Boundary condition ID in expressions

When you create streams, voids, and convecting zones, the software assigns a numerical ID to the boundary condition. Certain thermal-flow functions in the CAE expression system use this numerical ID as their argument.

To change the numerical ID of these boundary conditions, you can do one of the following:

• In the dialog box for the boundary condition, edit the numerical ID.

• Use the Boundary Condition ID Manager command.

When you change the boundary condition ID number, the software automatically updates all the formulas for expressions that contain the numerical ID to reflect the new ID number.

For example, suppose a model contains a stream whose numerical ID is 23 and an expression whose formula contains STO(23). If you change the numerical ID of the stream to 35, the software automatically changes STO(23) to STO(35) in the formula for the expression.

With the Boundary Condition ID Manager command, you have two options for changing ID numbers:

• Renumber

• Offset

The following example shows how these options differ.

Suppose that you want to change the ID numbers for four streams in your model. The ID numbers for these streams are 1, 2, 3, and 4. However, the order that they are listed in the Selected Boundary Conditions table or entered in the List of Indices box is 3, 1, 4, 2.

If you select the Renumber option, and enter 11 in the From box, the stream ID numbers change as follows:

• Stream 3 → Stream 11

• Stream 1 → Stream 12

• Stream 4 → Stream 13

• Stream 2 → Stream 14

If you select the Offset option, and enter 11 in the By box, the stream ID numbers change as follows:

• Stream 3 → Stream 14

• Stream 1 → Stream 12

• Stream 4 → Stream 15

• Stream 2 → Stream 13

For a given type boundary condition, the ID numbers must be unique. However, boundary condition of different types can share the same ID number.

For example, a stream and a void can both have an ID number of 5.

For such a case, when you change the ID number of one of the boundary conditions, the ID number of the other boundary condition does not change.

For example, if you change the ID number of the stream from 5 to 10, the ID number of the void remains 5.

Where do I find it?

Application	Pre/Post
Prerequisite	A Simulation file as the work part and displayed part
Command Finder	Boundary Condition ID Manager

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