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evaluation of Heat Equation on a plane with a Heat source and convective b.c.

Posted: 04 May 2021, 15:56
by Lorenzop99
Hello everidbody

i want to say that i'm new about Elmer and i need some help.

i've started to study a Inconel Plane with dimension of 2mmx6mmx340mm with a heat source of 0.78 MW/m^2.

You can see the b.c. at the image at this link:
https://ibb.co/3MLZKVv

i have three doubt:

in particular i'll want to set this boundary condition:

1)the top, left, right, forward and behind surface: Adiabatic boundary condition, is it correct asses this condition adding an heat flux=0?
2)below surface: convection b.c., is it correc set this condition adding the value of heat transfer coefficient in W/m^2 K and temperute?

3)About the body force i'll want to add the Heat source of 0.78 MW/m^2, how can i set?

thanks to those who answer me!

Re: evaluation of Heat Equation on a plane with a Heat source and convective b.c.

Posted: 04 May 2021, 16:01
by kevinarden
Have you reviewed the Elmer's Model Manual Heat Equation and then worked through
the first two tutorials in the tutorial manual
https://www.nic.funet.fi/pub/sci/physics/elmer/doc/

Re: evaluation of Heat Equation on a plane with a Heat source and convective b.c.

Posted: 04 May 2021, 16:08
by Lorenzop99
Thank you for the answer; i've already make the two tutorial, unfortunately I couldn’t solve the problem

Re: evaluation of Heat Equation on a plane with a Heat source and convective b.c.

Posted: 04 May 2021, 19:01
by kevinarden
1) I believe the default "do nothing" boundary condition is Adiabatic, so if you assign nothing the heat flux will be zero. You can also assign heat flux = 0.
2) You can make the bottom surface radiate heat using idealized radiation, external temperature, and an emmisivity factor
3) Body force is assigned using the body force option

You should specify an initial condition temperature, or it will assumed to be zero.
You should do everything in SI units.
case.sif
(2.13 KiB) Downloaded 29 times
result.png
(38.42 KiB) Not downloaded yet

Re: evaluation of Heat Equation on a plane with a Heat source and convective b.c.

Posted: 04 May 2021, 19:20
by Lorenzop99
Thank you for all!

The last doubt is about the second point:

2) i don't have radiation boundary condition but a convection Boundary condition, how can i set this kind of b.c.?

about the measure conversione for to pass to W/m^2 to W/kg you is correct divide for the density and for the thickness?


you can find my sif case is attachment
case.sif
(2.31 KiB) Downloaded 35 times
Thank you!

Re: evaluation of Heat Equation on a plane with a Heat source and convective b.c.

Posted: 04 May 2021, 23:56
by kevinarden
I believe that can be done as a heat flux BC

[attachment=0]case.sif[/attachment

If you just want it to convect by the coefficient then you don't need to enforce a flux

Boundary Condition 1
Target Boundaries(1) = 5
Name = "heatflux"
Heat Flux BC = True
Heat Transfer Coefficient = 1
End

Re: evaluation of Heat Equation on a plane with a Heat source and convective b.c.

Posted: 05 May 2021, 20:47
by Lorenzop99
thank you!