model.reduced()
Reduced-order modeling.
There are reduced-order models of different types. The properties listed below are set and accessed using generic set and get methods described in set() and get* and Selection Access Methods. The following reduced-order model types are currently supported:
Table 2-118: Reduced-order Model Types.
Type
Description
ModalFrequency
Created by the Model Reduction study step for a parametric problem using the modal solver.
ModalTransient
Created by the Model Reduction study for a time-dependent problem using the modal solver.
PODFrequency
Created by the Model Reduction study step for a frequency-dependent problem using POD reduction.
PODTransient
Created by the Model Reduction study for a time-dependent problem using POD reduction.
AWE
Created by the Model Reduction study step for a parametric problem using the asymptotic waveform evaluation (AWE) solver.
RandomVibration
Uses a Frequency-Domain, Modal Reduced-Order Model to compute model response to random excitations.
Syntax
model.reduced()
model.reduced().create(<tag>, <type>);
 
model.reduced().getM(String)
model.reduced().getN(String)
model.reduced().getNnz(String)
model.reduced().getOutputs()
model.reduced().getParameters()
model.reduced().getSparseMatrixCol(String)
model.reduced().getSparseMatrixRow(String)
model.reduced().getSparseMatrixVal(String)
model.reduced().getSparseMatrixValImag(String)
model.reduced().getVector(String)
model.reduced().getVectorImag(String)
model.reduced().isReal(String)
description
model.reduced().create(<tag>,<type>) creates a reduced-model container of the specified type.
Depending on the type of reduced-order model, the following properties are available:
Table 2-119: Properties For Reduced-Order model Types.
NAME
VALUE
DEFAULT
DESCRIPTION
Read Only
depvars
boolean
false
Controls if models with output variables should define degrees of freedom.
 
depvarnames
String array
{}
Names of dependent variables.
 
information
String
Empty
Model information.
√
logMessage
String
Empty
The Build log.
√
matrices
String matrix
{{}}
Names and descriptions of matrices.
√
metaCOMSOLVersion
String
Empty
String description of the COMSOL version when the model has been created.
√
metaCOMSOLVersionInt
String
Empty
Numerical representation of the COMSOL version when the model has been created.
√
outputDescr
String array
{}
Descriptions of output variables.
√
outputExprs
String array
{}
Values or expressions of output variables.
√
outputNames
String array
{}
Names of output variables.
√
reconstructors
String array
{}
Names of reconstruction variables.
√
reconstructorDescr
String array
{}
Descriptions of reconstruction variables.
√
vectors
String matrix
{{}}
Names and descriptions of vectors.
√
Note that only metaCOMSOLVersion and metaCOMSOLVersionInt are defined for the RandomVibration reduced-order model..
Table 2-120: Properties For the ModalFrequency Reduced-Order model.
NAME
VALUE
DEFAULT
DESCRIPTION
Read Only
constrStateDescrs
String array
Constraint mode Y, where "Y" represents the index of the constraint mode among all constraint modes
Description of the Constraint mode.
Read only in the stateless case; editable in the stateful case.
constrStateExprs
String array
{"0"}
Constraint expression. This is the Model Control Input expression if one was found. Else this expression is 0 per default.
If the constraint variable is mapped to an input, then its expression is read only.
constrStateNames
String array
romX.constrStateY, where "Y" represents the index of the constraint mode among all constraint modes
Constraint DOF variable name (alias). This variable will evaluate to the ROM operator rom1.state(X), with X being the internal state DOF number.
√
constrStateModesIndices
String array
{}
The actual mode index of constraint modes among all modes.
√
constrStateUsed
String array
{"off"}
Flag for enabling and disabling constraints for the constraint variables.
 
controls
String array
{}
Values or expressions of control variables.
 
controlDescr
String array
{}
Descriptions of control variables.
√
controlNames
String array
{}
Names of control variables.
√
dampingRatio
String
"0"
Damping ratio used by Uniform damping.
 
dampingRatioPerMode
String array
{"0"}
Damping ratio for each eigenmode.
 
form
Automatic | Frequency
Automatic
Equation form (when interf is stateful): study controlled (Automatic) or frequency domain (Frequency).
 
freq
String
freq
Value or expression for the frequency, when freq_src is userdef or interf is stateless.
 
freq_src
fromSolver | userdef
fromSolver
Frequency source: from the solver or a user-defined frequency, when form is Frequency.
 
interf
stateful | stateless
stateless
Use a stateless or stateful interface.
 
loadfact
String
1
Load factor value or expression.
 
matrices
String matrix
{{"Kr", "Stiffness matrix"},
{"Kr_c", "Constrained part of stiffness matrix"},
{"Dr", "Damping matrix"}, {"Dr_c", "Constrained part of damping matrix"},
{"Dra", "Damping ratio matrix"}, {"Dra_c", "Constrained part of damping ratio matrix"},
{"Er", "Mass matrix"}, {"Er_c", "Constrained part of mass matrix"},
{"Br", "Input matrix"},
{"Cr", "Output matrix"},
{"F", "Input feedback matrix"}}
Names and descriptions of matrices.
√
modalfrequencies
String array
 
Frequency for each eigenmode.
√
modalDamping
String
noDamping
Damping of Modal reduced-order model.
 
phase
String
phase
Phase value or expression, when interf is stateless. If given, the reconstructed solution will be multiplied by the factor exp(i*phase) prior to expression evaluation with the <rom>.eval(<expr>) operator.
 
solveElimSystem
boolean
false
Solve an eliminated system with constraints from constrain modes being removed, when interf is set to stateful.
 
vectors
String matrix
{{"L", "Load vector"},
{"Y0", "Output bias"},
{"EPartSol", "Mass matrix times particular solution"},
{"DPartSol", "Damping matrix times particular solution"}},
{"CImap", "Constraint modes to inputs map"}
Names and descriptions of vectors.
√
Table 2-121: Properties For the ModalTransient Reduced-Order model.
NAME
VALUE
DEFAULT
DESCRIPTION
Read Only
constrStateDescrs
String array
Constraint mode Y, where "Y" represents the index of the constraint mode among all constraint modes
Description of the Constraint mode.
Read only in the stateless case; editable in the stateful case.
constrStateExprs
String array
{"0"}
Constraint expression. This is the Model Control Input expression if one was found. Else this expression is 0 per default.
If the constraint variable is mapped to an input, then its expression is read only.
constrStateNames
String array
romX.constrStateY, where "Y" represents the index of the constraint mode among all constraint modes
Constraint DOF variable name (alias). This variable will evaluate to the ROM operator rom1.state(X), with X being the internal state DOF number.
√
constrStateModesIndices
String array
{}
The actual mode index of constraint modes among all modes.
√
constrStateUsed
String array
{"off"}
Flag for enabling and disabling constraints for the constraint variables.
 
controls
String array
{}
Values or expressions of control variables.
 
controlDescr
String array
{}
Descriptions of control variables.
√
controlNames
String array
{}
Names of control variables.
√
dampingRatio
String
0
Damping ratio used by Uniform damping.
 
dampingRatioPerMode
String array
{0}
Damping ratio for each eigenmode.
 
form
Automatic | Transient
Automatic
Equation form (when interf is stateful): study controlled (Automatic) or time domain (Transient).
 
interf
stateful | stateless
stateless
Use a stateless or stateful interface.
 
loadfact
String
"1"
Load factor value or expression.
 
matrices
String matrix
{{"Kr","Stiffness matrix"},
{"Kr_c", "Constrained part of stiffness matrix"},
{"Kr", "Stiffness matrix"},
{"Dr", "Damping matrix"},
{"Dr_c", "Constrained part of damping matrix"},
{"Dra", "Damping ratio matrix"},
{"Dra_c", "Constrained part of damping ratio matrix"},
{"Er", "Mass matrix"},
{"Er_c", "Constrained part of mass matrix"},
{"Br", "Input matrix"},
{"Cr", "Output matrix"},
{"F", "Input feedback matrix"},
{"B0r","Initial value input matrix"},
{"B0rdot", "Initial value time derivative input matrix"},
{"Brdot", "Time derivative input matrix"},
{"Brdotdot", "Second time derivative input matrix"},
{"Mc", "Mass matrix"}, {"Mc_c", "Constrained part of mass matrix"},
Names and descriptions of matrices.
√
matrices
 
{"MA", "Stiffness matrix"},
{"MA_c", "Constrained part of stiffness matrix"},
{"MB", "Input matrix"},
{"D", "Input feedback matrix"},
{"C", "Output matrix"},
{"C_c", "Constrained part of output matrix"}}
Continued from the previous page.
√
modalfrequencies
String array
 
Frequency for each eigenmode.
√
modalDamping
String
noDamping
Damping of Modal reduced-order model.
 
rtol
double
0.01
Relative tolerance.
 
solveElimSystem
boolean
false
Solve an eliminated system with constraints from constrain modes being removed, when interf is set to stateful.
 
time
String
t
Value or expression for the time, when interf is stateless.
 
vectors
String matrix
{{"L","Load vector"},
{"Y0", "Output bias"},
{"U0","Output bias"},
{"Udot0","Initial derivative vector"},
{"Kud","Stiffness matrix times ud"},
{"x0","Initial value vector"}},
{"CImap", "Constraint modes to inputs map"}
Names and descriptions of vectors.
√
Table 2-122: Properties For the AWE Reduced-Order model.
NAME
VALUE
DEFAULT
DESCRIPTION
Read Only
freq
String
freq
Value or expression for the frequency.
 
phase
String
phase
Phase value or expression. If given, the reconstructed solution will be multiplied by the factor exp(i*phase) prior to expression evaluation with the <rom>.eval(<expr>) operator.
 
Table 2-123: Properties for the Random Vibration Model.
NAME
VALUE
DEFAULT
DESCRIPTION
correlationMatrix
upper-triangle of a matrix
all 0s
The correlation matrix, when correlationType is crossCorrelated.
correlationType
uncorrelated | fullyCorrelated | crossCorrelated
uncorrelated
The correlation type.
fHigh
positive double
1000
Upper frequency limit as an integration bound.
fLow
positive double
1
Lower frequency limit as an integration bound.
frequencyResponseModel
name of frequency-domain, modal reduced-order model
 
The frequency response model to use. Specify its components using the setIndex method.
integrationMethod
automatic | userDefined
automatic
Use an automatic or user-defined integration method.
integrationPoints
integer > 1
1001
Number of integration points, if integrationMethod is set to userDefined.
powerSpectralDensity
double scalar vector
all 0s
The power spectral density for each control name. Specify each power spectral density using the setIndex method.
For information about the getM, getN, getNnz, isReal, and the getSparseMatrix and getVector methods, see the matrix data tables Table 6-6 and Table 6-7 in the Solvers and Study Steps chapter.
Compatibility
The constrStateMap property has been removed in version 6.3.
The parameters property is deprecated in version 6.1 and has been replaced by the freq or time property. It may be removed in future versions, but until then, for backward compatibility, changing the parameters property automatically triggers a corresponding change of freq or time (but not the other way around).
The following methods are deprecated in version 5.5 and may be removed in future versions:
getOutputs()
getControls()
getParameters()
getValues(String[])
getVectors()
getMatrices()
getDescription(String[])
getString(String)
setControl(String, String)
The following methods are not supported:
create(<tag>)
create(<tag>, filepath)
setParameter(String, String)
renameControl(String, String)
renameOutput(String, String)