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[SCIRUN-USERS] Regarding applyFEM current source

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  • From: Vikas R bhat <>
  • To: Jess Tate <>,
  • Subject: [SCIRUN-USERS] Regarding applyFEM current source
  • Date: Mon, 18 Sep 2017 17:28:06 +0530

​​Thank you so much,

Pls clear my simple doubt in applyfem.

From the chapter 5 tutorial and applyfemcurrent source description in scirun users, it is  clear that the Neumann bc are applied to the nodes of tetmesh domain containing a dipole source at 'p'. We have simulated a dipole source inside tetmesh and trying to calculate numerically the corresponding nodes covering the mesh that are initialised using Neumann bc (from the output of applyfemcurrent module). So in  view scene, we setfield the output of applyfemcurrent module with the mesh to get the initial potentials at nodes (in ch 5, it is mentioned that "b is a source vector which indicates the flux through the nodes and all other nodes are zero").  

Could you pls tell me how to calculate the relationship between dipole at 'p' and the node values that got assigned to tetmesh nodes. I am not using matrix to the build fem matrix module for conductivities. In A𝜙=b, how b is calculated.

Dipole placed at p(198,17,414) -------> strength (0,0,12)

The values assigned to the nodes of mesh from output of applyfem that has to be used with stiffness matrix:

Node a (159, 16, 436) ---------> value= 0.0605
Node b (211, 37.8, 454.8) ---------> value= 0.0882
Node c (245, -8, 435) ---------> value= -0.0214
Node d (180, 36, 355) ---------> value= -0.127

Is it possible to calculate numerically the initial  del phi (spatial derivative of phi) assigned to nodes (using Neuman bc)?. 

⃗   =  -σ_i.  n ̂  . ∇𝜙_𝑖

𝑛 ̂. ∇𝜙_𝑖=  𝐽 /𝜎_𝑖

𝑛 ̂ = normal comp., σ_i = conductivity , ∇𝜙_𝑖 = initial pot.,  ⃗  =current vector.

Do I have to just divide the current vector by the conductivity of the tetmesh element?   
Do the conductivity values vary inside elements. When I add these node element data, I am getting zero . Does this mean, it is satisfying laplace eq.
Pls help me out. (pls find the attached image).

Inline image 2


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  • [SCIRUN-USERS] Regarding applyFEM current source, Vikas R bhat, 09/18/2017

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