations that approach worked perfectly adequately. However, some models that took advantage of more general connectivity proved difficult to handle in static analysis. In version 10.2 we have introduced some new functionality to address these issues.

Continue reading “Upcoming in OrcaFlex 10.2: Line statics policy”

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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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.

Continue reading “Upcoming in OrcaFlex 10.2: Documentation”

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.

Continue reading “Upcoming in OrcaFlex 10.2: Vessel calculation mode”

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.