CEL problem
Hi,
I need some help to define a moving function by the expression, the following is the function I created: (((0.8[cm])^2(z5[cm])^2)^0.5((1.0(z5[cm])^2/(0.75[cm])^2)*(0.1[cm])^2)^0.5)*(t/tt)/0.4 When z=5.8[cm], which is supposed to be zero, while when I evaluate or run my simulation, an error shows up, as the following: The problem was: INVALIDEXPONENTIATION FURTHER INFORMATION The problem was encountered in executing the expression for: value The complete expression is: (((0.8[cm])^2(z5[cm])^2)^0.5((1.0(z5[cm])^2/(0. The error occurs on subexpression: ((0.8[cm])^2(z5[cm])^2)^0.5 BACKGROUND INFORMATION These values were set before reaching the current expression: Name = Expression = Value tt = 1 [s] = 1.00000 END OF DIAGNOSTIC OUTPUT FOR CFX EXPRESSION LANGUAGE Can Anyone point out how to solve it? I really appreciate! Thanks, 
use /1[cm] to cancellate the unit

Quote:

I suspect you will need to put more brackets in it to ensure the order of operations is correct. I suspect it is evaluating something like 1.0(z5[cm])^{2/(0.75[cm])^2} (the curly brackets are my addition) and that is an invalid operation due to the units of the exponential operation.

((1.0(z5[cm])^2/(0.75[cm])^2)*(0.1[cm])^2)^0.5 appears to be invalid, it is a (negative vlaue)^0.5 at higher Z value.

yes, thanks John, it seems there is one point in the plane I want to use the function exceed 5.8 for just a little, but it does influence, I just made some modification, it works now.
thanks again for all. 
Ha!
I've got one for ya. Input from CFX5 The problem was: INVALIDEXPONENTIATION FURTHER INFORMATION This is from the static enthalpy at outlet, I haven't changed any pre set equations. It happens when I try to run the gas compressor performance macro. 
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