2D Maxwell complex coordinate stretching PML

In summary, the conversation discusses the derivation of the perfectly matched layer for the TM mode Maxwell's equations using complex coordinate stretching. The transformed equations include additional terms due to integration, but there is a discrepancy in the number of auxiliary differential equations present. The suggestion is to look into 2D absorbing boundary conditions, specifically for Z-polarized E and XY-polarized H fields traveling in the XY plane. The implementation has been done in 1D, but further research is needed for 2D cases.
  • #1
Knaapje
8
0
Hello, I'm trying to derive the perfectly matched layer for the TM mode Maxwell's equations using a complex coordinate stretching. As seen in http://math.mit.edu/~stevenj/18.369/pml.pdf . But I'm running in a bit of trouble somehow.
[itex]\partial_t H_x =-\mu^{-1} \partial_y E_z\\
\partial_t H_y =\mu^{-1} \partial_x E_z\\
\partial_t E_z =\epsilon^{-1} \left(-\partial_y H_x + \partial_x H_y \right)[/itex]​

After applying the transformations in the x- and y-direction, the equations look like this:
[itex]i\omega H_x = -\mu^{-1} \partial_y E_z + \sigma_y(y) H_x\\
i\omega H_y = \mu^{-1} \partial_x E_z + \sigma_x(x) H_y\\
i\omega E_z = \epsilon^{-1} \left(-\partial_y H_x + \partial_x H_y\right) +\left(\sigma_x(x) + \sigma_y(y)\right) E_z + \psi + \phi + \frac{i\sigma_x(x) \sigma_y(y) E_z}{\omega}\\
i\omega\psi = \epsilon^{-1}\sigma_x(x)\partial_y H_x\\
i\omega\phi =-\epsilon^{-1}\sigma_y(y)\partial_x H_y[/itex]​

Where two auxiliary differential equations have appeared due to integration terms in the Ez differential equation. However, it appears as though I should have another one, as there is still an integration term left in the Ez differential equation. This is contrary to what I've heard/read should happen. Is there any reason why this term should be absent (or why it does not contribute a lot to the solution in the physical domain)?

Any help would be greatly appreciated, as I've been trying to figure this out for some time.

EDIT: fixed the blank space between the equations
 
Last edited:
  • #3
I am no expert but you can look into "2D absorbing boundary conditions."
I got that part correct, right? You have a Z polarized E field, xy polarized H field traveling in xy plane?
http://www.engr.uky.edu/~gedney/courses/ee624/notes/EE624_Notes6.pdf


I have implemented this in 1D, you need to search for 2D cases.
 
Last edited by a moderator:

1. What is a 2D Maxwell complex coordinate stretching PML?

A 2D Maxwell complex coordinate stretching PML (perfectly matched layer) is a numerical technique used in computational electromagnetics to simulate electromagnetic wave propagation in 2-dimensional structures. It is commonly used in finite-difference time-domain (FDTD) simulations to absorb outgoing waves and reduce reflections from the edges of the computational domain.

2. How does a 2D Maxwell complex coordinate stretching PML work?

The PML works by stretching the computational domain in the complex coordinate plane. This stretching allows for the absorption of outgoing waves and reduces reflections at the boundaries, making the simulation more accurate. The PML is also designed to have a gradually increasing absorption coefficient, so that the absorption is strongest at the edges of the domain and decreases towards the interior.

3. Why is a PML necessary in 2D Maxwell simulations?

In 2D Maxwell simulations, reflections from the edges of the computational domain can cause inaccuracies in the results. The PML helps to reduce these reflections and improve the accuracy of the simulation. It also allows for a larger computational domain without introducing artificial boundaries, which can also affect the accuracy of the results.

4. Are there any limitations to using a 2D Maxwell complex coordinate stretching PML?

While the PML is an effective technique for reducing reflections in 2D Maxwell simulations, it does have some limitations. The PML is most effective for simulations with a constant permittivity and permeability, and may not perform well in highly dispersive or anisotropic materials. Additionally, the implementation of the PML can be computationally expensive and may increase the simulation time.

5. How is the performance of a 2D Maxwell complex coordinate stretching PML evaluated?

The performance of a PML is typically evaluated by examining the reflection coefficient at the edges of the computational domain. A lower reflection coefficient indicates better absorption of outgoing waves and therefore a more accurate simulation. Other factors that can be evaluated include the computational cost and the effect on the accuracy of the results.

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