Error in PDEsolve function with system of PDE's

[ptc-5208368]

Hello Mathcad community,

I'm a student trying to get a Mathcad sheet to work. I want to solve a system of 2 partial differential equations (PDE) with the Pdesolve function. I got several different sheets working with just 1 PDE, but now I have a system of 2 PDE's I can't get it working.

My calculation is a transient cooldown of a 2 layer composite ''plate'' with a steady state temperature distribution to begin with. I got 2 PDE's to discribe the transient cooldown of the 2 different layers and 4 boundary conditions (2 on the ends of the ''plate'' and 2 in the middle at the contact point of both layers). I'm stuck at the error: "The boundary conditions are not consistent with the endpoints specified for the spatial range". Which is strange because 2 PDE's need 4 boundary conditions. I attached a MC11 and a MC15 sheet. I hope someone can help me to solve this.

Regards,

Jaap

[AndyWesterman]

Hello Jaap,

I don't think that MathCad can understand if you define a condition in the middle of the variable range.

Boundary conditions need to be set at maximum or minimum values.

If you need to define the boundary condtion as your sheet then it might be necessary to split the PDE into 2 parts to meet the needs of the software.

Attached file, I've ghanged the boundary condition & added an array for the 2 functions that the PDE solver will return.

Regards

Andy

[ptc-5208368]

Hi Andy,

Thanks for your answer. I was thinking about it again and I indeed might only need 2 boundary conditions, because the problem is still 1 dimensional. Unfortunately your adjustment didn't give the desired result, but I appreciate your input. Maybe you have any other idea of how to fix this?

[Werner_E]

Did you try to split the task into two parts, as Andy suggested?

Think he was somly demonstrating that the solve block works if the boundary conditions really reflect the boundaries and not the middle.

[AlanStevens · Accepted solution]

Don't know if the attached helps. It's an old file that I've modified to incorporate some of your data.

Alan

[ptc-5208368]

Thank you so much Alan! Your sheet solved my problem!

Jaap