PdnMesh Graphical User Interface

When you run the program, you will see the main window as in Figure 1.1, “The contour plot”. The menubar has 3 menus.

File Menu

File->Open opens a new coordinate file.

File->Import DXF imports a CAD DXF file. For more information on this, please refer to Chapter 3, Converting DXF Files.

File->Save saves contour plot, mesh, gradient, potentials etc.

File->Quit exits the program.

View Menu

View->Mesh draws the mesh.

View->Contours draws the contours.

View->ColourFill fills colours according to the contours.

View->Grad draws the gradient.

View->Legend draws the legend.

View->Draw Output draws the output i.e. contours, gradient. In this mode you can modify triangle properties ( boundary ) and divide triangles into more triangles.

View->Draw Input draws the input i.e. different materials will have different colours. In this mode, you can modify material properties using the popup menu.

View->Preferences...You can change drawing preferences such as background colour by selecting this menuitem.

Solve Menu

Solve->Mesh+Solve Once regenerates the mesh and solves the problem, using only one iteration.

Solve->Solve Once solves the problem without generating the mesh again.

Solve->Mesh+Solve Iteratively generates the mesh, and solves the problem iteratively, until iteration limit has reached. In each iteration, the mesh is refined.

Solve->Integrate... integrates the potential to find the charge (in an electrostatic problem) on Dirichlet boundaries.

Solve->Edit Material...If you enable this mode, you can edit material properties just by clicking on a material. You need to select this menuitem again to disable this mode.

Solve->Change Options... dialog window for changing solution options. See Figure 1.6, “Solve Options Dialog” for more detail.

Figure 1.6. Solve Options Dialog

Solve Options Dialog

The options that can be changed using the above dialog are as follows:

  • Min. Area: Minimum area of a triangle of the mesh.

  • Max. Area: Maximum area of a triangle of the mesh.

  • Tri. Badness: Maximum badness of a triangle in the mesh. Badness is the ratio of the longest edge to the shortest edge of a triangle.

  • Equation Type:

    • Poisson for Poisson and Laplace equations.

    • Poisson (Sparse) for Poisson and Laplace equations using sparse matrices and Conjugate Gradient solver.

    • Homogeneous Helmholtz for homogeneous waveguide (eigenvalue problems).

    • Inhomogeneous Helmholtz for inhomogeneous waveguide problems.

    • Helmholtz find beta for finding the propagation constant when the frequency or k is given.

    • Helmholtz find k0 for finding the frequency when the propagation constant is given.

  • Use Full Matrix Solver: Most eigenvalue problems have symmetric positive definite matrices. So, we only need half of the matrix for solution. However, the problems where we have to find beta and k0 will not always give us positive definite matrices. So in this case, enable this option to use full matrices.

  • Use ARPACK Eigensolver: If you have a very large problem to solve (several thousand unknowns), select this option. It will use very little memory but takes longer time.

  • No. of Eigenmodes: Only for equation other than Poisson, the number of eigenmodes to find, starting from the dominant mode.

  • Contour Levels: No. of contour levels to plot

  • Iteration Limit: Maximum no of iterations in the iterative form of solution.

  • Wave frequency beta: used when solving Helmholtz find k0 problems.

  • Wave frequency k0: used when solving Helmholtz find beta problems.

Note that the units used in all of the above parameters are normalised. In other words, you do not have to worry about units or absolute values.

Popup Menu

This is the menu you get from right clicking the mouse. It has following items.

Popup->0_Mode switch to default mode. Basically does nothing. Useful if you want to stop zooming etc.

Popup->Triangle Info Mode Switch to retrieving and changing properties of triangles. In this mode, If you are in View->Draw Output mode, once you left-click on a triangle, you get a dialog like Figure 1.7, “Triangle Info Dialog” and you can change the boundary of the triangle.

Figure 1.7. Triangle Info Dialog

Triangle Info Dialog

If you are in View->Draw Input mode, once you left-click on any area, you get a dialog like Figure 1.8, “Material Info Dialog” and you can change the boundary properties like permittivity and permeability. This is useful especially if you need to solve inhomogeneous waveguide problems where you need to specify both the permittivity and permeability.

Figure 1.8. Material Info Dialog

Material Info Dialog

Popup->Triangle Split Mode In this mode, once you left-click on a triangle, it will be split. This is useful if you need to manually refine the generated mesh.

Popup->Zoom Window In this mode, you can select a rectangular area using the mouse left button and zoom in.

Popup->Zoom Back Once you select this option, the display will zoom back to previous view.

Popup->Zoom All Once you select this option, the display will zoom to global view.

Popup->3D Window Once you select this option, a new window will be created to display the contour plot in 3D like Figure 1.3, “3D contour plot”. In the 3D window, you can zoom and rotate using mouse buttons. Move the mouse with left pressed for rotation. Move the mouse with middle pressed for zooming.

Popup->Next Eigenmode This option is useful if you solve the Helmholtz equation for more than one eigenmode. By selecting this option, you can switch between each eigenmode.

Popup->Quit Exits the program.