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Importing real data heat flux boundary condition to COMSOL

Posted Feb 20, 2013, 11:28 p.m. EST Heat Transfer & Phase Change Version 4.3a 6 Replies

Vinh Nguyen
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Hello all,
I'm working on a 2D transient heat transfer project and I can't figure out how to import real data for heat flux vs.time in COMSOL. It only allow me to input a fix value or function, not discrete data points.
Any idea?
Thank you very much,

Vinh
6 Replies Last Post May 19, 2013, 10:04 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 21, 2013, 1:54 a.m. EST
Hi

check the help/doc on the Definition Function Interpolation (+read from File)

--
Good luck
Ivar
Hi check the help/doc on the Definition Function Interpolation (+read from File) -- Good luck Ivar
Vinh Nguyen
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Posted: 1 decade ago Feb 21, 2013, 10:07 p.m. EST
Hi Ivar,
I was able to create a function with "interpolation function". Now do you know how could I use that function as my inward heat flux in my model?
Thank you very much,

Vinh
Hi Ivar, I was able to create a function with "interpolation function". Now do you know how could I use that function as my inward heat flux in my model? Thank you very much, Vinh
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 22, 2013, 1:43 a.m. EST
Hi

if you have an interpolation function of the type int1(arg1,arg2), you simply use it in the place for your results calling it as int1(T,H). Now in COMSOL convention, T is a field (T,x,y,z,t) and H too, hence the use of this function implies that you have selected a domain, or boundary where x,y,z are defined (and t by the solver or t=0 the default for non time domain).

Again if you are in 2D COMSOL defaults set z=0, just as in 1D y=z=0 by default, but they are still there ;)

--
Good luck
Ivar
Hi if you have an interpolation function of the type int1(arg1,arg2), you simply use it in the place for your results calling it as int1(T,H). Now in COMSOL convention, T is a field (T,x,y,z,t) and H too, hence the use of this function implies that you have selected a domain, or boundary where x,y,z are defined (and t by the solver or t=0 the default for non time domain). Again if you are in 2D COMSOL defaults set z=0, just as in 1D y=z=0 by default, but they are still there ;) -- Good luck Ivar
Vinh Nguyen
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Posted: 1 decade ago Feb 22, 2013, 3:16 p.m. EST
Hi Ivar,
My interpolation function is as following:
name: int1
t f(t)

0 0.613
60 0.613
120 0.637
180 0.651
240 0.613
300 0.508
360 0.208
420 0.089
480 0.201
540 0.508
600 0.681
"Units"
Arguments: s
functions: W/m^2

Now in my heat flux boundary condition: q0 = int1(t) W/m^2
Is it the right way to call out interpolation for boundary condition? my boundary condition is heat flux vs. time
Thank you,

Vinh
Hi Ivar, My interpolation function is as following: name: int1 t f(t) 0 0.613 60 0.613 120 0.637 180 0.651 240 0.613 300 0.508 360 0.208 420 0.089 480 0.201 540 0.508 600 0.681 "Units" Arguments: s functions: W/m^2 Now in my heat flux boundary condition: q0 = int1(t) W/m^2 Is it the right way to call out interpolation for boundary condition? my boundary condition is heat flux vs. time Thank you, Vinh
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 23, 2013, 8:49 a.m. EST
Hi

that look correct for me, but you should always recheck your results ;)

note that:
1) in the function definition "t" is a dummy variable, you can call a function with any expression or variable name
2) if you define the units in the function definition then you do not need (and should not double up) units in the expression


--
Good luck
Ivar
Hi that look correct for me, but you should always recheck your results ;) note that: 1) in the function definition "t" is a dummy variable, you can call a function with any expression or variable name 2) if you define the units in the function definition then you do not need (and should not double up) units in the expression -- Good luck Ivar
Syazwan Rashidi
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Posted: 1 decade ago May 19, 2013, 10:04 a.m. EDT
Hi Ivar,

i've managed to import experimental datas on interpolation function. However, when i want to call this function in boundary condition, it says "unknown variable"..i was looking to apply force in function of time..can you help me?

Best,
Wan
Hi Ivar, i've managed to import experimental datas on interpolation function. However, when i want to call this function in boundary condition, it says "unknown variable"..i was looking to apply force in function of time..can you help me? Best, Wan

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