[squar_o]

I am using ANSYS Windmodeller for ANSYS CFX 18.0. This uses .pre files written in CEL to set up the physics.

I am making modifications to a .pre file as below:

original working .pre file:

LIBRARY:
  CEL:
    EXPRESSIONS:
        DX = exp(-0.5* (3.5*(RXdir-RD)/WDH) ^2) [kg m^-3 s^-1])

modified to include conditional:

LIBRARY:
  CEL:
    EXPRESSIONS:
        DX = exp(-0.5* (3.5*(RXdir-RD)/WDH) ^2) [kg m^-3 s^-1])
	    if( x>0, DX = DX, DX = 0 )

As far as I can see from the CFX docs this follows the conventions of an if statement: if( cond_expr, true_expr, false_expr ). But I get the following error:

ERROR – CCL parser failed with message:
Invalid parameter name “if(x>0, DX” : contains invalid character ‘(‘

the same '(' are used in other parts of the .pre file so I am unsure of what is causing the problem

[ghorrocks]

You are not using the if statement correctly. Try this:

temp = exp(-0.5* (3.5*(RXdir-RD)/WDH) ^2) [kg m^-3 s^-1])
DX = if( x>0, temp, 0 )

[squar_o]

Thank you very much for the input, it works. Unsurprisingly the answer was right in front of me in the docs - I just misinterpreted it