OrcaFlex features and specification

• 3D, nonlinear, large displacement analysis
• Fully coupled tension, bending & torsion
• Accurate, efficient and proven FE formulation
• Robust line compression / snatch modelling
• External line-on-line clash & sliding contact
• Internal line-in-line impact & sliding contact
• Modelling of post-contact behaviour
• Linear & nonlinear elastic contact stiffness
• User-defined seabed resistance profiles for lines
• Line slug flow and free-flooding effects
• Tabular contents modelling & expansion tables
• Truss structure modelling tools
• Nonlinear time domain (implicit & explicit)
• Linear frequency domain (1st & 2nd order)
• Quasi-dynamic analysis
• Restart analysis
• Constraints to fix or impose individual DoFs
• Line feeding (haul in and pay out nodes)
• Fully coupled vessel – line analysis
• Fully coupled wind turbine analysis
• OrcaWave diffraction solver

• Comprehensive vessel load modelling
• Multi-body hydrodynamic coupling
• Full sum and full difference QTFs
• Vessel wave shielding (sea state RAOs)
• Water entry & exit slam loads
• Full description of wind, wave and current
• Flat, 2D or 3D seabed profile
• Linear elastic, non-linear hysteretic & P-y soil
• Support for buried lines e.g. for upheaval buckling
• Binary and/or text input files
• Fatigue analysis
• Extreme value statistics
• Modal analysis
• VIV and interference analysis
• Pipelay and riser code checks
• Comprehensive range of automation tools
• Complete Matlab, Python & DLL interfaces
• Parallel processing (at no extra cost)
• Batch processing for volume analyses
• Distributed OrcaFlex optimises multi-licence use
• Full GUI with wire frame and shaded views

Version 11.6 (November 2025)

• Updated shaded graphics
• Improved specification for constraint stiffness & damping
• View filters to customise drawing on a per-view basis
• Line setup wizard can use arbitrary line results variables
• Rotate objects around an arbitrary axis using the move objects wizard
• Compound object properties can account for instantaneous positions
• References report added which lists references between objects
• OrcaWave:
  • Memory usage enhancements
  • User specified body origin
  • Multibody external stiffness and damping matrices
  • Undocked mesh view

Version 11.5 (December 2024)

• Features for modelling buried lines, upheaval buckling and pipe ratcheting
• Support for the modelling of synthetic ropes with rate-dependent stiffness
• Turbine initial rotor angular velocity
• Turbine runtime performance improvements
• Frequency domain solver support for multibody groups
• Data forms can now be modeless, meaning that you can view, and interact with, multiple data forms simultaneously
• OrcaWave:
  • Time domain panel pressure results
  • Spring/dampers
  • Mesh validation performance improvement

LINES

• Fully coupled bending, torsion and axial stiffness
• Bend Stiffener / Tapered Stress Joint model generation
• Pre-bend can be modelled (e.g. spool pieces) now with visualisation tool
• Centrifugal and Coriolis internal flow effects included
• Slug flow and free flooding options for line contents
• Tabular contents modelling & expansion tables
• Multiple coatings and linings can be defined
• Equivalent pipe setup tool
• Bending stiffness, drag and added mass can be non-isotropic
• Axial, bending and torsional stiffness can be nonlinear
• 3D hysteresis model available for bending, axial and torsional effects
• Rayleigh damping with or without geometric stiffness
• Line CofG may be displaced from geometric centre
• Line lengths and end orientations can be automatically calculated based on end positions, e.g. for truss structure modelling
• Clumped line attachments, drag chains or flex joints
• Non-isotropic Coulomb friction with seabed & elastic solids
• Covered sections for buried lines e.g. for upheaval buckling
• Line Clashing for external clash modelling between lines
• Line Contact for pipe-in-pipe, piggybacks, J-tube pulls, bend stiffeners, sliding connections, etc.
• Line feeding for pay out and haul in of nodes
• Hydrodynamic, aerodynamic and user-defined applied loads
• Wake Interference (Huse, Blevins,user specified)
• Partially submerged lines (eg, floating hoses) handled robustly
• Line drag and lift coeffs can vary with Re or seabed proximity
• Added mass as a function of submergence or height above seabed
• Water entry / exit slam loads (per DNV H103, RP-C205)
• Compressibility specified by bulk modulus
• Choice of finite element or analytic catenary representation

TURBINES

• Dedicated horizontal-axis turbine object
• Clockwise or anticlockwise spinning rotor
• Initial rotor angular velocity can be specified
• Aerodynamic loading via Blade Element Momentum (BEM)
• Unsteady aerodynamics models (González / Minnema Pierce)
• Flexible blades capturing aeroelastic coupling effects
• Blade pre-bend
• Drivetrain flexibility (main shaft stiffness & damping)
• Collective or individual blade pitch control
• Prandtl tip and hub loss models
• Pitt and Peters skewed wake model
• Øye dynamic inflow model
• Interface via API to blade pitch and generator torque controllers (e.g. Bladed-style DLLs)
• Choice of tower influence / shadow models
• Rayleigh damping on blades
• Spatially varying wind models including full field (turbulent) wind, as well as linear vertical shear, horizontal shear & gust speed variation

VESSELS

• Imposed vessel displacements:
  • first order displacement RAOs
  • prescribed and / or harmonic motion
  • time history motion files
  • externally calculated
• Loads for calculated vessel motions:
  • first order load RAOs
  • applied loads (thrusters, ice, etc.)
  • 2nd order (low freq.) difference QTFs: full and Newman
  • 2nd order (high freq.) sum QTFs
  • wave drift damping
  • added mass and damping with convolution
  • 6DoF ‘other’ linear and quadratic damping
  • manoeuvring, current and wind loads
  • drag from attached Morison elements
  • loads from attached lines (coupled analysis)
• Multi-body hydrodynamic coupling between floaters
• Sea state RAOs (vessel wave shielding, wave jetting, etc)
• Air gap reporting
• Inertia compensation to avoid double-counting for large superstructures e.g. floating wind turbine

BUOYS

• Full 3D and 6D modelling of buoys
• Lumped option with overall properties
• SPAR option for co-axial cylinders, each with own properties
• Fluid loads calculated based on the instantaneous wetted surface
• Added mass as a function of submergence
• Water entry / exit slam loads (per DNV H103, RP-C205)
• Wings for lifting surfaces
• User-defined imposed loads
• Compressibility specified by bulk modulus
• Coulomb friction with seabed and elastic solids

SHAPES

• Used for modelling boundary surfaces
• Shapes with friction for line & buoy contact
• Plane, cuboid, cylinder (solid/hollow), & bellmouth options
• Trapped water option for moonpool modelling
• Drawing / wire frame options for visualisation purposes

WINCHES

• Winches with several length or tension control options

LINKS

• Links (springs) with linear or nonlinear stiffness & damping

CONSTRAINTS

• Allow individual degrees of freedom for other objects to be constrained
• Imposed motion via time history or externally calculated

SEA

• User-defined water density, kinematic viscosity, temperature
• User-defined horizontal and vertical density variation
• Temperature can be constant or vary with depth
• Kinematic viscosity can be constant or vary with temperature

SEABED

• Horizontal, sloping, 2D or 3D seabed surface (smooth or linear)
• Choice of soil models:
  • linear elastic
  • nonlinear hysteretic (trenching, suction & re-penetration)
  • P-y models (API RP 2A soft clay & sand & user-defined) for vertical and near-vertical line penetration
• Non-isotropic Coulomb friction in both statics & dynamics

WIND

• User-defined air density
• Wind velocity can be constant, NPD, API or ESDU spectra
• Wind can be user defined spectrum / components, or a time history file of speed / direction / shear / gust
• Vertical variation factor specified as a profile
• Full field wind (varies with both space & time)
• Active in statics unless ramped

WAVES

• Regular: Airy, Stokes’ 5th, Dean Stream Function, Cnoidal
• Irregular: ISSC, JONSWAP, Ochi-Hubble, Torsethaugen, Gaussian swell, user-defined, Time History
• Multiple wave trains for combination sea states
• Fluid stretching (Wheeler, kinematic or extrapolation)
• Irregular waves have directional wave spreading option
• Preview and selection of irregular wave profile
• Wave kinematics choice (with individual specification for 3D & 6D buoys and lines):
  • Exact (all nodes/buoys, every time step)
  • Grid interpolation at instantaneous object positions
  • Calculation at object static positions only
• Various wave spectrum discretisation methods:
  • equal-energy (user-defined bounds & interval) – the default
  • equal spacing (arithmetic progression)
  • geometric progression
• Not active in statics

CURRENT

• 3D, non-linear
• Both magnitude and direction can be time varying
• Horizontal variation factor on magnitude
• Active in statics unless ramped

GRAPHICAL USER INTERFACE (GUI)

• Fully interactive native user interface
• Separate fully interactive user interface for OrcaWave diffraction solver
• Visualisation as wire frame and/or shaded graphics
• Shaded graphics uses physically based rendering (PBR) and has perspective, lighting, shadows, etc.
• Moving camera option to track large-scale object motion
• Add text labels at any point in 3D space or attach to objects
• Multiple 3D views with drawing properties controlled via view filters on a per-view basis
• Powerful dockable Model Browser to:
  • organise and manage complex models
  • group objects in logical collections
  • copy / paste objects or groups within or between files
  • show / hide, move and locate objects or groups
  • compare object data
• Compare files with built-in or user-specified compare tools

GUI DATA INPUT

• Readable, structured and self-documenting text files
• Binary files with strong version compatibility
• Drag-and-drop model import from other OrcaFlex files
• Auto import for OrcaWave, AQWA and WAMIT hydrodynamic data
• Generic text file import for other diffraction data
• Graphical RAO realism checks
• Generic line properties through built-in properties wizard
• Wizard for (hysteretic) non-linear moment-curvature data
• Variable Data for non-constant data (drag vs. Re, etc.)

• External functions admit user-defined calculations
• Time history data import for:
  • vessel motions
  • wave elevation
  • wind speed & direction
• SI, US or user-defined units
• Full and comprehensive context sensitive help
• Additional dedicated UI for building pipelay roller supports

GUI RESULTS

• Multiple simultaneous 3D views, results graphs & tables
• Workspace facility to manage windows
• Replay wizard to animate multiple simulations
• AVI file export of animations
• Results displayed at run time and/or simulation replay
• Results storage optimised to minimise file size
• User-defined results can be created if not available as a
  standard result
• Optional embedded Python in OrcaFlex installation, for use with external functions, post-calculation actions, user-defined results, etc.
• GUI output can be:
  • graphical (time histories, range and X-Y graphs)
  • values (in Excel spreadsheet format)
  • statistical analysis (incl. extreme statistics)
• GUI graphs and 3D views can be copy / pasted
• Vessel spectral response reported at any point
• Vessel disturbed sea state and air gap reported at any
  point

• OrcaFlex comes with both 32- and 64-bit executables
• Integral parallel processing for multi-core / processor hardware
• OrcaFlex Excel spreadsheets for:
  • pre-processing for parametric variations of input data (either binary or text files)
  • post-processing to extract results from many output files
• Fully multi-threaded, unattended, batch processing for:
  • data files (binary or text) for static and dynamic analysis
  • batch script files
  • fatigue analysis
  • OrcaFlex post-processing spreadsheet
  • post-processing with Python or command script
• Batch processes above in correct order in case of dependencies
• Low level programmatic interface, targeting C, C++ or Delphi (allows integration with 3rd party applications)
• High-level programmatic interface, targeting Matlab or Python
• Automated execution of SHEAR7 and VIVA from OrcaFlex

• Conversion of storm scatter tables to regular wave scatter tables
• Automation for model building, including:
  • wave search facility
  • Line Type and Plasticity Wizards
  • Line Setup Wizard
• Automation for results, including:
  • vessel response reports
  • fatigue analysis
  • extreme value statistics
• Distributed OrcaFlex optimises use of spare processor time:
  • only of benefit in a multi-licence environment
  • server program co-ordinates and allocates jobs to clients
  • clients can be set to accept or reject jobs
  • client jobs run at low priority (min. impact on other tasks)
  • client jobs can be aborted and server will re-allocate
• Orcina Licence Monitor allows monitoring of OrcaFlex use

• Fatigue calculations are all multi-threaded
• Regular, rainflow & spectral (frequency domain and response RAOs) fatigue analysis options
• 5 fatigue damage calculation options:
  • homogeneous pipe (S-N curves)
  • stress factors for different cross-section layers (S-N curves)
  • mooring (T-N curves)
  • SHEAR7 (damage results collated & presented in OrcaFlex)
  • user-defined externally calculated stress (via external functions)
• S-N and T-N curves can be tabulated or set parametrically

• S-N curves have option of 4 mean stress models
• Analysis at multiple circumference points on ID and OD
• Analysis at multiple line positions, each with different:
  • stress concentration factors
  • thickness factors
  • S-N curves (or T-N curves for moorings)
• Damage results as tables and / or graphs for overall damage or damage from individual cases
• Histogram collation and individual histogram results also available

OVERVIEW

• Uses the leading methods for the analysis of VIV
• All methods are coupled, applying VIV loads to the line
• Generalised to 3D behaviour (not just 2D)
• Highly efficient as all VIV models use same FE model
• Tested and fully documented SHEAR7 and VIVA interfaces
• Quality-assured implementation of time domain models
• Consistent results comparison from different VIV models

SHEAR7 & VIVA INTERFACES

• Export input data to run SHEAR7 / VIVA off-line from OrcaFlex
• Call either directly from OrcaFlex with either a user-specified or OrcaFlex-derived mode shape file
• Automatically selects transverse modes for mode shape file
• OrcaFlex statics couples with SHEAR7 / VIVA enhanced drag
• Results (incl. fatigue) presented in OrcaFlex; for SHEAR7, optionally aggregate fatigue damage via the OrcaFlex fatigue form

WAKE OSCILLATOR MODELS

• Milan or Iwan and Blevins wake oscillator models
• Model VIV suppression by turning off for selected line sections
• In-line drag enhancement included

VORTEX TRACKING MODELS

• Two approaches which model the physics of VIV
• Both in-line and transverse VIV effects included
• Boundary layer theory for stagnation and separation points
• Inviscid Navier-Stokes equation used outside the boundary layer
• Much less computationally demanding than full CFD

• Calculates loading and response for wet bodies due to
  surface water waves
• Utilises potential flow theory, outputs include:
  • load RAOs (choice of Haskind or diffraction methods)
  • displacement RAOs
  • added mass and damping matrices
  • Newman QTFs (choice of pressure integration or control
    surface methods)
  • full QTFs (sum and/or difference frequencies, direct or
    indirect methods)
  • sea state RAOs
• Can include dipole panels for thin walled structural elements with fluid on both sides e.g. strakes or heave plates
• Can include Morison elements

• Single or multibody analysis
• Bodies can be rigidly connected e.g. for modelling the separate hulls of a semisub or catamaran
• Choice of direct or iterative linear solvers
• Support for multiple mesh file formats (WAMIT.gdf,
  Nemoh.dat, Aqwa.dat, Sesam.fem, Hydrostar.hst,
  Gmsh.msh)
• Mesh view and validation tool allows easy checking of
  mesh geometry
• Intermediate results to enable first-order calculations to be
  reused in related analyses for processing efficiency
• Seamless transfer of data to OrcaFlex
• Batch processing
• Automation via OrcFxAPI

• Finite element with 6 DoF at each node
• Constraints to fix or impose individual DoFs
• Connect mid-Line nodes to other objects
• Optional 3 DoF line element for optimal performance
• Element formulation is extremely robust and accurate
• Element is proven and widely applicable
• Fully coupled tension, bending and torsion
• Full 3D model building and analysis
• Non-linear large displacement analysis
• Variety of dynamic solution methods:
  • Nonlinear time domain implicit (constant or variable Δt)
  • Nonlinear time domain explicit
  • Linear frequency domain (1st & 2nd order)
• FFT reconstruction of wave field from wave elevation time history
• Fluid forces based on Morison and cross-flow assumptions

• 3 optimisations for wave kinematics calculations
• Extremely quick and robust static analysis
• Dynamics ramped-up (to eliminate starting transients)
• Robust line compression and snatch load modelling
• Line and system modal analysis (shapes and loads)
• Contact, clashing and clearance analysis
• Linear & non-linear elastic contact stiffness for seabed, elastic solids, line contact and supports
• Vessel manoeuvres (forward speed and turn rate)
• Coupled and uncoupled vessel / line analysis
• Surface piercing fully modelled
• Setup Wizard to set line length for target end conditions
• Pressure effects on line EI can be separate for statics & dynamics
• Code checks (API RP 2RD, API RP 1111, DNV OS F101, DNV OS F201 and PD 8010)