2 First 2D electrostatic solution In preparation, install either the professional or basic version of the Electrostatics Toolkit . In this chapter, we’ll run through the steps of the solution and analysis of a 2D electrostatic problem without going into detail. The goal is a quick demo of the capabilities of EStat . Subsequent articles will cover details of program techniques. A notable feature of our programs is dual input there are two options for supplying geometric and material data for solutions: Interactive : the standard method for modern finite-element programs where you fill in items in dialogs. This option is useful for new users and for a quick setup of a new system. Text :
the classic method using input scripts. This option allows experienced users to make changes to setups easily and allows automatic program operation under the control of external programs or batch files. Scripts also provide a permanent archive of setups. In this demo calculation, we will check out prepared input scripts before running them using the built-in text editors of Mesh and EStat . For more detailed work, it’s useful to have a good text editor like ConText. Before starting, we’ll need to make some provisions for data organization. A little effort in the beginning circumvents headaches later.
Using a file manager (like FreeCommander), navigate to a location where you would like to create a general directory for your finite-element calculations and create the directory Simulations Create the sub-directories Electrostatics and Electrostatics \ Practice . In the right-hand window, navigate to C: \ fieldp basic \ tricomp \ Examples \ EStatExamples . We will copy a prepared example for our work. Highlight the files with prefix ElectronDiode and copy them to the Practice directory. Figure 2 shows the resulting setup. Click the desktop shortcut to run FPController ( fpcontroller.exe , Fig. 3 ). The Mesh and EStat buttons should be active as shown.
If not, click the Program folder button and navi- gate to C: \ fieldp basic \ tricomp . Click the Data folder button and navigate to c: \ Simulations \ Electros Subsequently, all input/output operations will target this folder. There are three steps in a finite-element solution: Define the geometry of the solution space and divide objects into small volumes ( ele- ments ). The process is called mesh generation . Create and solve a large set of linear equations to approximate the governing partial differential equation (such as the Poisson equation for electrostatics). The goal is to determine the electrostatic potential on points of the mesh ( nodes ).
Analyze the results use the potential values to find physical quantities of interest ( e.g. , electric field, field energy, capacitance,....). The first function is performed by the Mesh program ( mesh.exe ) and the second and third functions by the EStat program ( estat.exe ). Meshing is performed by a separate program because the same mesh may be used for different types of solutions. Output from Mesh is compatible with PerMag (magnetic fields), TDiff (thermal transport) and other solution 6