COMSOL 6.3 - Model Reduction

Model Reduction

Use a Model Reduction study step to perform simulations with reduced models or to produce reduced models.

A Model reduction study step will involve the following settings

Selecting the model reduction method to apply.

If applicable: Selecting the training data (Select or generate Study and Study step reference).

Defining the unreduced (source) model (Study and Study step reference).

If applicable: Defining the objective function representing a quality measure to minimize.

Selecting to create or update an instance of the reduced model under reduced models for online use.

If applicable: Specifying if the reduced model should be capable of reconstruction.

Defining reduced-model control inputs.

Defining reduced-model outputs.

Syntax

model.study(stdname).create(fname,"ModelReduction");

model.study(stdname).feature(fname).set(pname,value);

Description

Study step for model reduction. The following general and common properties are available.

Table 6-142: General and Common Properties For Model Reduction.
Property	Value	Default	Description
awefunc	String array		Error expressions, if reducedModelType is awe.
awefuncdesc	String array		Description of the error variables, if reducedModelType is awe.
awefuncscale	String array		Scale of the error variables, if reducedModelType is awe.
awefuncunit	String array		Unit of the error functions, if reducedModelType is awe.
awefuncuse	String array		Error expressions, if reducedModelType is awe.
awevar	String array		Model error/output variables, if reducedModelType is awe.
initval	String array		Values for the model control inputs used for the simulation using the modal solver, if reducedModelType is modal.
reducedModelType	modal \| awe \| pod	modal	Model reduction method to use.
romdata	String	new	Tag of the target container for the reduced model (new for a new reduced model).
romReconstruct	true \| false	true	Enable reconstruction in the produced reduced model.
pname	String array		Model parameter names to use as model control input variables, if reducedModelType is modal.
podtrainingsol	String		Solution selection, if reducedModelType is pod.
qoidescr	String array		Descriptions for user-defined output expressions, if reducedModelType is modal.
qoiexpr	String array		Global expressions defining outputs, if reducedModelType is modal.
qoiname	String array		Variable names for outputs, if reducedModelType is modal.
qoiunit	String array		Units for user-defined output expressions, if reducedModelType is modal.
rtol	double	0.1	Relative tolerance for adaptation, if reducedModelType is awe
soltypemat	true \| false	false	Store reduced matrices in the modal solver solution, if reducedModelType is modal.
soltypeonline	on \| off	on	Create a reduced model.
trainingStepConstr	String (auto or none)	auto	Study step for constraint modes, if reducedModelType is pod.
trainingStudyConstr	String	none	Training study for constraint modes, if reducedModelType is pod.
truncationrtol	double	0.01	The relative truncation tolerance, if reducedModelType is awe or pod.
unreducedModelStepAWE	String	none	Frequency domain study step, if reducedModelType is awe.
unreducedModelStepPOD	String	none	Frequency domain study step, if reducedModelType is pod.
unreducedModelStudyAWE	String	none	Study containing at least one compatible study step, if reducedModelType is awe.
unreducedModelStudyPOD	String	none	Study containing at least one compatible study step, if reducedModelType is pod.
useExtraResultsCompileEquations	true \| false	false	Use extra Compile Equations for Results.

For the modal model reduction method, the following methods are available.

Table 6-143: Properties for Modal Model Reduction.
Property	Value	Default	Description
trainingStep	String (auto or none)	auto	Study step compatible with the chosen model reduction method used to produce the basis of the reduced method.
trainingStudy	String	none	Study containing a study step compatible with training data for the chosen method.
unreducedModelStep	String	none	Study step compatible with the chosen model reduction method used to define the model to reduced.
unreducedModelStudy	String	none	Study containing a study step for reduction compatible with the chosen method.

The following properties are available for a time-dependent unreduced study (an unreducedModelStep).

Table 6-144: Properties For a Time-Dependent Unreduced Study.
Property	Value	Default	Description
romSolveTransient	on \| off	off	Reduced-model simulation using the modal solver.
tlist	double array	range(0,0.1,1)	Time list for the simulation with the modal solver.

The following properties are available for a frequency-dependent unreduced study (an unreducedModelStep).

Table 6-145: Properties For a Frequency-Dependent Unreduced Study.
Property	Value	Default	Description
romSolveFrequency	on \| off	off	Reduced-model simulation using the modal solver.
plist	double array		Frequency list for the simulation with the modal solver. The first frequency is used as the linearization frequency for the second-order expansion of the matrices.