A Perfectly Matched Layer node () applies a complex coordinate scaling to a layer of virtual domains surrounding the physical region of interest. When appropriately tuned, this layer absorbs all outgoing wave energy in frequency-domain problems, without any impedance mismatch — causing spurious reflections — at the boundary.

To add a Perfectly Matched Layer to any Component, on the Definitions toolbar click Perfectly Matched Layer.

The Label is the default perfectly matched layer name.

The default Name (for the first perfectly matched layer in the model) is pml. The Name provides a namespace for variables created by the Perfectly Matched Layer node. For example, the scaled x coordinate can typically be accessed in equations and postprocessing as pml1.x. See the Equation View subnode for a complete list of available variables.

Select a set of domains conforming to the selected geometry type. See Standard Geometry Configurations.

Select a Type: Cartesian (the default), Spherical, Cylindrical, or User defined.

Select a Coordinate stretching type: Polynomial (the default), Rational, or User defined. See PML Implementation for help on making a decision.

Select an option from the Typical wavelength from list: Physics interface (the default) or User defined. If Physics interface is selected, select one of the interfaces supporting PMLs from the Physics list. If User defined is selected, enter a value or expression for the Typical wavelength. The default is 1.

For the predefined Polynomial and Rational stretching types, enter a value or expression for the PML scaling factor and the PML scaling curvature parameter which can be used to tune the PMLs for wave fields with evanescent components or wavelengths deviating from the free-space wavelength of plane waves. See further PML Implementation. The defaults are 1 for both.

For the User defined stretching type, select Real part of stretching function and Imaginary part of stretching function from functions defined under Global>Definitions or under Definitions in a component, or leave the default value None, which for the real part is interpreted as f(ξ) = ξ and for the imaginary part as f(ξ) = 0. Any function node defining a single function of one or two arguments is eligible for use as a stretching function. The first argument is interpreted as a dimensionless distance, ξ, in the range 0 to 1, and the second argument — if present — as the typical wavelength.