Help Needed with gprMax Simulation Results for Different Buried Objects
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Ankur Jyoti Kalita
Sep 11, 2023, 3:20:02 AM9/11/23
to gprMax-users
Hello everyone,
I'm seeking assistance with a gprMax simulation issue I encountered while working on two cases.
In one case, I buried an aluminium object, and in the other, an iron object, both within a sandy medium. The issue is that despite the differences in the materials' properties (like conductivity and relative permittivity), I got the same reflected signals for both objects.
Simulation parameters for both cases are identical, including object depth, radius, antenna position, etc.
Domain Size:
Length (x): 1350 mm
Width (y): 750 mm
Height (z): 600 mm
Soil Configuration:
Soil Relative Permittivity- 10.0, Conductivity- 0.002 S/m
Both objects are cylindrical and are buried in the soil.
Soil is filled up to a depth of 400 mm within the domain.
Object properties:
Aluminium: Relative Permittivity- 10.8, Conductivity- 3.5e7 S/m
Iron: Relative Permittivity- 14.2, Conductivity- 1e7 S/m
Depth of the object: 60 mm
Diameter of the object: 50 mm
I've attached the simulation configuration files (IN files) and the GPR signal responses for both cases. I'm puzzled by the similarity in the results and would greatly appreciate any guidance on whether I've made errors in setting up the simulations or if there are other factors at play.
Thank You.
I'm seeking assistance with a gprMax simulation issue I encountered while working on two cases.
In one case, I buried an aluminium object, and in the other, an iron object, both within a sandy medium. The issue is that despite the differences in the materials' properties (like conductivity and relative permittivity), I got the same reflected signals for both objects.
Simulation parameters for both cases are identical, including object depth, radius, antenna position, etc.
Domain Size:
Length (x): 1350 mm
Width (y): 750 mm
Height (z): 600 mm
Soil Configuration:
Soil Relative Permittivity- 10.0, Conductivity- 0.002 S/m
Both objects are cylindrical and are buried in the soil.
Soil is filled up to a depth of 400 mm within the domain.
Object properties:
Aluminium: Relative Permittivity- 10.8, Conductivity- 3.5e7 S/m
Iron: Relative Permittivity- 14.2, Conductivity- 1e7 S/m
Depth of the object: 60 mm
Diameter of the object: 50 mm
I've attached the simulation configuration files (IN files) and the GPR signal responses for both cases. I'm puzzled by the similarity in the results and would greatly appreciate any guidance on whether I've made errors in setting up the simulations or if there are other factors at play.
Thank You.
Ankur Jyoti Kalita
Sep 11, 2023, 3:25:38 AM9/11/23
to gprMax-users
Sorry,
There was a slight mistake, depth of the object is 200 mm from the soil surface. However, in my simulation, no matter what depth both objects were placed (same for both cases), it produced similar results.
There was a slight mistake, depth of the object is 200 mm from the soil surface. However, in my simulation, no matter what depth both objects were placed (same for both cases), it produced similar results.
Michael Fehér
Sep 13, 2023, 3:49:37 AM9/13/23
to gprMax-users
Hey,
what the FD-algorithm does, it simulates the electromagnetic waves in your model.
And just as it is in reality, you'll get a nearly total reflection of your pulse an surfaces of metal.
In your case, the significance of conductivity is very high! the ratios aren't as different as it seams 1,75*10^9 for Aluminium versus 0.5*10^9 for iron. both of them are far above every ratio FD can discriminate.
Metal (no matter if copper, iron, steel, aluminuim or whatever) burried in a moderate or low conductive medium will reflect 100% of the energy of your GPR signal.
so you won't see any difference.
Sure thera are differences, but these are way too small to see, maybe too small to be handled by float.
Cheers, Micha
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