Domains

CAE expressions have an independent domain and a dependent domain.

Independent domain

The independent domain of an expression is the set of variables that are included in the formula for an expression. For example, suppose you create the following formula for an expression:

2*(x/1[mm])*(y/1[mm])

In the formula, the variables x and y constitute the independent domain, and the expression represents a functional relationship of the form:

f = f(x,y)

Expressions can reference fields and other expressions. When they do, the independent domain of the expression consists of both the variables that you enter explicitly in the formula for the expression and the variables that the referenced fields and other expressions define implicitly.

The independent domain of an expression can consist of spatial variables only, or non-spatial variables only, or a combination of spatial and non-spatial variables. Unlike fields, there is no limit to the number of non-spatial variables that you can use in combination with a set of spatial variables.

Dependent domain

The dependent domain of an expression is limited to a single quantity. This is different from fields where the dependent domain can be, for example, a set of force components.

When you create a system-defined expression, the context of the application defines the dependent domain implicitly. For example, if you use an expression to define how pressure varies over a surface, the software defines pressure as the dependent domain.

For user-defined expressions, you must define the dependent domain explicitly. You choose a dependent domain option in the Expressions dialog box when you create the expression. If you want the software to interpret the expression as dimensionless, select Unitless.

How do I

Create a user-defined expression

Create a system-defined expression

Create an expression for a measurement

Replace an expression in a formula

Test an expression

Generate a contour plot of an expression

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Expressions

System-defined and user-defined expressions

Case sensitivity in expressions

Using expressions to define boundary conditions

Finding where expressions are used

Boundary condition ID in expressions

Using unit normal vector components as variables in expressions

Special consideration when importing expressions

Specifying the default value for variables and plug-in functions

Generating a contour plot of an expression

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Example of an expression

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