Numeerisen analyysin ja laskennallisen
tieteen seminaari
13.3.2006 klo
14.15
U356
Matti Lassas, TKK, Matematiikan laitos
Absorbing boundary
conditions in electromagnetism
We review absorbing boundary conditions, particularly so-called
Perfectly Matched Layer (PML). Absorbing boundary conditions are used
in computer simulations for scattering problems, for simulating radar
or cellular phones etc. When simulating the waves in infinite space one
faces the problem that any computer has only finite memory. Thus the
domain of simulation has to be cut finite. The boundary of this new
domain should cause as little echo as possible. The echo-less boundary
structures implemented at the boundary are called absorbing boundary
conditions. Mathematically, the PML-structure is equivalent for
interpreting the real space as a submanifold of the complex space and
stretching the real space into the complex direction. In the talk we
give introduction to the PML method, show numerical results and explain
the connection of PML to quantum mechanical resonances. Presented
results are done in collaboration with Erkki Somersalo, Jukka Liukkonen
and Seppo Järvenpää.