The software was built around the physics coupling approach, making the modeling of lightning strikes on an airplane easy and affordable. In particular, modeling this effect with COMSOL Multiphysics is possible because of the software's ability to solve virtually any set of coupled differential equations. In addition, other physical effects can be added, such as wind cooling and black-body radiation heating that arises from the hot lightning channel, which is the 1-cm thick channel of ionized hot air (10,000-20,000°C) where the lightning discharge flows onto an airplane wing.
Figure 1 shows the results of one such simulation of the heating caused by a current pulse from lightning injected into the leading edge of a wing that consists of two layers of different anisotropic and homogeneous composite materials. The current is injected across a small circular area in the front. The figure shows the distribution of current density on a number of vertical and horizontal slices through the structure at an instant in time just after the lightning has struck. In the left image, the slice plot shows current density, while streamlines indicate the current's path. In the figure on the right, the slice plot describes the temperature, and the boundary plot in the middle of the geometry shows the electric potential.
The figure on the right shows where the temperature distribution reaches the material's melting temperature of 300°C. It is evident that the outer material layer, which has the lowest electrical conductivity, is severely damaged by the temperature rise while the inner layer is not. Furthermore, it is easy to study how the extent of the damage is influenced by the degree of material anisotropies.
This methodology was validated for simulating lightning strikes against actual test results. Radiative heating from the lightning channel also plays an important role. The findings from these simulations had a major impact on construction techniques and provided useful design rules for the next generation of advanced materials for aircraft structures.
Electromagnetic simulations have been used to analyze a variety of other aircraft-related applications such as antenna diagrams, antenna-to-antenna couplings, radar cross-sections, interference propagation, printed circuit board designs, and test setup optimization.
Saab Group also used the software for an external customer, ABB, in which case they modeled the electromagnetic effects on the casing (the electromagnetic shielding) surrounding a voltage substation. These electricity distribution systems are used to transform voltages between different forms and levels and thus provide the link between high-voltage transmission lines and the domestic electricity supply.