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06-19-2020
11:16 AM

06-19-2020
11:16 AM

Thermal transfert diffusion and convection

Hello,

I have a problem : I want to analyse the thermal heat evolution of a wall with fluid heat variation. Can you help me ?

Thank you.

Michel

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6 REPLIES 6

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06-19-2020
01:51 PM

06-19-2020
01:51 PM

Re: Thermal transfert diffusion and convection

You have two constraints for Phi_d(x,t):

With 'Flux' it is equal to: -a * Temp.x(x,t) which may be a function of t AND x

With 'Cond. aux limites': Phi_h_S(t)-Phi_h_P(t), which is a function of t, not of x.

If I define:

I can:

Then the solve block becomes:

So you have two different constraints for Phi_d(x,t), but you could also state:

Which leaves Phi_d.x(x,t) undefined, and that might explain why I get an 'undefined variable or function' error message.

If you could set initial conditions for Phi_d(x,t), you might be able to solve for Temp and Phi_d simultaneously.

Success!

Luc

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06-20-2020
09:57 AM

06-20-2020
09:57 AM

Re: Thermal transfert diffusion and convection

Hi,

In order not to confuse and not to waste time in the interpretation of your file, you should provide us with the text and the equations to be used in Mathcad, including the initial and boundary conditions.

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06-21-2020
04:00 AM

06-21-2020
04:00 AM

Re: Thermal transfert diffusion and convection

The topic interests me, however thanks anyway.

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06-21-2020
08:36 AM

06-21-2020
08:36 AM

Re: Thermal transfert diffusion and convection

I publish something about the cooling. I don't know if you are interested:

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06-21-2020
09:04 AM

06-21-2020
09:04 AM

Re: Thermal transfert diffusion and convection

How about the attached?

You have weird boundary conditions though: one end varies from -10 to +10, the other from -300 to + 300.

Alan

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06-22-2020
09:39 AM

06-22-2020
09:39 AM

Re: Thermal transfert diffusion and convection

I am very interested in all yours responses. Thank you very much for spending time helping me for this problem. The data being confidential, I had simplified the functions, which could have made the subject less comprehensible to you. The thermal exchange and boundary condition functions are described with very severe transients. now I will put in practice your precious advice.

Thank you all.

Michel