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Understanding design variables
A design variable is a simulation entity of your model that the TMG Correlation solver varies within a specific range during the optimization to reduce the gap between the reference data and the simulation results.
Create design variables
The following example shows how to create design variables from a parameter using the multiplier method for the thermal correlation analysis.

User help
- Introduction to TMG Correlation
- TMG Correlation workflow
- TMG Correlation interface
  The TMG Correlation user interface is integrated in Simcenter 3D using NX Open and contains unique features to conduct a thermal correlation analysis, in addition to standard tools and commands described in the Simcenter 3D Online help and the NX Online help.
- Thermal correlation analysis preparation
  Before conducting a thermal correlation analysis, it is important to properly prepare your simulation model and the reference data.
- Understanding thermal correlation analysis
  The thermal correlation is a calibration process that helps you find the best thermal solution that minimizes the error between the computed and target temperatures at different locations and times.
- Managing the reference data
  In TMG Correlation, reference data refers to the temperature and time data that come from experimental tests or from prior and validated simulation models. They are named sensors and are used as targets for the optimization of the correlated solution.
- Understanding design variables
  A design variable is a simulation entity of your model that the TMG Correlation solver varies within a specific range during the optimization to reduce the gap between the reference data and the simulation results.
  - Create design variables
    The following example shows how to create design variables from a parameter using the multiplier method for the thermal correlation analysis.
  - Display design variable information
    Use the following procedure to display summaries information for one or more design variables created for a thermal correlation analysis.
  - Design Variables page
    The Design Variables page displays the number of design variables in the thermal correlation analysis when you select the Design Variables node in the main panel. This page automatically updates when you make changes in the Definition page.
  - Definition page
    The Definition page displays the parameters and expressions of the correlated solution from which you can create design variables for the thermal correlation analysis when you select the Definition node in the main panel.
- Setting up the optimization
  In optimization, the goal is to find values for the design variables that minimize the difference between the reference data and the correlated solution results.
- Monitoring the optimization
  Use the Solution Monitor and Solution Control Monitor to track the analysis during the solve. The monitors provide solver-specific information for the TMG thermal solver and the thermal correlation analysis.
- Analyzing the optimization results
  After you solve a thermal correlation analysis, you can analyze the results of the optimization process in the TMG Correlation dialog box.
- Updating the simulation model
  After you verified the optimization results, you must update the simulation model to reflect any changes that were made during the thermal correlation analysis so that you can continue your modeling in Simcenter 3D.
- Theory
- Legal notice
- License agreement

Create design variables

The following example shows how to create design variables from a parameter using the multiplier method for the thermal correlation analysis.

In the TMG Correlation dialog box, select the Design Variables→Definition node.
In the Parameters and Expressions group, from the Type list, select Parameters.
From the Parameter and Expression table, select a parameter you want as a design variable.

Tip:
You can use the filtering options for easier selection.
In the Design Variable Definition group, in the Design Variable Name box, type design_variable_1.
From the Design Variable Method list, select Multiplier to multiply the parameter by a design variable.
Click Add Design Variable to add the design variable to the active thermal correlation analysis.
Repeat steps 2-6 to define as many design variables as you need for the thermal correlation analysis.

The design variables listed in the Design Variables group are available for optimization and listed on the Optimization Design Variables page where you set their initial, minimum, and maximum values.