# Perfectly matched layer

### From AbInitio

Revision as of 18:40, 7 November 2005 (edit)Mihai (Talk | contribs) ← Previous diff |
Revision as of 18:48, 7 November 2005 (edit)Mihai (Talk | contribs) (numerical reflections) Next diff → |
||

Line 1: |
Line 1: | ||

The '''perfectly matched layer''' ('''PML''') approach to implementing absorbing boundary conditions in FDTD codes was proposed by Berenger in 1994 (see [http://dx.doi.org/10.1006/jcph.1994.1159]). | The '''perfectly matched layer''' ('''PML''') approach to implementing absorbing boundary conditions in FDTD codes was proposed by Berenger in 1994 (see [http://dx.doi.org/10.1006/jcph.1994.1159]). | ||

The approach involves surrounding the computational cell with a medium that in theory absorbs without any reflection electromagnetic waves at all frequencies and angles of incidence. Berenger showed that such a medium can be constructed as a lossy anisotropic dielectric with electric and magnetic conductivities of equal magnitude. (Of course, the magnetic conductivity requirement makes this an unphysical medium.) | The approach involves surrounding the computational cell with a medium that in theory absorbs without any reflection electromagnetic waves at all frequencies and angles of incidence. Berenger showed that such a medium can be constructed as a lossy anisotropic dielectric with electric and magnetic conductivities of equal magnitude. (Of course, the magnetic conductivity requirement makes this an unphysical medium.) | ||

+ | |||

+ | The finite-difference implementation of PML requires the conductivities to be turned on gradually over a distance of a few grid points to avoid numerical reflections from the discontinuity. |

## Revision as of 18:48, 7 November 2005

The **perfectly matched layer** (**PML**) approach to implementing absorbing boundary conditions in FDTD codes was proposed by Berenger in 1994 (see [1]).
The approach involves surrounding the computational cell with a medium that in theory absorbs without any reflection electromagnetic waves at all frequencies and angles of incidence. Berenger showed that such a medium can be constructed as a lossy anisotropic dielectric with electric and magnetic conductivities of equal magnitude. (Of course, the magnetic conductivity requirement makes this an unphysical medium.)

The finite-difference implementation of PML requires the conductivities to be turned on gradually over a distance of a few grid points to avoid numerical reflections from the discontinuity.