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ContentsIn this newsletter 1Diffraction 1Turbine enhancements 3

Line enhancements 4

User interface 5

Software licensing 6

Coming up 7

And finally 7The back page 8

Orcina Limited+44 (0)1229 584 742orcina@orcina.comwww.orcina.com

In this NewsletterOrcaFlex 11.0 was released towardsthe end of 2019 and was distributedto all customers with up–to–dateMUS contracts.

This newsletter reviews some of thenew features in 11.0, and also thosethat we hope to introduce in 11.1towards the end of 2020.

DiffractionOrcaWave is here!

In the 2019 newsletterwe previewed the early progress wewere making on the development ofa diffraction code. We are pleasedto say that this has been released aspart of OrcaFlex 11.0. OrcaWave islicensed as part of OrcaFlex, butruns as a separate executable.

OrcaWave capabilities:• First & second order calculations• Single & multibody analyses• Sea state RAOs• Seamless transfer of data from

OrcaWave into OrcaFlex.

The user interface is very simple incomparison to OrcaFlex. Data andresults are spread across a numberof pages, but all in a single window.

After a diffraction analysis has beenrun, the resultant OrcaWave resultsfile can be imported directly into anOrcaFlex vessel type with minimaleffort.

OrcaWave user interface

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A look at the user interface

The data for an OrcaWave analysis is entered andreviewed using a number of pages. Some of these,such as the units and drawing pages, will be veryrecognisable to OrcaFlex users, others less so. Havingsaid that, even the 'new' pages will be somewhatfamiliar, since the look and feel is very similar toOrcaFlex.

We have made no attempt to implement anymeshing functionality in OrcaWave. Instead we relyon users providing panel meshes. Perhaps at somepoint in the future we may add meshing, but it iscurrently not high on our priority list. At Orcina wehave used, for example, Rhino to produce meshesand no doubt users are familiar with plenty of othermeshing tools. OrcaWave can accept meshes inWamit .gdf, Nemoh .dat, and Hydrostar .hst format,but we expect the list of supported formats to growin future releases.

We have thought hard about the mesh visualisationfunctionality. The quality of diffraction analysisfrequently hinges on the quality of the providedmesh. Being able to visualise that mesh aids hugelyin diagnosing problems with your analysis. The viewoptions allow you to select exactly what is displayed.The highlight option allows you to identify specificpanels from the mesh, and works very smoothly withthe mesh validation feature of OrcaWave.

There is a batch processing window similar to that ofOrcaFlex. The output can be viewed graphically (forRAOs, added mass and damping), and is available intabular form. These tables can be saved as Excelworkbooks. The OrcaFlex API has been extended toinclude diffraction, so all the functionality is nowavailable from Python or MATLAB.

What about results?

Results from the analysis are available in bothgraphical and tabular form. OrcaFlex is able toimport hydrodynamic data from OrcaWave analyses,and because the two programs are designed to worktogether there is none of the uncertainty overconventions that can sometimes arise whenimporting hydrodynamic data.

Help!

As with OrcaFlex, you can find full details ofOrcaWave's capabilities in the documentation,available contextually via F1, or from our website.

OrcaWave data input & data review pages

OrcaWave mesh view

OrcaWave results graphs page

Mesh view showing highlighted panels

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Validation

We have validated OrcaWave by comparing itsoutput to that of Wamit, for cases covering the entirerange of functionality of OrcaWave. This validationexercise will be turned into a published documentover the next few months.

What's next for diffraction?

There is some desirable functionality that we didn'thave time to implement in this first release ofOrcaWave. One of the biggest improvements weintend to make in the next development cycle is toadd the option of using iterative solvers as analternative to the current direct matrix solvers. Weare aware that, for large meshes, performance canbe greatly improved in this way. We are sure thatusers will have many other feature requests, and welook forward to receiving such feedback andprioritising future developments.

Turbine enhancementsLast year we introduced the OrcaFlex wind turbineobject, designed for modelling horizontal axis windturbines, and allowing for the first time a fullycoupled floating wind turbine analysis without theneed for interfacing with FAST.

We have made a number of enhancements to theturbine object:

Tower influence modelling

The wind field experienced by the rotor can beinfluenced by the tower that is downwind of it, theso–called tower dam effect. The turbine can now beassociated with a tower by choosing from two towerinfluence models.

Based on potential theory, these models allow thetower’s influence on the undisturbed wind field to beaccounted for.

Dynamic inflow

The Øye dynamic inflow model is now available as anoption when calculating the rotor aerodynamicloading. This accounts for the time that the turbine’swake takes to adjust to a change of flow conditions.

Individual blade pitch control

This is a feature that was requested by a number ofusers after the introduction of the turbine object inversion 10.3.

Blade pitch angle can now be controlled forindividual blades. There is a new data item on theturbine data form called pitch control mode. Ifcommon is selected, then all blades share the samepitch angle, as was the behaviour in previousversions. If individual is selected then each bladehas an independent pitch value.

Slave connections

In version 10.3, slave objects were always connectedto the turbine hub. They can now be connected to anindividual blade at any arc length. Why might youwant to do this? The following are potential casesthat may benefit:

• Simulating rotor mass imbalance from things likeice build–up or manufacturing defects.

• As a means of applying externally calculatedloads.

• Modelling installation scenarios.

Tower influence options

Blade individual pitch control

Turbine blade slave connections

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Rayleigh damping

The finite element modelling approach for turbineblades is very similar to that of lines, and you cannow specify Rayleigh damping coefficients for theturbine blade using the same model and dataspecification.

Convergence monitoring start time

When the BEM calculation is being performed,convergence problems are more likely at thebeginning of a simulation. This is because the rotorspeed is low and the wind velocity is typically beingramped up from zero. As with the build-up of wavesin OrcaFlex, this phase can be regarded as transientand is often not of interest. Any BEM warningsgenerated in this period can therefore be misleading.

It is now possible to suppress reporting of any BEMconvergence warnings that arise before this time.

New results

The following new results are now available forturbines:

• blade deflections• tower and line clearances• rotor aerodynamic load and power• rotor aerodynamic thrust and power coefficients• rotor swept area• skew angle• disc averaged wind velocity• extra BEM output

Line enhancementsLines have always been one of the most fundamentalof OrcaFlex building blocks, and we have introduceda number of improvements to this object for v11.0.

Reset drawing using analytic catenary

Up until now, lines drawn in the reset state haven'tpaid any attention to the seabed, known as the quickcatenary algorithm. OrcaFlex users will be veryfamiliar with the first of the following images, of aline hanging below the seabed in the reset state.

In version 11.0, the default behaviour for the resetstate is to attempt to use the analytic catenary solver(the solver was introduced in version 10.3 for thepurpose of performing quasi dynamic analysis) asshown in the second image. This will account for flatseabeds and buoyant line sections, and is intendedto aid visualisation whilst model building. Note that itdoesn't have any impact on calculation.

Slug flow drawing

There is now an option on the line data form to drawslugs in the 3D view. This is a very useful tool forvisualisation of the slug flow settings, and is availablefor both wireframe and shaded graphics views.

Line reset representation – quick

Line reset representation – analytic catenary

Line slug flow visualisation – wireframe view

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Line velocity and acceleration results logging

Line velocity and acceleration results can now,optionally, be logged (these values were previouslyonly derived). This will result in more accuratevelocity and acceleration results (and obviously otherresults which also use them) but will come at a cost,namely increased simulation file size.

New results variables

The following new line results have been added:

• x and y relative velocities• drag and lift forces• fluid inertia forces• Morison forces

The accuracy of these results depends on the newlyintroduced logging of velocity and accelerationresults mentioned in the previous section.

User interface enhancementsThe OrcaFlex user interface is renowned for itssimplicity and user–friendliness. However, we arealways looking for ways to improve it. Here are a fewchanges for this release:

Vessel and 6D buoy origin drawing

Something that users have enquired about for sometime is the ability to visualise the various origins forvessels and 6D buoys. Indicator marks can now beoptionally drawn to show things like centre of gravity,centre of buoyancy, diffraction origins, etc.

In the 6D spar buoy in the image above, the yellowmark indicates the location of the CoG (input data)and the blue mark indicates the centre of buoyancy.

Note that for a spar buoy the centre of buoyancy isautomatically calculated by OrcaFlex based on itsgeometry.

This can be set as a preference and can also bemodified from the view menu and with keyboardshortcut SHIFT+ALT+Y.

Panel mesh file drawing, wire frame and shadedgraphics

Panel mesh files can now be used for both wireframe vertices and edges, and shaded graphicsmodel import.

The formats currently supported are WAMIT .gdf,Nemoh .dat and Hydrostar .hst.

Summary and full results types combined

This is a relatively minor change but may be ofinterest to our more experienced users. Prior toversion 11.0, there were options for both Summaryand Full results, the difference being that for lines,summary results reported only at the ends, and fullresults included tables for each segment on the line.

These results types have now been combined intoone, providing by default the full results. A check box,report abbreviated summary, allows the reportingof only the line ends as with the previous summaryresults option.

6D buoy origins

Results windows – v10.3 and v11.0

Wire frame and shaded graphics mesh import

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Summary results windows are immortal

In previous versions of the program, the summaryresults windows were closed by the program when amodel was reset. This resulted in a suboptimalworkflow when experimenting or debugging duringmodel building, with the user having to reopen theresults windows every time a new analysis was run.

These windows are now immortal, meaning that theystay open even when the model is reset. Instead thewindow is cleared and repopulated next time thereare results available (i.e. when a new analysis is run).

Floating point / text conversion changes

It is now possible to specify, as a user preference, theminimum number of digits after the decimal point. Ifthis value is set to 0, round numbers will have nodecimal point, and for non–round numbers, theprogram will display as many as required (whereexact values are specified), or as many as possiblewithin the designated space.

Hover over a number and the tooltip will show thefull precision value.

View specification relative to...

It has long been possible to specify a view relative toa particular object. However, until now, 3D buoys andturbine objects have not been available as an option.

This was a simple omission on our part which hasnow been rectified.

Software licensingWe have been working on integrating FlexnetPublisher (formerly flexlm) software-based licensinginto OrcaFlex. This will allow us to offer dongle freeand time limited licensing. The former is importantfor environments using virtual machines which donot have physical hardware ports, while the latter isuseful for short term leases and loans, and whentaking a computer into an environment where it is atrisk of being lost or stolen (e.g. offshore).

Once in–place, this will allow us to investigate thepossibilities for so–called 'OrcaFlex in the cloud', aworkflow which some third parties are alreadyoffering, and a concept which is becomingcommonplace in the world of software. But don't gettoo excited by this, as it will still be some time beforewe are able to offer cloud licensing ourselves!

Software licensing is being trialled internally but thetools for handling it with external clients are not yetin place. Look out for more news on this soon.

Other developmentsThose are the headlines, now here are a few otherimprovements we’ve made to make yourOrcaFlex–using life a bit easier.

Constraint hysteretic stiffness

When we introduced constraints in version 10.1, theyimmediately proved useful for a wide range ofapplications. They can now be used to model friction-like phenomena with the introduction of hystereticstiffness. This will make the modelling of things likebreakout friction in FPSO turrets much easier.

Wind drag loading for 6D buoys

Time to deal with another prior omission – in earlierversions of OrcaFlex, wind loads applied only tovessels, lines and 6D buoy wings.

Version 11.0 now enables wind drag loading on 6Dbuoys without the need to add wing elements.

Bringing your own wind to the party?

Now that you can include wind loads on 6D buoys,what if you wanted to define your own windspectrum? This is now possible in exactly the sameway as waves, with options for either user definedspectrum or user specified components options.

New display options for numbers in OrcaFlex

View parameters

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In addition, the ESDU spectrum is now available as abuilt–in option, allowing for the simulation of tropicalcyclone conditions (previously the only options werethe NPD and API spectra).

Vessel enhancements

Current and wind load: Prior to version 11.0,current and wind load data only allowed coefficientsfor surge, sway and yaw. This has now beenextended to include heave, roll and pitch.

Sea state results: It is now possible to query a vesselfor disturbed sea state results at specific points onthe vessel – previously this required the inclusion ofadditional buoy or line objects.

Air gap results: As part of the above sea stateresults development, it is also now possible to queryair gap results. These represent the vertical clearanceof a chosen point on a vessel above a scaledinstantaneous sea surface. This is something thatwasn't available in previous versions and has its owndedicated page on the vessel data form:

Coming upAs always, we have an extensive list of developmentswe hope to be working on in the near future. It is tooearly to say exactly what will appear in the nextversion, but our current priorities are as follows:

Lateral soil modelling

We have talked for many years about the need toimprove the lateral soil model in OrcaFlex, and thisdevelopment will be particularly useful for thoseperforming pipeline seabed stability analysis.

Restarts

Again driven by a desire to improve our pipelineanalysis tools but also useful for many otherapplications, we are working on restarts.

Pipe temperature and pressure effects

Currently only possible using an expansion factor,another major piece of the pipeline analysis puzzlewill be to allow for pipe thermal and pressure effects.

Improved mooring analysis tools

We still intend to work towards making mooringanalysis easier in OrcaFlex, including a workflowtailored to this application, better extremes results,etc.

And finally...In the last newsletter we presented our newlyupdated logo and also told you that a new websitewas coming soon...

Well, the new site went live in May, redesigned fromthe ground up with the aim of making it easier tonavigate, optimised for mobile devices, and withsome new information and resources.

We have had a great deal of positive feedback aboutthe new website, and we hope you like it too.

Video content

There is a comprehensive videos page(orcina.com/resources/videos) which includes what'snew videos for recent releases as well as a set ofshort OrcaFlex tutorial videos, designed to answerthose commonly asked OrcaFlex questions. If youthink the wider audience would benefit from atutorial video which isn't yet covered, we would loveto hear your suggestions. Contact information is onthe back page.

Prefer to read? We've got you covered...

The resources section features a literature page(orcina.com/resources/literature) where you candownload the usual mix of brochures and technicalspecifications, as well as some application-specificfliers. These include pipelay and offshore wind, andwe are in the process of writing a flier for diffraction.

UGM materials – a hidden gem

There is a very useful archive of past user groupmaterials in the resources section(orcina.com/resources/ugm-material). Whilst not anew addition, this wasn't easy to find on the old site,and consequently many users weren't aware of it.

What about us?

The old website didn't really divulge that muchinformation about us as a company, so with the newone we have tried to present more of our humanside. The 'About Orcina' section (orcina.com/about)provides information about the history of thecompany, as well as bios for a few of the less camera-shy members of our team...!

Air gap page - vessel data form

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Orcina Limited+44 (0)1229 584 742orcina@orcina.comwww.orcina.com

tthhee bbaacckk ppaaggeeOrcina AgentsOrcina is supported in its marketing andtechnical support activities by thefollowing agents:

USA, Canada & MexicoJacob TechnologiesPaul Jacobpj@jtec-tx.com+1 713 398 9595Heron OffshoreDongmei Chudchu@heronoffshore.com+1 832 725 2438

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Social MediaIf you use LinkedIn please follow us:Orcina Ltd - the home of OrcaFlex

News

We aim to publish theseNewsletters yearly to complementeach OrcaFlex release. Around thesame time we also produce a video(see orcina.com/resources/videos)as some features are best seendynamically rather than on a staticpage.

We do also try to keep you up todate with developments on a morefrequent basis. Our companyLinkedIn page has been going for awhile now, atlinkedin.com/company/orcina-ltd.New followers are always welcome.

Our News page may be useful as asource of more detail on some ofthe v11.0 developments: these areall wrapped up in a recent post,orcina.com/news/orcaflex-110.Future posts will cover, amongother things, 11.1 plans anddevelopments.

Out and About

During 2019, as well as the usualmix of training courses and UGMs(see below), we were also involvedin a number of exhibitions. 2020 willbe no different, and will see usexhibiting at Subsea Expo(Aberdeen), Subsea Tieback (SanAntonio), Oceanology (London),Global Offshore Wind (Manchester),OMAE (Florida), AWEA WindConference (Boston), Oceans(Mississippi).

We will also be attending OPT(Amsterdam) and Subsea Lifting(Stavanger).

Keep an eye on the website for upto date event information:orcina.com/support/events

Training

We continue to offer trainingcourses, both for OrcaFlex and forthe Python interface to OrcaFlex.

Planned courses are listed atorcina.com/support/training. Inaddition, we are always open torequests for client–specific training,whether it is our standardintroduction to OrcaFlex, Pythonautomation, or more advanced andtailored to your specificrequirements.

User Group Meetings

In 2019 we again held 11 UserGroup meetings at various locationsaround the world, includingHouston, London, Aberdeen,Stavanger, Amsterdam, KualaLumpur, Jakarta, Singapore, Perth,Shanghai and Rio. Content fromthese can be found atorcina.com/support/ugm. We alsoheld our 'Introduction to Python’workshop in Houston andUlverston.

Thanks to all who attended andcontributed to their continuingsuccess.

2020 UGMs will run betweenSeptember and December – we’llpost details of these and otherevents onorcina.com/support/events and onLinkedIn.

It is likely that we will also holdPython workshops in 2020: theseare yet to be decided, but again,we’ll post details as soon as we havethem.