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!

New floating photovoltaic array example

A new example, K06 FPV array, is now available on our website. This example demonstrates one method of modelling a floating photovoltaic (FPV) array system in OrcaFlex and can be found in the K Renewables section of the OrcaFlex examples webpage.

The array is made up multiple modular rafts which are connected using indirect constraints with double-sided connections. The array model was built by duplicating a template model which represents a single raft module. The model building process was automated using the OrcaFlex programming interface (OrcFxAPI) and this is demonstrated in the Python script supplied alongside this example.

The accompanying PDF document goes into further detail on the model building process, setting data and interpreting results. It also includes a discussion on indeterminate systems and how they can sometimes arise.

We hope that this example is informative and can provide some useful insights into both new and existing OrcaFlex features that can help model floating array systems.

OrcaFlex model of a floating array with 64 rectangular rafts in the array and 12 buoys in the mooring system.
OrcaFlex model of a floating photovoltaic (FPV) array.

IEA 22 MW RWT validation study

We have recently put together a validation study which compares the aeroelastic response of the IEA 22 MW reference wind turbine (RWT) calculated by OrcaFlex, versus OpenFAST (running BeamDyn).

A report summarising a full comparison of results can be downloaded from the validation page of the Orcina website. The study considers the structural dynamics of the turbine blade oscillating freely under gravity and the aeroelastic response of the rotor-nacelle assembly (RNA) & tower to steady, stepped, skewed & turbulent wind.

Included with the report is the OrcaFlex model we have used to support the validation study. The model includes the rotor, nacelle and tower only i.e. no fixed / floating foundation has been considered as part of this study. The data used as input to this model have been gathered from version 1.0.1 of the the windIO dataset, made available through the IEA-22-280-RWT GitHub repository. The windIO ontology contains the majority of data required to specify an OrcaFlex turbine model. Any absent data have been sourced from the available OpenFAST and HAWC2 datasets. Further details about this can be found in Section 2.1 of the validation report.

Also included with the model is version 2.9.0 of NREL’s Reference Open Source Controller (ROSCO), complete with the necessary input files distributed as part of the ‘IEA-22-280-RWT-Monopile’ dataset.

Overall, we have found the results to be in very close agreement, supporting both the validity of the OrcaFlex RWT model and consistency across the two aeroelastic codes. Included below are some select results from the validation report.

We hope this resource will be helpful to anyone modelling wind turbines in OrcaFlex. We always welcome any questions or feedback, so please do contact us for any further enquiries.

 

OrcaFlex model of the IEA 22 megawatt reference wind turbine
OrcaFlex model of the IEA 22 MW reference wind turbine
Comparison of the aerodynamic and operational steady-state response of the 22 megawatt rotor
Comparison of the aerodynamic and operational steady-state response of the 22 MW rotor
Comparison of the blade and tower response to turbulent wind
Comparison of the blade and tower response to turbulent wind

OrcaFlex 11.4c released

We have just released a minor upgrade to OrcaFlex, version 11.4c. Version 11.4c fixes a number of bugs. Full details of the changes are described in the documentation:

We recommend that all users of 11.4 upgrade to 11.4c.

To upgrade to OrcaFlex 11.4c from any previous version, download the install program from your company’s Orcina software download page. A link to this page was sent to your software administration contact when we released 11.4a. If you do not have access to this page, please contact us.

OrcaFlex 11.4b released

We have just released a minor upgrade to OrcaFlex, version 11.4b. Version 11.4b introduces some minor new functionality and fixes a number of bugs. Full details of the changes are described in the documentation:

We recommend that all users of 11.4 upgrade to 11.4b.

To upgrade to OrcaFlex 11.4b from any previous version, download the install program from your company’s Orcina software download page. A link to this page was sent to your software administration contact when we released 11.4a. If you do not have access to this page, please contact us.

New diffraction example

A new example is now available on our website: L03 Semi-sub multibody analysis. This example focusses on a semi-sub platform that closely resembles the OC4 platform, as modelled in example L02.

In the L02 example, we assume the platform is a single rigid body. In the L03 example, we are interested in the loads acting through the connecting members. Consequently, we have divided the platform into four distinct floating bodies and used OrcaWave to run a multibody diffraction analysis. In OrcaFlex, the four vessel objects are connected via line objects with structural properties that represent the cross bracings and pontoons. Further details can be found in the accompanying PDF description document.

Please note that example L03 takes advantage of recent developments to improve the workflow when defining external stiffness for multibody analyses. Therefore, this example is intended for use with OrcaWave and OrcaFlex version 11.4 onward.

In version 11.4 we also developed OrcaWave and OrcaFlex to be capable of undertaking multibody analyses for objects consisting of multiple sectional bodies. This new feature is not considered as part of this example, although we hope to develop an example that will demonstrate this feature in the future.

We hope that you will find this latest example helpful and informative.

L03 Semi-sub

OrcaFlex 11.4 released

We are very pleased to announce the release of OrcaFlex version 11.4. The software was finalised and built on 22nd November. All clients with up-to-date MUS contracts will receive, in the week starting 27th November, an e-mail with instructions on how to download and install the new version.

Version 11.4 introduces much new functionality, including:

OrcaFlex

OrcaWave

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 topics:

Continue reading “OrcaFlex 11.4 released”

Correction to L02 OC4 semi-sub example

We have recently identified an issue with the L02 OC4 semi-sub example, where incorrect linear damping coefficients were used as input to the semi-submersible model.

To explain the problem, the original damping coefficients were referenced from a comparison study against tank test results, documented as part of the Offshore Code Collaboration study OC6 project – Phase I. The coefficients were then calibrated in OrcaFlex, through a series of free-decay tests. Those tests used damping coefficients with force units of newtons (N), however, the example models uses units of kilonewtons (kN). This difference in units was not accounted for as part of the model building process, which led to the transfer of incorrect coefficients to the ‘Other damping’ page of the OrcaFlex vessel type data form.

In light of this mistake, the supporting OrcaWave and OrcaFlex models have been corrected, and the latest version of the example is now available for download from the usual L Diffraction examples page of the Orcina website. For clarity, the correct coefficients are shown below:

Corrected linear damping coefficients for the L02 OC4 semi-sub example

This serves as an important reminder that the available published Orcina examples are intended for illustrative purposes, meaning they should be checked for accuracy and modified appropriately to suit the individual needs of an application or project.

We apologise to anyone who might have been inconvenienced by this oversight. Should you need any further clarification, then please do contact us for further details.

OrcaFlex 11.4 user group meetings

Following the release of OrcaFlex 11.4, we can now announce our OrcaFlex 11.4 user group meetings. Once again, we are running these as virtual webinars.

These webinars will cover all the new features introduced in version 11.4 of OrcaFlex and OrcaWave. We will split the content into two separate webinars, one for OrcaFlex and one for OrcaWave. Each webinar will be delivered twice in the same day to give users in different time zones the opportunity to attend.

We anticipate that each webinar will be around one hour in duration, and attendees will be able to ask questions. Recordings of the webinars will be available on our website shortly after they have taken place.

We are running the webinars over Zoom. You will need to register, using the links below, for whichever webinars you wish to attend, using the links below. Zoom webinars can be attended using the Zoom client, or directly from the browser if you do not have the Zoom client.

We look forward to catching up with our regular user group attendees, and hopefully some first timers too!

OrcaFlex new features

This webinar will introduce the new features in OrcaFlex.

TimeRegistration
12th December 2023
0900 GMT
https://us02web.zoom.us/webinar/register/WN_0lf6bYAzQ7-uQvrLVIoH9g
12th December 2023
1700 GMT
https://us02web.zoom.us/webinar/register/WN_gHvki719SLy1n9B2RlvpZw

OrcaWave new features

This webinar will introduce the new features in OrcaWave, our diffraction analysis program

TimeRegistration
14th December 2023
0900 GMT
https://us02web.zoom.us/webinar/register/WN_4W5oBsGESKq_076TVsoiDQ
14th December 2023
1700 GMT
https://us02web.zoom.us/webinar/register/WN_FzCOsEgzS7y199e6lnW0SQ

OrcaFlex 11.3g released

We have just released a minor upgrade to OrcaFlex, version 11.3g. Version 11.3g fixes a number of bugs and adds some minor functionality, including:

  • Support has been added for SHEAR7 version 4.12.
  • Python external functions, post calculation actions and user defined results now support the latest version of Python, version 3.12.

Full details of the changes are described in the documentation:

We intend for this to be the final release of 11.3 because version 11.4 will be released later this month.