8/24/2011

Introduction to CFX -CFX Expression Language

CEL

CEL - CFX Expression Language

-Allows the user to create equations (can be functions of solution/system variables) that can be used in CFX-Pre and CFD-Post

CEL Rules

The syntax rules are the same as those for conventional arithmetic. Operators are written as:

Variables and expressions are case sensitive (example: t vs. T)

Expressions must be dimensionally consistent for addition and subtraction operations (example: 1.0 [mm] + 0.45 [yds] is OK)

-You cannot add values with inconsistent dimensions

Built In Functions

Numerical functions and operators are also available in CEL

-Right-click when creating expressions for a complete list

-Custom functions with User Fortran can also be created

Solver Variables

Solver variables are available for use in any expression

Below is a partial list of the available system variables:

-When creating expressions, right-click to access a full list

How To Create Expressions

CEL in CFX-Pre: Example 1

Creating a variable viscosity

-Viscosity of a shear thickening fluid:

Alternatively, an expression can be entered directly into a field

CEL in CFX-Pre: Example 2

Using an “if” Function

-Set inlet temperature to 300 K for the first 19 iterations then raise it to 320 K after 20 iterations

User Functions

You can also define your own 1-D linear, or 3-D cloud of points interpolation functions

http://www.cadfamily.com/HTML/Article/Introduction%20to%20CFX%20-CFX%20Expression%20Language_773_1.htm

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