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Interpolation function in variable

Posted 26 oct. 2011, 11:12 UTC−4 Heat Transfer & Phase Change, Materials Version 4.2a 3 Replies

Hans Parmentier
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I want to use a temperature depending interpolation function for the thermal conductivity (Cp)

I made an interpolation graph in the global definitions. (named int1)

There in X-axis it is temperature in degC
and in Y axis it is Cp (J/Kg K)

now I want to use this graph in my heat transfer mode

I think I need to make a variable called Cptemp with a link to int1

but there I get always the following
unknown variable int1

in the heat transfer mode I would change then Cp from material to user defined.

How can this basic problem be solved?
3 Replies Last Post 27 oct. 2011, 02:32 UTC−4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 26 oct. 2011, 11:27 UTC−4
Hi

if you define a function/operator and you want to call it you mustadd the variable such as int1(T[1/degC]). Now as T is a field depending on x,y,z you need to define this for a formula having a domain or a boundary or an edge or a point as selected items.

Note use rather T in [K], the default, or take at least care with the units, ther are new functionalities for unit definitions in the function in v4.2a

--
Good luck
Ivar
Hi if you define a function/operator and you want to call it you mustadd the variable such as int1(T[1/degC]). Now as T is a field depending on x,y,z you need to define this for a formula having a domain or a boundary or an edge or a point as selected items. Note use rather T in [K], the default, or take at least care with the units, ther are new functionalities for unit definitions in the function in v4.2a -- Good luck Ivar
Hans Parmentier
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Posted: 1 decade ago 27 oct. 2011, 01:59 UTC−4
Ivar,

thanks a lot for solving this basic problem which is occuring often because we have lot of data in function of temperature.
Ivar, thanks a lot for solving this basic problem which is occuring often because we have lot of data in function of temperature.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 27 oct. 2011, 02:32 UTC−4
Hi

there are several essential and basic issues I had, when beginning with comsol, particularly how to understand variables, and really to catch that everything (most "variables" ) are in fact depending on x,y,z. and that most GUI fields apply to element volums of size *dx*dy*dz therefore the "density dimensions on most default field units

--
Good luck
Ivar
Hi there are several essential and basic issues I had, when beginning with comsol, particularly how to understand variables, and really to catch that everything (most "variables" ) are in fact depending on x,y,z. and that most GUI fields apply to element volums of size *dx*dy*dz therefore the "density dimensions on most default field units -- Good luck Ivar

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