Execution of the program

 

Choice of the shape functions:
The default shape function type is linear functions, but quadratic functions can be chosen using the “Parameters -> Shape-function type” menu.

Loading the necessary data files:
By clicking on the “Browse .net” button (or “Browse .dat”) you will be able to choose among the available .net files (or .dat files) on the disk.
After choosing the wanted files, they can be loaded by clicking on the “Load” button.

Computation of the stiffness matrix and right-hand side without taking the boundary conditions into account:
After the loading process, the “Matrix Assembly” button is enabled, which, when clicked assembled the stiffness matrix and the right-hand side without taking the boundary conditions into account.
During the assembling process, the animation speed can be modifies using the “Speed” scroll bar (if the scroll bar is all the way to the left, the animation is no longer displayed).

Taking the boundary conditions into account:
By clicking on the three next buttons, the boundary conditions are taken into account.
During the different assembling processes, the elements of the mesh and the entries of the matrix with which the program works are colored in red. The non zero entries are colored in blue so the user can see that the matrix is sparse. The green elements correspond to the Dirichlet nodes.
The zoom of the matrix can be changed with a scrollbar. If the zoom is big enough, the rows and column numbers are displayed, and if the zoom is all the way to the left, the values of the elements of the matrix are printed on the panel.

Solution of the FE system of equations:
When all the boundary conditions have been taken into account, the “Solution” button can be used to start the solving process. By selecting the “Parameters -> Display -> Display S’S Decomposition” menu item, the upper triangular matrix S of the STS decomposition is first displayed. Then an animation represents the forward and backward substitution algorithm.
After the solving process, the temperature field is displayed along with a temperature scale.

Mesh refinement:
If the program works with piecewise linear shape-function, the mesh can be refined (“Accessories -> Mesh Refinement”). Before starting such a refinement, the program will ask for the maximum allowed temperature variation between two consecutive nodes, it will then refine the mesh as many times as needed in order for every temperature variation to be under the specified one. Entering a maximum variation of zero will refine the entire mesh once (every triangle will be split in four). It is also possible to save the files corresponding to the refined mesh, to do so tick the corresponding option in the “Parameters -> New files creation ...” menu.

Interpolation of the solution:
The representation of the solution can be enhanced using the “Interpolation” scroll bar: the triangles are cut into four triangles and the solution is computed on each new triangle using a linear interpolation. As the computation of this refinement can be a bit long a progress bar indicates the amount of work done.

Saving the solution:
The solution (the coordinates of the nodes and their temperature) can be saved using the “Accessories -> Save Solution” menu.

Renumbering of the nodes:
The nodes can also be renumbered with the “Accessories -> Renumbering” menu (see Renumbering). The menu item “Auto-renumbering of nodes with quadratic functions” is selected by default. It enables the solving process to run faster. It is also possible to save the files corresponding to the renumbered mesh, to do so tick the corresponding option in the “Parameters -> New files creation ...” menu.

Other possibilities:
The “Language” menu can be used at any time to change the language.
During the assembling or the solving process, it is possible to save Jpeg images of the mesh and the matrix by using the “Accessories -> Create Jpeg” menu.
The “Parameters -> Display” menu has two more options: “Display boundary conditions” and “Display the node numbers”, these options turn on or off the displaying of the Dirichlet nodes (colored in green) and the highlighting of the borders isolating the mesh from the exterior, and also of the numbers of the nodes of the mesh.