Use of Pdesolve with Time-Varying Boundary Condition

Forum|Forum|2 years ago
April 9, 2024
2 replies
2703 views

Dear PTC Community,

I was recently working with a Mathcad Prime 9.0 worksheet that uses the Pdesolve function, but what I can't seem to do is define a first-derivative boundary condition (Neumann condition) in which temperature at the boundary is one of the arguments. I get the error message "Bad algebraic constrain." I've attached a zip file containing the worksheet. If you can, please help me troubleshoot this issue, or else let me know that what I'm trying to do is not possible.

Thanks for your time!

--Bob

1_Pde-Temperature2.zip

Mathcad Usage

Best answer by LucMeekes

Hi Bob,

This is what I get in (good old) Mathcad 11:

I don't think this does anything different from what you are trying.

Possible pdesolve in Prime is not yet up to standards.

I've attached my sheet. Try to create an html file from it, using the sheet translator.

If it produces a similar result, then Prime should be able to it too. In that case translate my sheet to Prime and run that.

Success!
Luc

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-MFra-

21-Topaz II

It seems to me, observing the figure, that the system under consideration has cylindrical symmetry, so the Fourier equation should be used in this symmetry.

L

LucMeekes

Answer

23-Emerald IV

Hi Bob,

This is what I get in (good old) Mathcad 11:

I don't think this does anything different from what you are trying.

Possible pdesolve in Prime is not yet up to standards.

I've attached my sheet. Try to create an html file from it, using the sheet translator.

If it produces a similar result, then Prime should be able to it too. In that case translate my sheet to Prime and run that.

Success!
Luc

1_LM_20240409_pdesolve.zip

R

rjwolfgang

Author

4-Participant

Yeah, unfortunately it looks like Mathcad 11 is more flexible with the boundary conditions. Mathcad Prime 9.0 throws an error when you have a boundary condition that is the first derivative with respect to the independent variable also dependent on the function itself, i.e., dT(L,t)/dx has T(L,t) as one of its terms. I have a Mathcad 11 license, but I can't install it ever since PTC changed its licensing policy. If I have a Mathcad Prime license, is it possible that PTC would somehow allow me to install an earlier version of Mathcad as well? Maybe I should start a new thread under the 'licensing' topic.

Thanks for your help!

--Bob