Question about expression in CFXpost(need help!)
2 Attachment(s)
Hi,
I defined some expressions in CFXpre. After running the simulation, I open the result file(.res file) in CFX post, then press the button 'Apply'(like 'figure1' in the attachment) , an error message window jumps out.('figure2' in the attachment). I look for the solution of this error in the tutorial, but do not find any helpful answer. I try to define some new expressions , but always have this error message no matter how do I change the unit. May I ask how to solve this problem? How to write correct expression in CFXpost? Is the CFXPost expression language different from CfXPre? Thank you very much! 
What is the expression giving the error? It seems pretty clear there is a problem with units. It's saying you are trying to subtract a dimensionless quantity from a quantity with units of metres. It can't be the expression posted in your first image that is giving the error.

Quote:
Another question why 'if( 10 [m]< z && z <10 [m], Pressure, 0 [pa] )' gives error message 'ERROR: Error in 'if' statement at position 1. The 'true' and 'false' expressions have inconsistent dimensions.'? Their units are [pa]. 
The correct syntax for CEL if statements is:
if( cond_expr, true_expr, false_expr ) where: cond_expr: is the logical expression used as the conditional test true_expr: is the mathematical expression used to determine the result if the conditional test is true. false_expr : is the mathematical expression used to determine the result if the conditional test is false. I think the problem is that Pressure is a variable so it probably doesn't know where to evaluate it at. Just saying Pressure probably returns multiple values whereas 0 [Pa] is just one value. 
Actually the inconsistent dimensions may be referring to units. It could be confused if you put [pa] instead of [Pa].

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