boundaries on the bottom and left sides. A useful feature of finite-element solutions is that unspecified boundaries automatically assume the Neumann condition, exactly what we what. We’ll simply leave the boundaries alone. Click the Export MIN tool to save a copy of the work and then exit the drawing editor. To see the result of the work, choose File/Edit file and pick CoaxialCylinders.MIN . Here is the content: * File:
CoaxialCylinders.MIN * ------------------------------------------------------- GLOBAL XMESH 0.00000 15.00000 0.20000 END YMESH 0.00000 15.00000 0.20000 END END * ------------------------------------------------------- REGION FILL DIELECTRIC L 15.00000 0.00000 0.00000 0.00000 L 0.00000 0.00000 0.00000 15.00000 A 0.00000 15.00000 15.00000 0.00000 0.00000 0.00000 END * ------------------------------------------------------- REGION FILL INNERELECTRODE L 5.00000 0.00000 0.00000 0.00000 L 0.00000 0.00000 0.00000 5.00000 A 0.00000 5.00000 5.00000 0.00000 0.00000 0.00000 END * ------------------------------------------------------- REGION OUTERBOUNDARY A 15.00000 0.00000 0.00000 15.00000 0.00000 0.00000 END * ------------------------------------------------------- ENDFILE The region vectors and coordinates should look familiar.
The commands at the top set the target element sizes. For now, we’ll accept the defaults. The final step is generate a mesh file ( CoaxialCylinders.MOU ) from the region bound- ary specifications ( CoaxialCylinders.MIN ). In the main Mesh menu, choose File/Load/Load script (MIN) and pick the file you just created. Choose Process and then Plot-repair to view the result (Fig. 14 ). Is it a good mesh? Qualitatively, the answer is yes because the boundaries are relatively smooth and all features are well resolved ( i.e. , spatial variations of potential will be spread over many elements). We shall make this conclusion more quantitative in future chapters.
In the next chapter, we will use the mesh for field calculations and comparisons. 19