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Temperature dependent thermal property in CFX |
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August 21, 2009, 15:14 |
Temperature dependent thermal property in CFX
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#1 |
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Subhadeep
Join Date: Aug 2009
Posts: 14
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Hi
Trying to define a material in CFX pre with temperature dependent expression This is what I entered : 2.9544 + 0.02*T [W m^-1 K^-1] While running gives me error saying : Error processing expression 'Thermal Conductivity'. Error at position 17. Units [W m^-1 K^-1] are associated with an expression that is not dimensionless. What should the correct expression be? Should I take out [W m^-1 K^-1] ? Thanks .... |
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August 21, 2009, 15:56 |
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#2 |
Senior Member
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Location: Technische Universität Chemnitz
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The problem is that T has a units associated with it. What you need to do is make sure the final result ends with a [W m^-1 K^-1]. So we would have to change it to:
2.9544 [W m^-1 K^-1] + 0.02 [W m^-1 K^-2] * T Notice the Kelvin unit on T will cancel the one associated with the 0.02 providing the correct units. Let me know if you need further explaination. |
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August 21, 2009, 16:07 |
Thanks
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#3 |
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Subhadeep
Join Date: Aug 2009
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That helped ...
After reading the messages I thought on similar lines but used it like this and that still gave me an error : 2.9544 [W m^-1 K^-1] + 0.02*T [W m^-1 K^-2] |
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August 21, 2009, 16:29 |
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#4 |
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Needs to be exactly as I have it. Again the units of [W m^-1 K^-2] must be associated with 0.02 and not as you have it where CFX is trying to associate T with [W m^-1 K^-2] when it already has units of [K].
Last edited by NickFL; August 24, 2009 at 09:28. |
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August 22, 2009, 21:21 |
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#5 | |
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Jack
Join Date: Mar 2009
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Hi Sir,
let me explaining ! For example, for the heat flux boundary condition, you have to build a variable called Fluxoa, like this (where t is time in [s], and Fluxoa is a heat flux in [W m^-2]: Fluxoa (B*(19453.29701*(t/A)^3.07678)/(4.73947^3.07678+(t/A)^3.07678)) A 1.0 [s] B 1.0 [W m^-2] So, the Fluxoa variable will have the [W m^-2] final heat flux unit ! with kind regards, Rogerio . Quote:
Last edited by rogbrito; August 28, 2009 at 13:40. |
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March 22, 2012, 02:52 |
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#6 |
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will this be also valid if i were to define a temperature dependent body load please?
__________________
Thank you for your kind attention. Kind regards, mactech001 Currently using: ANSYS v13 |
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