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!

Incompatibility between OrcaFlex 10.2 or 10.3 and Anaconda Python 3.7

Some OrcaFlex users have reported program crashes when trying to execute embedded Python code. These crashes causes OrcaFlex to close without reporting any error message.

If Python scripts are used for OrcaFlex post calculation actions, user defined results or external functions, OrcaFlex must launch a Python interpreter to run the input scripts. We refer to this mode of operation as running embedded Python.

Some clients make use of Anaconda products as their installed Python. However, Anaconda’s packaging of Python 3.7 fails to initialise when OrcaFlex wants to run some embedded Python code, leading to a program crash.

This issue can usually be resolved by creating a new environment variable, PYTHONHOME, and setting its value to your Anaconda Python installation directory.

You can find the environment variables by starting with the System Properties window:

Windows System Properties

and add PYTHONHOME by selecting New… from the User Environment Variables list:

Windows Environment Variables
New PYTHONHOME environment variable

OrcaFlex version 11.0 provides the Python home directory information to embedded Python automatically. Updating OrcaFlex to version 11.0 will therefore resolve the issue without requiring you to modify environment variables.

We would like to thank all of our users who brought the problem to our attention, and also helped us to find the solution!

OrcaFlex 11.0 released

We are very pleased to announce the release of OrcaFlex version 11.0. The software was finalised and built on 28th November. All clients with up-to-date MUS contracts should receive, by e-mail, instructions on how to download the new version.

Version 11.0 introduces much new functionality, including:

  • Diffraction analysis
  • Enhanced wind turbine modelling
  • Wind drag loading for 6D buoys
  • Enhanced wind specification
  • Disturbed sea state results for vessels
  • New results variables
  • Hysteretic constraint stiffness
  • Enhancements for 3D views
  • Software licensing

These are the most significant developments, in our opinion. As always there are more enhancements that are not listed here. All new features are fully documented in the what’s new topic for 11.0.

Continue reading “OrcaFlex 11.0 released”

OrcaFlex turbine controller examples

OrcaFlex 10.3 introduced the turbine object, used to model horizontal axis wind turbines.

A key issue for wind turbine analysis is the modelling of the generator and blade control systems. Because these control systems are typically proprietary, OrcaFlex does not offer any built-in control system functionality. Rather, the user must specify the control systems through external functions.

When we released 10.3d, we updated the documentation to include some example external function controllers. The pertinent help topics are:

These documentation topics contain links to the controller examples which can also be downloaded directly.

Other useful sources of information for turbine modelling:

OrcaFlex 10.3 turbine validation

Following the introduction of the turbine model object in version 10.3 we have now produced a report which details the validation performed on the turbine against documented industry studies.

The validation study considers the National Renewable Energy Laboratory (NREL) offshore 5-MW baseline wind turbine, which is
recognised as an industry-standard reference turbine system.

Two separate turbine systems have been modelled and subjected to detailed analysis in OrcaFlex:

  • A land-based wind turbine system.
  • A floating wind turbine system – based on the OC3 Hywind system.

Analysis of the land-based scenario was considered to facilitate basic validation of the turbine response determined via OrcaFlex. Detailed analysis of the OC3 Hywind system was then considered to help validate the behaviour of a fully-coupled floating wind turbine system in OrcaFlex.

 

The OC3 Hywind system modelled in OrcaFlex 10.3
The OC3 Hywind system modelled in OrcaFlex 10.3

Results were compared to those from other wind turbine simulation tools; namely FAST, MSC.ADAMS, Bladed and HAWC2.

Overall, OrcaFlex has been shown to accurately capture the aerodynamic and hydrodynamic loading on the considered turbine systems. Close agreement was generally observed between the OrcaFlex results and those available from the other simulation tools – particularly with respect to the calculated turbine rotor response.

The full report is available alongside previously published OrcaFlex validation cases on the validation page here.

OrcaFlex 10.3c released

We have just released a minor upgrade, version 10.3c, which fixes a number of bugs. Full details of the changes are described here. We recommend that users of 10.3 upgrade to 10.3c.

A patch to upgrade from 10.3a or 10.3b to 10.3c can be downloaded here. The full installation program can also be downloaded from your download page. Please contact us if you do not have the link to your download page.

OrcaFlex 10.3b released

We have just released a minor upgrade to OrcaFlex, version 10.3b. Version 10.3b introduces some minor new functionality and fixes a number of bugs. Full details of the changes are described here.

A patch to upgrade from 10.3a to 10.3b can be downloaded here. The full installation program can also be downloaded from your download page. Please contact us if you do not have the link to your download page.

OrcaFlex 10.2d released

Coinciding with the release of version 10.3, we have just released a minor upgrade to OrcaFlex 10.2, version 10.2d. This 10.2 update addresses all outstanding known bugs on the 10.2 branch.

A patch to upgrade from earlier releases of 10.2 is available. Alternatively, the download page for 10.3 (sent by e-mail to your company software administration contact) offers downloads of full installation programs for older versions.

OrcaFlex 10.3 released

Once again, it’s that time of year at Orcina where we release a brand new version of OrcaFlex and so we are very pleased to announce the release of version 10.3. The software was finalised and built on 28th November.

A particular novelty this year is that we are now distributing the software electronically. Finally we have moved in to the 21st Century and will no longer be sending you CDs in the post! All clients with up-to-date MUS contracts should receive by e-mail instructions on how to download the new version.

Version 10.3 introduces much new functionality, including:

  • A new turbine object designed for modelling of floating wind turbines. This is a composite object with dedicated models for the generator, gearbox, hub and blades.
  • Quasi-dynamic mooring analysis is now possible through the addition of a comprehensive analytic catenary solver.
  • User defined results which allow you to extend OrcaFlex by defining, using Python scripts, additional results.
  • Object tags, a set of user defined name/value pairs associated with objects in an OrcaFlex model. Tags are intended for use by external functions, post calculation actions, user defined results, post-processing scripts etc.
  • Line pre-bend data can now be visualised at the point of data input, and can be specified in a more convenient format than in previous versions.
  • Friction can now be included in the line support contact model.

These are the most significant developments, in our opinion. As always there are more enhancements which are fully documented in the What’s New topic for 10.3.

Continue reading “OrcaFlex 10.3 released”

Using curvilinear constraints to impose motion

OrcaFlex has two objects whose motion can be imposed rather than calculated:

  • The vessel object through displacement RAOs, harmonic motion, time history or externally calculated motion.
  • The constraint object (added in version 10.1) through motion time histories in the constraint’s imposed displacement mode.

In addition to these more well-known methods of imposing motion, the constraint object has another mechanism that allows motion to be imposed.

Continue reading “Using curvilinear constraints to impose motion”