Help with finite element program I developed for Diff Eqns

AI Thread Summary
A finite element program (MFEM) developed in Java for solving boundary value problems (BVP) and initial value problems (IVP) is encountering issues with a generalized eigenvalue problem related to wave propagation in a rectangular waveguide in TE mode. The program computes the scalar Helmholtz equation correctly without applying Dirichlet boundary conditions, but the results differ when these conditions are applied, affecting the field plots. The user has utilized nodal-based rectangular elements and generated the mesh using a custom program called Mmesh. Additional information, including output plots, has been provided to assist with troubleshooting. The discussion seeks guidance on resolving the discrepancies in results when boundary conditions are enforced.
mdn
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I developed finite element program (MFEM) in java for BVP &IVP to compute partial differential equation.
I am facing one problem and description is as follows
my problem is on generalized eigenvalue problem generated in wave propagation through rectangular wave guide in TE mode. (Differential equation is scalar Helmholtz equation).

I am getting correct answer but without specifying Dirichlet boundary condition! (Tangential component of electric field should be zero on boundary element).
and if i applied boundary condition, getting same answer but field plot is different .
one thing i used nodal based rectangular element and mesh generated in my own flash program Mmesh.

please help me to solve above problem.
 
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mdn said:
I developed finite element program (MFEM) in java for BVP &IVP to compute partial differential equation.
I am facing one problem and description is as follows
my problem is on generalized eigenvalue problem generated in wave propagation through rectangular wave guide in TE mode. (Differential equation is scalar Helmholtz equation).

I am getting correct answer but without specifying Dirichlet boundary condition! (Tangential component of electric field should be zero on boundary element).
and if i applied boundary condition, getting same answer but field plot is different .
one thing i used nodal based rectangular element and mesh generated in my own flash program Mmesh.

please help me to solve above problem.

Welcome to the PF.

We probably will need a lot more information to be of help on this question. Can you post some plots that show the output from your program?
 
Dear Berkeman,
I have attached field plots from my program for TE10(without bc),TE20 (without bc),TE11(without bc) and TM11 (with bc).
Thanks in advance.
 

Attachments

  • te10wbc.jpg
    te10wbc.jpg
    25.5 KB · Views: 457
  • te20wbc.jpg
    te20wbc.jpg
    25.9 KB · Views: 436
  • te11wbc.jpg
    te11wbc.jpg
    26.9 KB · Views: 458
  • tm11bc.jpg
    tm11bc.jpg
    27.5 KB · Views: 445

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