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Potential created by a current source in soil
Posted Apr 19, 2017, 10:29 a.m. EDT 1 Reply
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Hello,
I want to model the electric potential distribution in the soil created by a surfacic current density source (disk).
I have created a hemisphere to represent the soil (4km radius) and added a constant resistivity.
I put at the top centre of the hemisphere a current density source with a disk.
Finally for the boundary conditions I put the ground condition on the external face to represent the zero potential at infinity (4km here) and the insulation condition at the air/soil interface.
I tried to compare the results from Comsol with the analytical expression V(r)=(rho*I)/(2*pi*r) where r is the distance from the current source but the error is below 1% only for a distance from 0.06 meters to 20 meters from the source and the rest is not good.
I do not know how to deal with the ground condition at infinity and if the insulation boundary condition is correct (might be dV(x,y,0)/dz=0).
You can find attached a picture of the geometry.
Thank you!
I want to model the electric potential distribution in the soil created by a surfacic current density source (disk).
I have created a hemisphere to represent the soil (4km radius) and added a constant resistivity.
I put at the top centre of the hemisphere a current density source with a disk.
Finally for the boundary conditions I put the ground condition on the external face to represent the zero potential at infinity (4km here) and the insulation condition at the air/soil interface.
I tried to compare the results from Comsol with the analytical expression V(r)=(rho*I)/(2*pi*r) where r is the distance from the current source but the error is below 1% only for a distance from 0.06 meters to 20 meters from the source and the rest is not good.
I do not know how to deal with the ground condition at infinity and if the insulation boundary condition is correct (might be dV(x,y,0)/dz=0).
You can find attached a picture of the geometry.
Thank you!
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1 Reply Last Post Apr 19, 2017, 10:56 a.m. EDT
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Posted:
8 years ago
Antonin,
you should compare your model result with a sperical capacitor with a finite outer radius. If you need to go to infinity you may try to add an infinite element layer to the model.
The insulation BC at the cross section should be fine.
Cheer
Edgar
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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com