Define invariant variables

While in the Model Writing role, you can identify variables as invariant variables. Invariant variables do not change values or badging when you revert the simulation to a snapshot that you captured. This applies to both Model Writers and Simulation Builders.

Typically, variables that do not change with operating conditions are good candidates for invariant variables. For example, the length of a pipe does not change with operating conditions. You may want to define the length of a pipe as an invariant variable. Conversely, the flow through a pipe and the pressure in the pipe depend on operating conditions and should not be invariant variables.

The Solver changes the values of calculated variables even if you identify them as invariant variables. If a Model Type has connections that use an invariant variable, AVEVA Process Simulation treats all variables in the connection as invariant variables.

Define a variable as an invariant variable

1. Ensure that the Model Writing role is selected. See Roles, Roles.

2. Load the Model Editor for the desired Model Type.

3. Expand the Variables section.

4. Select the Invariant icon to flag the variable as an invariant variable.