Electromagnetic Plane Wave (emPlaneWaveT.pre)

Keywords:

electromagnetics, plane wave, periodic boundary conditions, wave launcher

Problem Description

A linearly-polarized (with electric field in the y-direction) electromagnetic pulse with a sinusoidal amplitude on a plane wave is launched from the left side (x=0) to propagate in the x-direction. The transverse (y,z) boundary conditions are periodic.

This simulation can be performed with a VSimBase license.

Opening the Simulation

The Electromagnetic Plane Wave example is accessed from within VSimComposer by the following actions:

  • Select the NewFrom Example… menu item in the File menu.
  • In the resulting Examples window expand the VSim for Basic Physics option.
  • Expand the Basic Examples (text-based setup) option.
  • Select Electromagnetic Plane Wave (text-based setup) and press the Choose button.
  • In the resulting dialog, create a New Folder if desired, and press the Save button to create a copy of this example.

The basic variables of this problem should now be alterable via the text boxes in the left pane of the Setup Window, as shown in Fig. 148.

image 1

Fig. 148 Setup Window for the Electromagnetic Plane Wave example.

Input File Features

The input file sets the wavelength to be one-third of the box length. It computes the TIMESTEP stability limit for the time step and sets the actual time step to TIMESTEP_FACTOR times the stability limit for the time step.

Running the Simulation

After performing the above actions, continue as follows:

  • Proceed to the Run Window by pressing the Run button in the left column of buttons.
  • To run the file, click on the Run button in the upper right corner. of the window. You will see the output of the run in the right pane. The run has completed when you see the output, “Engine completed successfully.” This is shown in Fig. 149.
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Fig. 149 The Run Window at the end of execution.

Visualizing the Results

After performing the above actions, continue as follows:

  • Proceed to the Visualize Window by pressing the Visualize button in the left column of buttons.

The electric and magnetic field components can be found in the scalar data variables of the data overview tab.

  • Make sure the Data View drop down is set to Data Overview.
  • Here you can see Variables. Expand the Scalar Data.
  • Expand E
  • Select E_y

Initially, no field will be seen, as one is looking at Dump 0, the initial dump, when no fields are yet in the simulation. Move the slider at the bottom of the right pane to see the electric field at different times. The final time is shown in Fig. 150.

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Fig. 150 Visualization of plane wave as a color contour plot.

Further Experiments

To see more wavelengths, change the value of the WAVELENGTHS variable. What happens to the waves when there are very few cells in a wavelength?

See the wave reflect off the right boundary by running for more time steps.

To see a numerical instability, increase TIMESTEP_FACTOR to greater than one.

To see controlled dispersion, change to a 1D simulation and set TIMESTEP_FACTOR to unity.

Try changing NDIM to 3 to see the how the simulation is uniform across the z- dimension.