May 26, 2026 · Planck Labs · 1 min read
The absorbing boundary condition that makes finite-domain wave simulation possible: how it works, when it fails, and why integral equation methods do not need one.
Draft — coming soon.
This note will introduce the perfectly matched layer (PML), the absorbing boundary technique that allows time-domain and frequency-domain volume solvers to truncate an unbounded radiation domain to a finite computational box. We will cover the original Bérenger formulation, the stretched-coordinate interpretation, common failure modes (low-frequency breakdown, glancing incidence), and why integral equation methods avoid the issue entirely.
Related
May 19, 2026 · 1 min
FDTD vs FEM vs MoM: a plain-English comparison
The three dominant families of numerical methods for electromagnetic simulation, what each is good at, and where each one breaks down.
May 12, 2026 · 1 min
What is electromagnetic simulation?
An introduction to numerical solution of Maxwell's equations: what these solvers compute, where they are used, and the families of methods that dominate the field.