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!
We have just released a minor upgrade to OrcaFlex, version 11.4d. Version 11.4d 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 11.4d.
To upgrade to OrcaFlex 11.4d 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.
The example illustrates how to access the OrcaFlex interface to SHEAR7, using the steel catenary riser system considered in the A05 Catenary with spar example.
SHEAR7 is a third-party program, distributed by AMOG, which performs frequency domain VIV analysis for the purpose of estimating fatigue and/or drag amplification due to VIV. A separate licence is required to run SHEAR7 through the interface. However, the example results can be viewed without a SHEAR7 licence.
The accompanying PDF document provides detail on how to access the interface, what input data are required and how to access the VIV results. However, the example does not address how to choose appropriate values for the SHEAR7 data inputs, as these relate to SHEAR7 itself, rather than the OrcaFlex interface.
We hope that the example provides a useful guide to the SHEAR7 interface, allowing it to be used effectively.
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 photovoltaic (FPV) array.
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 MW reference wind turbineComparison of the aerodynamic and operational steady-state response of the 22 MW rotorComparison of the blade and tower response to turbulent wind
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.
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.
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.
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:
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:
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:
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.
