Defining Expressions for Non-Transient Solutions
You can specify additional convergence criteria through the use of expressions and output variables. The Maximum Delta or the Maximum Percent Delta defined for expression convergence represents the difference in values of the expressions between consecutive adaptive passes. If the difference in the value of the expression between consecutive passes is less than the Maximum Delta or the Maximum Percent Delta value this part of the convergence criteria is satisfied.
To set expressions as convergence criteria:
- Right-click on the Analysis icon in the Project Manager tree to open the Solution Setup dialog box.
- Click the Expression Cache tab and click the Add... button to open the Add to Expression Cache dialog box.
- Specify the Context for the expression, including Report Type, Solution, Parameter.
- Under the Trace tab, select from the Category, Quantity, and Function lists to create expressions.
- When finished defining the expression that you want to add to the cache, click the Add Calculation button.
- When finished adding expressions, click Done to close the Add to Expression Cache dialog box.
- The Title field is editable, by default showing the name as built from the expression (with underscores removed).
- The Expression field shows the full expression. If necessary, you can resize the Solution Setup dialog box. You can also resize each columns in the table.
- The Context column shows None for Modal solutions, or the appropriate geometry for Fields calculations.
- The Intrinsics column shows a clickable button that opens an Edit Calculation Range dialog box. If the Intrinsics column button shows None you cannot edit the value. If the button shows variables, click the ellipsis [...] in the Edit column to display a list of the variable values from which you can select. Click OK to close the Edit Calculation Range dialog box and apply your selections to the Expression Cache.
- To designate one or more expressions for convergence, click the field for the Convergence column for each expression.
- Optionally, buttons allow you to Edit and Remove selected expressions, and to Remove All expressions in the table.
- For Eddy Current only check boxes allow you to save the expression cache either with Evaluate Cache vs. Pass, Evaluate Cache vs. Freq, or both.
- When finished defining expressions, click OK to close the Solution Setup dialog box.
Selecting a listed category lists the Quantities and Functions available for each category. If you have defined one or more output variables, you can see them by selecting the Output Variables category. The Output Variables button opens a dialog box that lets you define output variables. See Specifying Output Variables.
When you have created an expression, it appears in the Expression field of the Trace tab. If desired, you can use the Range Function button to select range functions to apply to the expression.
Under the Calculation Range tab, you can view the values of available sweep variables. Clicking the ellipsis [...] button in the Edit column opens a list of values from which you can select.
This adds the selected expression and the associated context to a table in the Expression Cache tab. You can define additional expressions with contexts and add them in the same way.
The Expression Cache tab lists the expressions you have added in a table.
This opens an Adaptive Convergence dialog box. Check Use this expression for convergence to enable the radio buttons. You can then specify the Maximum Delta (an absolute change in value between passes) or the Maximum Percent Delta (a percentage change in value between passes) criteria. The Maximum Delta provides a way around a potential issue if your expression is essentially zero and the numeric noise from pass to pass causes the maximum percentage delta to remain high. In that case adaptive refinement continues until you get to the maximum number of passes.