magpar software requirements

The procedure for hybrid finite element/boundary element problems is more complicated. The magpar software (Scholz et al., 2003a) requires that the geometry of the problem be defined with a finite element mesh. For this, any finite element modelling software can be used, provided that its output is converted to the AVS unstructured cell data (UCD) format. We used the finite element mesh generator NETGEN (Schöberl, 2003). Natively, this software does not create AVS/UCD format files, however it does have a fairly flexible approach to constructive solid geometry (CSG) allowing for the creation of complex geometries.

Figure 2.17 shows how the memory requirements of magpar scale as a function of both the number of surface elements and the volume elements, while figure 2.18 demonstrates magpar and OOMMF memory scaling.

Figure 2.17: Memory usage scaling with magpar derived from runtime measurements

Figure 2.18: Memory usage of OOMMF and magpar. The dotted lines for magpar represent a high volume element to surface element ratio (i.e. a sphere) and the solid line represents a low volume element to surface element ratio (as in a thin film). Curve fits are shown for magpar; in all cases the circles represent measured results.

In order to prepare the neutral file format created by NETGEN for magpar we created a custom Python script to convert this file to an AVS/UCD-compliant mesh.

The simulation problem and material parameters are generated with another bespoke Python script to create the complex input files required for simulation with magpar. At this point the problem can now be solved using either a standalone uniprocessor or symmetric multi-processing workstation, or a clustered supercomputer.

Further details can be found in appendix E.