Using Built-in pec in #material

[Del Buan]

Dear gprMax team,

I'm currently creating a model in gprMax. I'm looking into how to use the built-in PEC (Perfect Electrical Conductor) in gprMax as one of my materials in the #material section.

I came across the documentation and it stated that in order to call a material, it needs to be in this format: #material: f1 f2 f3 f4 str1.

 For PEC, the parameters are:

eps_r = 1

Sigma [S/m] = inf (infinite)

mu_r = 1

Sigma* [Ohm/m] = 0

And translates to the format according to the documentation: #material: 1 inf 1 0 pec.

Therefore, to use the built-in PEC in gprMax as one of my materials according to the format above, do I replace f2 to "inf" or is there other methods for this?

Thank you in advance!

[Antonis Giannopoulos]

To use the building PEC material you hast specify it in any of the object building commends without the need to define it with a material command. PEC is applied as a boundary condition where the electric field is zero. The electrical parameters do not really matter. On PEC materials the electric field is zero. It is simple. Equally you can use free_space to get the properties of empty space (vacuum) as default. 

Hope this helps

Antonis

[Del Buan]

Hi Prof. Antonis,

My scenario would be importing a geometry "geometry_1.h5" and I would like to define the PEC material in the material.txt file to set some metallic bars. How can I do that? 

Thank you!

[Craig Warren]

If you are importing your own geometry and materials then it is probably best to define your own PEC, e.g. #material: 1 inf 1 0 mypec, in your materials file.

Craig

[Del Buan]

Hi Craig,

I have defined the method you have suggested: #material: 1 inf 1 0 in my materials file for the PEC material. But when I see my B-Scan, the part that I have defined the PEC supposed to have a stronger reflection, but it has a weaker reflection instead. These are the parameters for my input file: 

#domain: 1.80 1.30 0.20
#dx_dy_dz: 0.002 0.002 0.002
#time_window: 10e-09

#waveform: ricker 10 1.3e9 my_ricker
#hertzian_dipole: x 0.4 0.20 0.10 my_ricker
#rx: 0.5 0.20 0.10

#src_steps: 0.02 0 0
#rx_steps: 0.02 0 0

#pml_cells: 20 20 20 20 20 20

#geometry_objects_read: 0 0 0 C:\Users\dev\OneDrive\Desktop\gprMax_Simulations\Simulations\geometry_1.h5 C:\Users\dev\OneDrive\Desktop\gprMax_Simulations\Simulations\materials.txt 

After checking the input file, I can't seem to find the issue as to why there is a weaker reflection for the PEC part where it supposed to have a stronger reflection. Need help on this, thank you!

[Craig Warren]

Can you post a screenshort or export of the model geometry from Paraview please.

Craig

[Del Buan]

Hi Craig,

The below screenshot is the model geometry from ParaView. From the geometry in the screenshot, the part that I wanted to put my PEC is annotated in red.

[Craig Warren]

So when you select your mypec material in Paraview does it show the correct volume?

Craig