# Error in defining expression

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 August 12, 2016, 07:09 Error in defining expression #1 Senior Member   Aja Join Date: Nov 2013 Location: India Posts: 351 Rep Power: 5 Hi, I am defining an expression, but i have a error as follows: Why does this happen? Thanks. Last edited by aja1345; August 16, 2016 at 08:06.

 August 12, 2016, 07:24 #2 Member   urosgrivc Join Date: Dec 2015 Location: Slovenija Posts: 93 Rep Power: 2 What does this mean? )( try )*( multiplication if this is what you want? aja1345 likes this.

August 12, 2016, 07:34
#3
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Aja
Join Date: Nov 2013
Location: India
Posts: 351
Rep Power: 5
Quote:
 Originally Posted by urosgrivc What does this mean? )( try )*( multiplication if this is what you want?
Yes!!! Thanks

 August 12, 2016, 09:10 #4 Senior Member   Aja Join Date: Nov 2013 Location: India Posts: 351 Rep Power: 5 Hi, Why does the following error happen? I want to define gas constant of air. Last edited by aja1345; August 16, 2016 at 08:05.

 August 12, 2016, 10:07 #5 Senior Member   Aja Join Date: Nov 2013 Location: India Posts: 351 Rep Power: 5 Why does unit of the following expression equal to Kg^2 m s^-5 K^-2? volumeInt(((Thermal Conductivity/(Temperature)^2)*((1/(Density*(R/(M air))))*(Pressure.Gradient X)^2+(1/(Density*(R/M air)))*(Pressure.Gradient Y)^2+(1/(Density*(R/M air)))*(Pressure.Gradient Z)^2)))@Rotary R=gas constant According to above, Unit of Volume integral should be equal to W/ K or kg m^2/S^-3 K^-1 . I assumed fluid as ideal gas presently. therefore>>>>> P=Ro*R*T T=P/(RO*T) ......... Thanks. Last edited by aja1345; August 16, 2016 at 08:07.

 August 14, 2016, 14:08 #6 Member   urosgrivc Join Date: Dec 2015 Location: Slovenija Posts: 93 Rep Power: 2 I dont think that [Kj] means enithing. definitly not with smal j I am asking the experts now-> (is kilo(k) , mega(M) and other prefixes suported instead of multipliers) as I havent tried it out myself. Joul=J should work but than, for Kilo you should multiply it by 1000. so you would end up with [J kg^-1 K^-1]*1000 aja1345 likes this.

 August 14, 2016, 19:31 #7 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 12,545 Rep Power: 97 Yes, CFX supports the SI unit system with prefixes. But you have to get it correct, as urosgrivc states. Joule is J and kilo prefix is k, so the unit if kJ. aja1345 likes this.

 August 15, 2016, 07:15 #8 Senior Member   Aja Join Date: Nov 2013 Location: India Posts: 351 Rep Power: 5 Thanks. What is your suggestion about defining expression? I am grateful that guide me about this case. Last edited by aja1345; August 16, 2016 at 08:08.

 August 15, 2016, 07:41 #9 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 12,545 Rep Power: 97 I think the temperature gradient functions work in CFD-Post. Have a look in the CFX reference manual for a description of the available variables and functions you can apply to them. Also the temperature gradient variables will be available under the puzzlingly titled "..." button for plotting on surfaces, vectors etc. aja1345 likes this.

August 15, 2016, 15:28
#10
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Aja
Join Date: Nov 2013
Location: India
Posts: 351
Rep Power: 5
Quote:
 Originally Posted by ghorrocks Also the temperature gradient variables will be available under the puzzlingly titled "..." button for plotting on surfaces, vectors etc.
Thanks.

I don't understand this your statement. Can you explain more?

What is "..." button?

 August 15, 2016, 15:42 #11 Senior Member   Join Date: Jun 2009 Posts: 530 Rep Power: 13 Insert an User Defined Variable, for the method select Gradient, and select Temperature for the variable. CFD-Post will create the Temperature.Gradient variable. You can then use it as needed. aja1345 likes this.

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