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November 6, 2013, 19:31 
Finding my current.

#1 
New Member
Terry
Join Date: May 2013
Posts: 9
Rep Power: 4 
My problem is that I know what I need to do, I'm just no sure how to code it.
Here's the integral I'm working with: I=ρ b∫ ∂V/∂n dl rho and b are known constants. ∂V/∂n is the partial of Voltage normal to the plane and dl is obviously my differential length. With this integral I'm finding the corona current around a wire with fairly high current. I'm basically having issues with two parts. The first is figuring out how to find the partial of voltage normal to my plane (wire). I have solved for the voltage field throughout my mesh but don't know how to single out the values around the wire. I know that the values at the wire itself all are normal to the plane so all I need to find are the magnitudes of each mesh cells voltage at the wire. Any help is much appreciated!! 

November 7, 2013, 04:44 

#2 
Senior Member
Bernhard
Join Date: Sep 2009
Location: Delft
Posts: 790
Rep Power: 12 
The integral that you wrote here, is this a line integral?
For the surface normal gradient, you have to snGrad() functions available. 

November 7, 2013, 18:01 

#3 
New Member
Terry
Join Date: May 2013
Posts: 9
Rep Power: 4 
Since I'm only analyzing a 2D surface, it is essentially a line integral. I'm just integrating around the circumference of a circle (the wire).
And thanks for the snGrad() tip, I'm looking at that function now. 

November 8, 2013, 15:21 

#4 
New Member
Terry
Join Date: May 2013
Posts: 9
Rep Power: 4 
Basically all I've done so far is modify the electrostatic solver to solve for the Efield throughout the duct.
Code:
while (runTime.loop()) { Info<< "Iteration = " << runTime.timeName() << nl << endl; solve(fvm::laplacian(phi) + rho/epsilon0); rhoFlux = k*mesh.magSf()*fvc::snGrad(phi); solve(fvm::ddt(rho) + fvm::div(rhoFlux, rho)); volVectorField E("E",fvc::grad(phi)); //Solve For EField a) how to find the magnitude of my efield normal to the wire. As stated above I just need the values of the efield at the wire since all Evectors at the wire are normal. b) how to find the length of each mesh cell at the wire. I could always hard wire a value in for this, but that's not exactly what I would like to do. Any help that anyone could provide would be GREATLY appreciated. I've been stuck at this point for a month now, and don't know where else to turn. 

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