API

Simulation Class

class objects.simulationClass

The simulationClass creates a simu object saved to the MATLAB workspace. The simulationClass includes properties and methods used to define WEC-Sim’s simulation parameters and settings.

simulationClass: This method initializes the simulationClass.

Constructor Summary

Property Summary

b2b: WEC-Sim input

cicDt: (float) Time step to calculate Convolution Integral. Default = dt

cicEndTime: (float) Convolution integral time. Default = 60 s

domainSize: (float) Size of free surface and seabed. This variable is only used for visualization. Default = 200 m

dt: (float) Simulation time step. Default = 0.1 s

dtOut: (float) Output sampling time. Default = dt

endTime: (float) Simulation end time. Default = []

explorer: (string) SimMechanics Explorer ‘on’ or ‘off’. Default = 'on'

gravity: (float) Acceleration due to gravity. Default = 9.81 m/s

mcrMatFile: (string) mat file that contain a list of the multiple conditions runs with given conditions. Default = []

mcrExcelFile: (string) File name from which to load wave statistics data. Default = []

mode: (string) Simulation execution mode, ‘normal’, ‘accelerator’, ‘rapid-accelerator’. Default = 'normal'

morisonDt: (float) Sample time to calculate Morison Element forces. Default = dt

nonlinearDt: (float) Sample time to calculate nonlinear forces. Default = dt

paraview

0 (off) , 1 (on). Default = 0. startTime (float) Start time for the vtk file of Paraview. Default = 0. endTime (float) End time for the vtk file of Paraview. Default = 100. dt (float) Timestep for Paraview. Default = 0.1. path (string) Path of the folder for Paraview vtk files. Default = 'vtk'.

Type:: (structure) Defines the Paraview visualization. option (integer) Flag for paraview visualization, and writing vtp files, Options

pressure

0 (off), 1 (on). Default = 0

Type:: (integer) Flag to save pressure distribution, Options

rampTime: (float) Ramp time for wave forcing. Default = 100 s

rateTransition

‘on’, ‘off’. Default = 'on'

Type:: (string) Flag for automatically handling rate transition for data transfer, Opyions

reloadH5Data

0 (off), 1 (on). Default = 0

Type:: (integer) Flag to re-load hydro data from h5 file between runs, Options

rho: (float) Density of water. Default = 1000 kg/m^3

saveStructure

0 (off), 1 (on). Default = 0

Type:: (integer) Flag to save results as a MATLAB structure, Options

saveText

0 (off), 1 (on). Default = 0

Type:: (integer) Flag to save results as ASCII files, Options

saveWorkspace

0 (off), 1 (on). Default = 1

Type:: (integer) Flag to save .mat file for each run, Options

simMechanicsFile: (string) Simulink/SimMechanics model file. Default = 'NOT DEFINED'

solver: (string) PDE solver used by the Simulink/SimMechanics simulation. Any continuous solver in Simulink possible. Recommended to use ‘ode4, ‘ode45’ for WEC-Sim. Default = 'ode4'

stateSpace

0 (convolution integral), 1 (state-space). Default = 0

Type:: (integer) Flag for convolution integral or state-space calculation, Options

FIR

0 (convolution integral), 1 (FIR). Default = 0

Type:: (integer) Flag for FIR calculation, Options

startTime: (float) Simulation start time. Default = 0 s

zeroCross: (string) Disable zero cross control. Default = 'DisableAll'

numMoorDyn: (integer) Number of moordyn blocks systems in the wec model. Default = 0

Method Summary

Wave Class

class objects.waveClass

The waveClass creates a waves object saved to the MATLAB workspace. The waveClass includes properties and methods used to define WEC-Sim’s wave input.

Constructor Summary

Property Summary

bem: input file

current

0 for depth-independent model, 1 for 1/7 power law variation with depth, 2 for linear variation with depth, or 3 for no current. Default = 3, depth (float) Current depth [m]. Define the depth over which the sub-surface current is modeled. Must be defined for options 1 and 2. The current is not calculated for any depths greater than the specified current depth. Default = 0, direction (float) Current direction [deg]. Surface current direction defined using WEC-Sim global coordinate system. Default = 0, speed (float) Current seed [m/s]. Surface current speed that is uniform along the water column. Default = 0

Type:: (structure) Defines the current implementation. option (integer) Define the sub-surface current model to be used in WEC-Sim, options include

direction: (float) Incident wave direction(s) [deg]. Incident wave direction defined using WEC-Sim global coordinate system. Should be defined as a row vector for more than one wave direction. Default = 0

elevationFile: (string) Data file that contains the times-series data file. Default = 'NOT DEFINED'

gamma: (float) Defines gamma, only used for JS wave spectrum type. Default = []

height: (float) Wave height [m]. Defined as wave height for regular, or significant wave height for irregular. Default = 'NOT DEFINED'

marker

Sphere, 2: Cube, 3: Frame. Default = 1: Sphere

Type:: (structure) Defines the wave marker. loc (nx2 vector) Marker [X,Y] locations [m]. Default = []. size (float) Marker size in Pixels. Default = 10. style Marker style, options include
Type:: 1

period: (float) Wave period [s] . Defined as wave period for regular, peak period for irregular, or period of BEM data used for hydrodynamic coefficients for noWave. Default = 'NOT DEFINED'

phaseSeed: (integer) Defines the random phase seed, only used for irregular and spectrumImport waves. Default = 0

spectrumFile: (string) Data file that contains the spectrum data file. Default = 'NOT DEFINED'

spectrumType

PM or JS. Default = 'NOT DEFINED'

Type:: (string) Specifies the wave spectrum type, options include

viz: (structure) Defines visualization options, structure contains the fields numPointsX for the number of visualization points in x direction, and numPointsY for the number of visualization points in y direction.

waterDepth: (float) Water depth [m]. Default to BEM water depth if not set.

spread: (float) Wave Spread probability associated with wave direction(s). Should be defined as a row vector for more than one wave direction. Default = 1

freqDepDirection: (float) used only in importSpectraFullDir, defines the multiple of spread values (+/-) over which bin energy will be evaluated. Default = 2

Method Summary

plotElevation(rampTime)

This method plots wave elevation time-history.

Parameters:: rampTime (float, optional) – Specify wave ramp time to include in plot
Returns:: figure – Plot of wave elevation versus time
Return type:: fig

plotSpectrum()

This method plots the wave spectrum.

Returns:: figure – Plot of wave spectrum versus wave frequency
Return type:: fig

Body Class

class objects.bodyClass

The bodyClass creates a body object saved to the MATLAB workspace. The bodyClass includes properties and methods used to define WEC-Sim’s hydrodynamic and non-hydrodynamic bodies.

bodyClass

This method initializes the bodyClass and creates a body object.

Parameters:: h5File (string) – String specifying the location of the body h5 file
Returns:: body – bodyClass object
Return type:: obj

Constructor Summary

Property Summary

adjMassFactor: WEC-Sim input

centerBuoyancy: (3x1 float vector) Body center of buoyancy [m]. Defined in the following format [x y z]. For hydrodynamic bodies this is defined in the h5 file while for nonhydrodynamic bodies this is defined by the user. Default = [].

centerGravity: (3x1 float vector) Body center of gravity [m]. Defined in the following format [x y z]. For hydrodynamic bodies this is defined in the h5 file while for nonhydrodynamic bodies this is defined by the user. Default = [].

dof: (integer) Number of degree of freedoms (DOFs). For hydrodynamic bodies this is given in the h5 file. If not defined in the h5 file, Default = 6.

excitationIRF: (vector) Defines excitation Impulse Response Function, only used with the waveClass elevationImport type. Default = [].

flex

0 (off) or 1 (on). Default = 0.

Type:: (integer) Flag for flexible body, Options

gbmDOF: (integer) Number of degree of freedoms (DOFs) for generalized body mode (GBM). Default = [].

geometryFile: (string) Path to the body geometry .stl file.

h5File: (char array, string, cell array of char arrays, or cell array or strings) hdf5 file containing the hydrodynamic data

hydroStiffness: (6x6 float matrix) Linear hydrostatic stiffness matrix. If the variable is nonzero, the matrix will override the h5 file values. Create a 3D matrix (6x6xn) for variable hydrodynamics. Default = zeros(6).

inertia: (1x3 float vector) Rotational inertia or mass moment of inertia [kg*m^{2}]. Defined by the user in the following format [Ixx Iyy Izz]. Default = [].

inertiaProducts: (1x3 float vector) Rotational inertia or mass products of inertia [kg*m^{2}]. Defined by the user in the following format [Ixy Ixz Iyz]. Default = [].

initial: (structure) Defines the initial displacement of the body. displacement (1x3 float vector) is defined as the initial displacement of the body center of gravity (COG) [m] in the following format [x y z], Default = [0 0 0]. axis (1x3 float vector) is defined as the axis of rotation in the following format [x y z], Default = [0 1 0]. angle (float) is defined as the initial angular displacement of the body COG [rad], Default = 0.

linearDamping: (6x6 float matrix) Defines linear damping coefficient matrix. Create a 3D matrix (6x6xn) for variable hydrodynamics. Default = zeros(6).

mass: (float) Translational inertia or mass [kg]. Defined by the user or specify ‘equilibrium’ to set the mass equal to the fluid density times displaced volume. Default = [].

meanDrift

0 (no), 1 (yes, from control surface) or 2 (yes, from momentum conservation). Default = 0.

Type:: (integer) Flag for mean drift force, Options

morisonElement

0 (off), 1 (on) or 2 (on), Default = 0, Option 1 uses an approach that allows the user to define drag and inertial coefficients along the x-, y-, and z-axes and Option 2 uses an approach that defines the Morison Element with normal and tangential tangential drag and interial coefficients. cd (1x3 float vector) is defined as the viscous normal and tangential drag coefficients in the following format, Option 1 [cd_x cd_y cd_z], Option 2 [cd_N cd_T NaN], Default = [0 0 0]. ca is defined as the added mass coefficent for the Morison Element in the following format, Option 1 [ca_x ca_y ca_z], Option 2 [ca_N ca_T NaN], Default = [0 0 0], area is defined as the characteristic area for the Morison Element [m^2] in the following format, Option 1 [Area_x Area_y Area_z], Option 2 [Area_N Area_T NaN], Default = [0 0 0]. VME is the characteristic volume of the Morison Element [m^3], Default = 0. rgME is defined as the vector from the body COG to point of application for the Morison Element [m] in the following format [x y z], Default = [0 0 0]. z is defined as the unit normal vector center axis of the Morison Element in the following format, Option 1 not used, Option 2 [n_{x} n_{y} n_{z}], Default = [0 0 1].

Type:: (structure) Defines the Morison Element properties connected to the body. option (integer) for Morison Element calculation, Options

name: (string) Specifies the body name. For hydrodynamic bodies this is defined in h5 file. For nonhydrodynamic bodies this is defined by the user, Default = [].

nonHydro

0 (hydro body), 1 (non-hydro body), 2 (drag body). Default = 0.

Type:: (integer) Flag for non-hydro body, Options

nonlinearHydro

0 (linear), 1 (nonlinear), 2 (nonlinear). Default = 0

Type:: (integer) Flag for nonlinear hydrohanamics calculation, Options

quadDrag: (structure) Defines the viscous quadratic drag forces. Create an array of structures for variable hydrodynamics. First option define drag, (6x6 float matrix), Default = zeros(6). Second option define cd, (1x6 float vector), Default = [0 0 0 0 0 0], and area, (1x6 float vector), Default = [0 0 0 0 0 0].

QTFs

0 (off), 1 (on). Default = 0

Type:: (integer) Flag for QTFs calculation, Options

paraview

0 (no) or 1 (yes). Default = 1, only called in paraview.

Type:: (integer) Flag for visualisation in Paraview either, Options

variableHydro: (structure) Defines the variable hydro implementation. option (float) Flag to turn variable hydrodynamics on or off. hydroForceIndexInitial (float) Defines the initial value of the hydroForceIndex, which should correspond to the hydroForce data (cg, cb, volume, water depth, valid cicEndTime, added mass integrated with the body during runtime) and h5File of the body at equilibrium.

viz: (structure) Defines visualization properties in either SimScape or Paraview. color (1x3 float vector) is defined as the body visualization color, Default = [1 1 0]. opacity (integer) is defined as the body opacity, Default = 1.

volume: (float) Displaced volume at equilibrium position [m^{3}]. For hydrodynamic bodies this is defined in the h5 file while for nonhydrodynamic bodies this is defined by the user. Default = [].

yaw

0 (off), 1 (on). Default = 0. threshold (float) Yaw position threshold (in degrees) above which excitation coefficients will be interpolated in passive yaw. Default = 1 [deg].

Type:: (structure) Defines the passive yaw implementation. option (integer) Flag for passive yaw calculation, Options

Method Summary

setInitDisp(relCoord, axisAngleList, addLinDisp)

Function to set a body’s initial displacement

This function assumes that all rotations are about the same relative coordinate. If not, the user should input a relative coordinate of 0,0,0 and use the additional linear displacement parameter to set the centerGravity or location correctly.

Parameters:

relCoord ([1 3] float vector) – Distance from x_rot to the body center of gravity or the constraint or pto location as defined by: relCoord = centerGravity - x_rot. [m]
axisAngleList ([nAngle 4] float vector) – List of axes and angles of the rotations with the format: [n_x n_y n_z angle] (angle in rad) Rotations applied consecutively in order of dimension 1
addLinDisp ([1 3] float vector) – Initial linear displacement (in addition to the displacement caused by rotation) [m]

plotStl(): Method to plot the body .stl mesh and normal vectors.

calculateForceAddedMass(acc)

This method calculates and outputs the real added mass force time history. This encompasses both the contributions of the added mass coefficients and applied during simulation, and the component from added mass that is lumped with the body mass during simulation.

This function must be called after body.restoreMassMatrix() and body.storeForceAddedMass()

Parameters:

obj (bodyClass) – Body whose added mass force is being updated
acc (float array) – Timeseries of the acceleration at each simulation time step

Returns:

actualAddedMassForce – Time series of the actual added mass force

Return type:

float array

Constraint Class

class objects.constraintClass

The constraintClass creates a constraint object saved to the MATLAB workspace. The constraintClass includes properties and methods used to define constraints between the body motion relative to the global reference frame or relative to other bodies.

constraintClass

This method initilizes the constraintClass and creates a constraint object.

Parameters:: filename (string) – String specifying the name of the constraint
Returns:: constraint – contraintClass object
Return type:: obj

Constructor Summary

Property Summary

hardStops: input file

initial: (structure) Defines the initial displacement of the constraint. displacement (3x1 float vector) is defined as the initial displacement of the constraint [m] in the following format [x y z], Default = [0 0 0].

extension: (string) Specify priority level for extension. `` ‘High’ or ‘Low’ `` Default = High.

location: (1x3 float vector) Constraint location [m]. Defined in the following format [x y z]. Default = [999 999 999].

name: (string) Specifies the constraint name. For constraints this is defined by the user, Default = NOT DEFINED.

orientation: (structure) Defines the orientation axis of the constraint. z (1x3 float vector) defines the direciton of the Z-coordinate of the constraint, Default = [0 0 1]. y (1x3 float vector) defines the direciton of the Y-coordinate of the constraint, Default = [0 1 0]. x (3x1 float vector) internally calculated vector defining the direction of the X-coordinate for the constraint, Default = []. rotationMatrix (3x3 float matrix) internally calculated rotation matrix to go from standard coordinate orientation to the constraint coordinate orientation, Default = [].

Method Summary

checkInputs(): This method checks WEC-Sim user inputs and generates error messages if parameters are not properly defined.

setInitDisp(relCoord, axisAngleList, addLinDisp)

Function to set a constraints’s initial displacement

This function assumes that all rotations are about the same relative coordinate. If not, the user should input a relative coordinate of 0,0,0 and use the additional linear displacement parameter to set the cg or location correctly.

Parameters:

relCoord ([1 3] float vector) – Distance from x_rot to the body center of gravity or the constraint or pto location as defined by: relCoord = cg - x_rot. [m]
axisAngleList ([nAngle 4] float vector) – List of axes and angles of the rotations with the format: [n_x n_y n_z angle] (angle in rad) Rotations applied consecutively in order of dimension 1
addLinDisp ([1 3] float vector) – Initial linear displacement (in addition to the displacement caused by rotation) [m]

PTO Class

class objects.ptoClass

The ptoClass creates a pto object saved to the MATLAB workspace. The ptoClass includes properties and methods used to define PTO connections between the body motion relative to the global reference frame or relative to other bodies.

ptoClass

This method initilizes the ptoClass and creates a pto object.

Parameters:: filename (string) – String specifying the name of the pto
Returns:: pto – ptoClass object
Return type:: obj

Constructor Summary

Property Summary

damping: input file

equilibriumPosition: (float) Linear PTO equilibrium position, m or deg. Default = 0.

hardStops: (float) Define lower limit transition region, over which spring and damping values ramp up to full values. Increase for stability. m or deg. Default = 1e-4

initial: (structure) Defines the initial displacement of the pto. displacement (3x1 float vector) is defined as the initial displacement of the pto [m] in the following format [x y z], Default = [0 0 0].

extension: (string) Specify priority level for extension. `` ‘High’ or ‘Low’ `` Default = High.

location: (3x1 float vector) PTO location [m]. Defined in the following format [x y z]. Default = [999 999 999].

name: (string) Specifies the pto name. For ptos this is defined by the user, Default = NOT DEFINED.

orientation: (structure) Defines the orientation axis of the pto. z (1x3 float vector) defines the direction of the Z-coordinate of the pto, Default = [0 0 1]. y (1x3 float vector) defines the direction of the Y-coordinate of the pto, Default = [0 1 0]. x (1x3 float vector) internally calculated vector defining the direction of the X-coordinate for the pto, Default = []. rotationMatrix (3x3 float matrix) internally calculated rotation matrix to go from standard coordinate orientation to the pto coordinate orientation, Default = [].

pretension: (float) Linear PTO pretension, N or N-m. Default = 0.

stiffness: (float) Linear PTO stiffness coefficient. Default = 0.

Method Summary

checkInputs(): This method checks WEC-Sim user inputs and generates error messages if parameters are not properly defined.

setInitDisp(relCoord, axisAngleList, addLinDisp)

Function to set a pto’s initial displacement

This function assumes that all rotations are about the same relative coordinate. If not, the user should input a relative coordinate of 0,0,0 and use the additional linear displacement parameter to set the cg or location correctly.

Parameters:

relCoord ([1 3] float vector) – Distance from x_rot to the body center of gravity or the constraint or pto location as defined by: relCoord = cg - x_rot. [m]
axisAngleList ([nAngle 4] float vector) – List of axes and angles of the rotations with the format: [n_x n_y n_z angle] (angle in rad) Rotations applied consecutively in order of dimension 1
addLinDisp ([1 3] float vector) – Initial linear displacement (in addition to the displacement caused by rotation) [m]

Mooring Class

class objects.mooringClass

The mooringClass creates a mooring object saved to the MATLAB workspace. The mooringClass includes properties and methods used to define cable connections relative to other bodies. It is suggested that the mooringClass be used for connections between bodies and the global reference frame.

This class contains mooring parameters and settings

Constructor Summary

Property Summary

initial: input file

location: (1x3 float vector) Mooring Reference location. Default = [0 0 0]

matrix: (structure) Defines the mooring parameters. damping (6x6 float matrix) Matrix of damping coefficients, Default = zeros(6). stiffness (6x6 float matrix) Matrix of stiffness coefficients, Default = zeros(6). preTension (1x6 float vector) Array of pretension force in each dof, Default = [0 0 0 0 0 0].

moorDyn: (integer) Flag to indicate and initialize a MoorDyn connection, 0 or 1. Default = 0

moorDynLines: (integer) Number of lines in MoorDyn. Default = 0

moorDynNodes: (integer) number of nodes for each line. Default = 'NOT DEFINED'

name: (string) Name of the mooring. Default = 'NOT DEFINED'

moorDynInputFile: (string) Name of the MoorDyn input file path. Outputs will be written to this path. Default = Mooring/lines.txt

lookupTableFlag: (integer) Flag to indicate a mooring look-up table, 0 or 1. Default = 0

lookupTableFile: (string) Mooring look-up table file name. Default = '';

lookupTable: (array) Lookup table data. Force data in 6 DOFs indexed by displacement in 6 DOF

Method Summary

checkInputs(): This method checks WEC-Sim user inputs and generates error messages if parameters are not properly defined.

checkPath(): this method checks the moordyn path is correct for reading in outputs

setInitDisp(relCoord, axisAngleList, addLinDisp)

Function to set a mooring’s initial displacement

This function assumes that all rotations are about the same relative coordinate. If not, the user should input a relative coordinate of 0,0,0 and use the additional linear displacement parameter to set the cg or orientation correctly.

Parameters:

relCoord ([1 3] float vector) – Distance from x_rot to the body center of gravity or the constraint or pto location as defined by: relCoord = cg - x_rot. [m]
axisAngleList ([nAngle 4] float vector) – List of axes and angles of the rotations with the format: [n_x n_y n_z angle] (angle in rad) Rotations applied consecutively in order of dimension 1
addLinDisp ([1 3] float vector) – Initial linear displacement (in addition to the displacement caused by rotation) [m]

loadLookupTable(): Method to load the lookup table and assign to the mooringClass

callMoorDynLib(): Initialize MoorDyn Lib (Windows:dll or OSX:dylib)

closeMoorDynLib(): Close MoorDyn Lib

Cable Class

class objects.cableClass

The cableClass creates a cable object saved to the MATLAB workspace. The cableClass includes properties and methods used to define cable connections relative to other bodies. It is suggested that the cableClass be used for connections between joints or ptos.

cableClass

This method initilizes the cableClass and creates a cable object.

Parameters:

name (string) – String specifying the name of the cable
baseConnection (string) – Variable for the base constraint/pto as a string
followerConnection (string) – Variable for the follower constraint/pto as a string

Returns:

cable – cableClass object

Return type:

obj

Constructor Summary

Property Summary

damping: input file

inertia: (1x3 float vector) body moments of inertia kg-m^2, default [1 1 1]

inertiaProducts: (1x3 float vector) body products of inertia kg-m^2, default [0 0 0]

initial: (structure) Defines the initial displacement of the body. displacement (3x1 float vector) is defined as the initial displacement of the body center of gravity (COG) [m] in the following format [x y z], Default = [0 0 0]. axis (3x1 float vector) is defined as the axis of rotation in the following format [x y z], Default = [0 1 0]. angle (float) is defined as the initial angular displacement of the body COG [rad], Default = 0.

cableLength: (float) Cable equilibrium length (m), calculated from rotloc and preTension. Default =`0`.

linearDamping: (1x6 float vector) linear damping aplied to body motions

mass: (float) mass in kg, default 1

name: (string) Defines the Cable name. Default = NOT DEFINED.

orientation: (structure) Defines the orientation axis of the pto. z (1x3 float vector) defines the direciton of the Z-coordinate of the pto, Default = [0 0 1]. y (1x3 float vector) defines the direciton of the Y-coordinate of the pto, Default = [0 1 0]. x (1x3 float vector) internally calculated vector defining the direction of the X-coordinate for the pto, Default = []. rotationMatrix (3x3 float matrix) internally calculated rotation matrix to go from standard coordinate orientation to the pto coordinate orientation, Default = [].

paraview: (integer) Flag for visualisation in Paraview either 0 (no) or 1 (yes). Default = 1 since only called in paraview.

preTension: (float) Cable pretension (N).

quadDrag: (structure) Defines the viscous quadratic drag forces. First option define drag, (6x6 float matrix), Default = zeros(6). Second option define cd, (6x1 float vector), Default = zeros(6,1), and area, (6x1 float vector), Default = zeros(6,1).

stiffness: (float) Cable stiffness (N/m). Default = 0.

viz: (structure) Defines visualization properties in either SimScape or Paraview. color (3x1 float vector) is defined as the body visualization color, Default = [1 1 0]. opacity (integer) is defined as the body opacity, Default = 1.

base: internal

follower: (structure) Defines the follower connection. centerBuoyancy (1 x 3 float vector) center of buoyancy location of the base drag body, Default = [0 0 0]. centerGravity (1 x 3 float vector) center of gravity location of the base drag body, Default = [0 0 0]. location (3x1 float vector) base location [m], Defined in the following format [x y z], Default = []. name (string) name of the base constraint or PTO, Default = ‘NOT DEFINED’;

Method Summary

checkInputs(): This method checks WEC-Sim user inputs and generates error messages if parameters are not properly defined.

setInitDisp(relCoord, axisAngleList, addLinDisp)

Function to set a body’s initial displacement

This function assumes that all rotations are about the same relative coordinate. If not, the user should input a relative coordinate of 0,0,0 and use the additional linear displacement parameter to set the cg or location correctly.

Parameters:

relCoord ([1 3] float vector) – Distance from x_rot to the body center of gravity or the constraint or pto location as defined by: relCoord = cg - x_rot. [m]
axisAngleList ([nAngle 4] float vector) – List of axes and angles of the rotations with the format: [n_x n_y n_z angle] (angle in rad) Rotations applied consecutively in order of dimension 1
addLinDisp ([1 3] float vector) – Initial linear displacement (in addition to the displacement caused by rotation) [m]

setCg(): This method specifies the Cg of the drag bodies as coincident with the fixed ends of the cable, if not otherwise specied.

Response Class

class objects.responseClass

The responseClass creates an output object saved to the MATLAB workspace that contains structures for each instance of a WEC-Sim class (e.g. waveClass, bodyClass, constraintClass, ptoClass, cableClass, mooringClass, etc).

responseClass

This method initializes the responseClass, reads output from each instance of a WEC-Sim class (e.g. waveClass, bodyClass, ptoClass, mooringClass, etc) and saves the response to an output object.

Returns:: output – responseClass object
Return type:: obj

wave

This property contains a structure for each instance of the waveClass

type (string) = ‘waveType’
time (array) = [# of time-steps x 1]
elevation (array) = [# of time-steps x 1]
waveGauge1Elevation (array) = [# of time-steps x 1] Wave elevation at the location of wave gauge 1
waveGauge2Elevation (array) = [# of time-steps x 1] Wave elevation at the location of wave gauge 2
waveGauge3Elevation (array) = [# of time-steps x 1] Wave elevation at the location of wave gauge 3

bodies

This property contains a structure for each instance of the bodyClass (i.e. for each Body block)

name (string) = ‘bodyName’
time (array) = [# of time-steps x 1]
position (array) = [# of time-steps x 6]
velocity (array) = [# of time-steps x 6]
acceleration (array) = [# of time-steps x 6]
forceTotal (array) = [# of time-steps x 6] The sum of all hydrodynamic forces applied to the body
forceExcitation (array) = [# of time-steps x 6] The sum of the Froude-Krylov excitation force and the mean drift force exerted by the incoming wave on the body
forceRadiationDamping (array) = [# of time-steps x 6] The negative radiation damping force due to body velocity
forceAddedMass (array) = [# of time-steps x 6] The negative added mass force due to body acceleration
forceRestoring (array) = [# of time-steps x 6] The negative sum of the gravity force, buoyant force, the hydrostatic stiffness force, and any moment due to separation between the center of gravity and the center of buoyancy
forceMorisonAndViscous (array) = [# of time-steps x 6] The negative sum of the Morison element force and the viscous drag force
forceLinearDamping (array) = [# of time-steps x 6] The negative force due to linear damping and the body velocity

There are 4 additional output.bodies arrays when using nonlinear hydro and Paraview output:

cellPressures_time (array) = [# of Paraview time-steps x 1] Nonlinear calculation timeseries
cellPressures_hydrostatic (array) = [# of Paraview time-steps x # of mesh faces] Hydrostatic pressure on each stl facet
cellPressures_waveLinear (array) = [# of Paraview time-steps x # of mesh faces] Excitation pressure on each stl facet given zero displacement and the mean free surface
cellPressures_waveNonLinear (array) = [# of Paraview time-steps x # of mesh faces] Excitation pressure on each stl facet given the instantaneous displacement and instantaneous free surface

constraints

This property contains a structure for each instance of the constraintClass (i.e. for each Constraint block). Constraint motion is relative from frame F to frame B. Constraint forces act on frame F.

name (string) = ‘constraintName’
time (array) = [# of time-steps x 1]
position (array) = [# of time-steps x 6] The constraint position relative to the initial condition
velocity (array) = [# of time-steps x 6] The constraint velocity relative to the initial condition
acceleration (array) = [# of time-steps x 6] The constraint acceleration relative to the initial condition
forceConstraint (array) = [# of time-steps x 6] The force required to resist motion in the restricted DOFs

ptos

This property contains a structure for each instance of the ptoClass (i.e. for each PTO block). PTO motion is relative from frame F to frame B. PTO forces act on frame F.

name (string) = ‘ptoName’
time (array) = [# of time-steps x 1]
position (array) = [# of time-steps x 6] The constraint position relative to the initial condition
velocity (array) = [# of time-steps x 6] The constraint velocity relative to the initial condition
acceleration (array) = [# of time-steps x 6] The constraint acceleration relative to the initial condition
forceTotal (array) = [# of time-steps x 6] The sum of the actuation, constraint and internal mechanics forces
forceActuation (array) = [# of time-steps x 6] The prescribed force input to the PTO to control its motion
forceConstraint (array) = [# of time-steps x 6] The force required to resist motion in the restricted DOFs
forceInternalMechanics (array) = [# of time-steps x 6] The net force in the joint DOF due to stiffness and damping
powerInternalMechanics (array) = [# of time-steps x 6] The net power lost in the joint DOF due to stiffness and damping

cables

This property contains a structure for each instance of the cableClass (i.e. for each Cable block)

name (string) = ‘cableName’
time (array) = [# of time-steps x 1]
position (array) = [# of time-steps x 6]
velocity (array) = [# of time-steps x 6]
acceleration (array) = [# of time-steps x 6]
forceTotal (array) = [# of time-steps x 6] The sum of the actuation and constraint forces
forceActuation (array) = [# of time-steps x 6] The cable tension
forceConstraint (array) = [# of time-steps x 6] The force required to resist motion in the restricted DOFs

mooring

This property contains a structure for each instance of the mooringClass using the mooring matrix (i.e. for each MooringMatrix block)

position (array) = [# of time-steps x 6]
velocity (array) = [# of time-steps x 6]
forceMooring (array) = [# of time-steps x 6] The sum of the stiffness, damping and pretension forces applied on the body by the mooring

moorDyn

This property contains a structure for each instance of the mooringClass using MoorDyn (i.e. for each MoorDyn block)

Lines (struct) = [1 x 1] Contains the time and fairlead tensions
Line# (struct) = [1 x 1] One structure for each mooring line: Line1, Line2, etc. Each line structure contains node positions in x, y, z and segment tensions

ptoSim

This property contains a structure for each instance of the ptoSimClass (i.e. for each PTO-Sim block).

time (struct) = [# of time-steps x 1] Simulation timeseries

There are additional output.ptoSim structs corresponding to the Simulink blocks used:

pistonCF (struct) = [1 x # of pistons] Structure containing timeseries of compressible fluid piston properties including absolute power, force, position, velocity

pistonNCF (array) = [1 x # of pistons] Structure containing timeseries of non-compressible fluid piston properties including absolute power, force, top pressure and bottom pressure

checkValve (struct) = [1 x # of valves] Structure containing timeseries of check valve properies including volume flow rate

valve (struct) = [1 x # of valves] Structure containing timeseries of valve properties including volume flow rate

accumulator (struct) = [1 x # of accumulators] Structure containing timeseries of accumulator properties including pressure and volume

hydraulicMotor (struct) = [1 x # of motors] Structure containing timeseries of hydraulic motor properties including angular velocity and volume flow rate

rotaryGenerator (struct) = [1 x # of generators] Structure containing timeseries of rotary generator properties including electrical power and generated power

simpleDD (struct) = [1 x # of generators] Structure containing timeseries of direct drive PTO properties including forces and electrical power

pmLinearGenerator (struct) = [1 x # of generators] Structure containing timeseries of permanent magnet linear generator properties including absolute power, force, friction force, current, voltage, velocity and electrical power

pmRotaryGenerator (struct) = [1 x # of generators] Structure containing timeseries of permanent magnet rotary generator properties including absolute power, force, friction force, current, voltage, velocity and electrical power

motionMechanism (struct) = [1 x # of mechanisms] Structure containing timeseries of motion mechanism properties including PTO torque, angular position and angular velocity

windTurbine

This property contains a structure for each instance of the windTurbineClass

name (string) = ‘windTurbineName’
time (array) = [# of time-steps x 1]
windSpeed (array) = [# of time-steps x 1]
turbinePower (array) = [# of time-steps x 1]
rotorSpeed (array) = [# of time-steps x 1]
bladePitch (array) = [# of time-steps x 1] Pitch position of blade 1
nacelleAcceleration (array) = [# of time-steps x 1]
towerBaseLoad (array) = [# of time-steps x 6] 6DOF force at the constraint between the floating body and tower base
towerTopLoad (array) = [# of time-steps x 6] 6DOF force at the constraint between the tower base and tower nacelle
bladeRootLoad (array) = [# of time-steps x 1] 6DOF force at the constraint between blade 1 and the hub
genTorque (array) = [# of time-steps x 1] Torque on the generator
azimuth (array) = [# of time-steps x 1] azimuthal angle of the generator

Constructor Summary

Property Summary

ptoSim: This property contains a structure for each instance of the ptoSimClass (i.e. for each PTO-Sim block).

windTurbine: This property contains a structure for each instance of the windTurbineClass

Method Summary

plotResponse(bodyNum, comp)

This method plots the response of a body for a given DOF.

Parameters:

bodyNum (integer) – the body number to plot
comp (integer) – the response component (i.e. dof) to be plotted (e.g. 1-6)

plotForces(bodyNum, comp)

This method plots the forces on a body for a given DOF.

Parameters:

bodyNum (integer) – the body number to plot
comp (integer) – the force component (i.e. dof) to be plotted (e.g. 1-6)

saveViz(simu, body, waves, options)

This method plots and saves the wave elevation and body geometry over time to visualize the waves and response

Parameters:

simu – simulationClass object
body – bodyClass object
waves – waveClass object
options –

axisLimits1x6 float matrix
x, y, and z-bounds of figure axes in the format: [min x, max x, min y, max y, min z, max z] Default = [-simu.domainSize/2 simu.domainSize/2 -simu.domainSize/2 simu.domainSize/2 -waves.waterDepth maximumHeight]

timesPerFramefloat
number of simulation time steps per video frame (higher number decreases computation time) Default = 1

startEndTime1x2 float matrix
Array defining the start and end times of the visualization Default = [min(t) max(t)]

saveSettinginteger
0 = video, 1 = gif. Default = 0

writeText(): This method writes WEC-Sim outputs to a (ASCII) text file. This method is executed by specifying simu.outputtxt=1 in the wecSimInputFile.m.