Electric Potential in MgDyn

Numerical methods and mathematical models of Elmer
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Josh
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Joined: 18 Jan 2018, 16:13
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Electric Potential in MgDyn

Post by Josh »

Hey,

I am new to Elmer and have some question regarding the MgDyn Solver.
I allready did some examples out of the GUI Tutorial and even got some small minimal working examples working with the electrostatic solver.
In the future I would like to simulate the electric field of wires which are excited by AC,DC or rectangular pulsed voltage.
As there are several transient effects occuring(electric fields, magnetic fields, losses in dielectric material -> joule heating), am I right that I have to use the MgDyn solver to get a good coupling of all these effects?

As before I tried to do a minimal working example to start off with MgDyn and then after understanding everything further improve my studies. But I am a little bit lost with the MgDyn Solver.
For the start I just would like to simulate a plate capacitor in the DC-case(which of course is solvable with the electrostatic solver). I meshed a simple cube of 10mm*10mm*10mm and tried to apply a electric Potential of 1V to one side and 0V to the opposite to get a homogeneous electric field, the dielectric is air.
But I cant figure out how to apply the voltage as a boundary condition.


I allready did some digging and in one thread Peter mentioned that it should be possible to directly apply the electric potential( viewtopic.php?f=3&t=4142&start=0 ) . I also tried to take a look at the .xml and the Models Manual. But I cant figure it out.

Below is my .sif file im working with ElmerGUI.

Code: Select all

Header
  CHECK KEYWORDS Warn
  Mesh DB "." "."
  Include Path ""
  Results Directory ""
End

Simulation
  Max Output Level = 5
  Coordinate System = Cartesian
  Coordinate Mapping(3) = 1 2 3
  Simulation Type = Steady state
  Steady State Max Iterations = 1
  Output Intervals = 1
  Timestepping Method = BDF
  BDF Order = 4
  Solver Input File = case.sif
  Post File = case.vtu
Coordinate Scaling = 0.001
End

Constants
  Gravity(4) = 0 -1 0 9.82
  Stefan Boltzmann = 5.67e-08
  Permittivity of Vacuum = 8.8542e-12
  Boltzmann Constant = 1.3807e-23
  Unit Charge = 1.602e-19
End

Body 1
  Target Bodies(1) = 1
  Name = "Body 1"
  Equation = 1
  Material = 1
End

Solver 1
  Equation = MgDyn
  Variable = AV
  Procedure = "MagnetoDynamics" "WhitneyAVSolver"
  Exec Solver = Always
  Stabilize = True
  Bubbles = False
  Lumped Mass Matrix = False
  Optimize Bandwidth = True
  Steady State Convergence Tolerance = 1.0e-5
  Nonlinear System Convergence Tolerance = 1.0e-7
  Nonlinear System Max Iterations = 20
  Nonlinear System Newton After Iterations = 3
  Nonlinear System Newton After Tolerance = 1.0e-3
  Nonlinear System Relaxation Factor = 1
  Linear System Solver = Iterative
  Linear System Iterative Method = BiCGStab
  Linear System Max Iterations = 500
  Linear System Convergence Tolerance = 1.0e-10
  BiCGstabl polynomial degree = 2
  Linear System Preconditioning = Diagonal
  Linear System ILUT Tolerance = 1.0e-3
  Linear System Abort Not Converged = False
  Linear System Residual Output = 1
  Linear System Precondition Recompute = 1
End

Solver 2
  Equation = MgDynPost
  Calculate Magnetic Field Strength = True
  Calculate Joule Heating = True
  Calculate Nodal Forces = True
  Calculate Current Density = True
  Potential Variable = AV
  Calculate Maxwell Stress = True
  Procedure = "MagnetoDynamics" "MagnetoDynamicsCalcFields"
  Calculate Electric Field = True
  Exec Solver = Always
  Stabilize = True
  Bubbles = False
  Lumped Mass Matrix = False
  Optimize Bandwidth = True
  Steady State Convergence Tolerance = 1.0e-5
  Nonlinear System Convergence Tolerance = 1.0e-7
  Nonlinear System Max Iterations = 20
  Nonlinear System Newton After Iterations = 3
  Nonlinear System Newton After Tolerance = 1.0e-3
  Nonlinear System Relaxation Factor = 1
  Linear System Solver = Iterative
  Linear System Iterative Method = BiCGStab
  Linear System Max Iterations = 500
  Linear System Convergence Tolerance = 1.0e-10
  BiCGstabl polynomial degree = 2
  Linear System Preconditioning = Diagonal
  Linear System ILUT Tolerance = 1.0e-3
  Linear System Abort Not Converged = False
  Linear System Residual Output = 1
  Linear System Precondition Recompute = 1
End

Equation 1
  Name = "mgdyn"
  Active Solvers(2) = 1 2
End

Material 1
  Name = "Air"
  Electric Conductivity = 0
  Porosity Model = Always saturated
  Relative Permittivity = 1
  Relative Permeability = 1
End

Boundary Condition 1
  Target Boundaries(2) = 1 4 
  Name = "high"
  AV = 1
End

Boundary Condition 2
  Target Boundaries(2) = 2 3 
  Name = "gnd"
  AV = Real 0
End

Thanks for the help.

-Josh
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Re: Electric Potential in MgDyn

Post by raback »

Hi

There are plenty of test cases that often serve as suitable starting points for simulation. Have you had a look at the mgdyn examples? There are plenty of them.

-Peter
Josh
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Joined: 18 Jan 2018, 16:13
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Re: Electric Potential in MgDyn

Post by Josh »

Hey Peter,

Thank you for your Suggestion.
Seems like I messed something up in my own example or some settings in the GUI.
The mgdyn_transient testcase fortunately is like my minimal working example and works flawlessly. I am going to take small steps from here.
I am gonna report back when I run into other errors.

Thanks for the hint and for making Elmer possible.

-Josh
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