## BC for infinite longe wire

Numerical methods and mathematical models of Elmer
Bavragor
Posts: 32
Joined: 07 Nov 2013, 14:10
Antispam: Yes

### BC for infinite longe wire

Hi,

At the moment I try to create some simple cases for myself to get into Elmer electromagnetic simulation. At the moment I have a problem with the boundary condition for an infinite long wire. My model consists of 4 cylinders/hollow cylinders. In the middle the wire, than air, electrical steel (at the moment with const. rel. permeability) and again air as last material (picture). hidden surfaces (air) for better overview
model.png (151.23 KiB) Viewed 1188 times
In my understanding the bc in z-driection have to be Magnetic Flux Density 3 = Real 0.
The results with different bc:

1. Magnetic Flux Density 3 = Real 0 at every face in z-direction (also at the two ends of the wire)
-->WhitneyAVSolver ends with:
Program received signal SIGSEGV: Segmentation fault - invalid memory reference.

Backtrace for this error:
#0 ffffffffffffffff
2. Same error for other bc like Magnetic Flux Density 3 = Real 0 at every face in z-direction instead of the faces for the wire. But at first there wasn't this error but the solution of statcurrent or whitneyav doesn't converge. Yet I can't rebiuld this error. Anyone an idea what this error means or how to avoid it? What bc should be set for an infinite long wire?

I usw Elmer under Windows 10 and 7 (Elmer 8.0) with a model created in Salome.

The SIF-file:

Code: Select all

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

Simulation
Max Output Level = 10
Coordinate System = Cartesian
Coordinate Mapping(3) = 1 2 3
Steady State Max Iterations = 1
Output Intervals = 1
Timestepping Method = BDF
BDF Order = 1
Solver Input File = inf.sif
Post File = inf.ep
Coordinate Scaling = 1e-3
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) = 10
Name = "Body 1"
Equation = 1
Material = 1
Body Force = 1
End

Body 2
Target Bodies(1) = 11
Name = "Body 2"
Equation = 2
Material = 2
End

Body 3
Target Bodies(1) = 12
Name = "Body 3"
Equation = 2
Material = 3
End

Body 4
Target Bodies(1) = 13
Name = "Body 4"
Equation = 2
Material = 2
End

Solver 2
Equation = MgDyn
Variable = AV
Fix Input Current Density = True
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 = CG
Linear System Max Iterations = 5000
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 3
Equation = MgDynPost
Calculate Magnetic Field Strength = True
Potential Variable = AV
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 = CG
Linear System Max Iterations = 5000
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 1
Equation = Static Current Conduction
Calculate Volume Current = True
Variable = Potential
Procedure = "StatCurrentSolve" "StatCurrentSolver"
Exec Solver = Before Simulation
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 = CG
Linear System Max Iterations = 5000
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 4
Equation = Result Output
Procedure = "ResultOutputSolve" "ResultOutputSolver"
Output Format = Vtu
Output File Name = inf
Exec Solver = After Timestep
End

Equation 1
Name = "Wire"
Active Solvers(4) = 2 3 1 4
End

Equation 2
Name = "Air+Core"
Active Solvers(3) = 2 3 4
End

Material 1
Name = "Copper"
Electric Conductivity = 59.59e6
Porosity Model = Always saturated
Density = 8960.0
Relative Permeability = 1
End

Material 2
Name = "Air"
Electric Conductivity = 0
Porosity Model = Always saturated
Density = 1.205
Relative Permeability = 1
End

Material 3
Name = "Steel"
Electric Conductivity = 1.449e6
Porosity Model = Always saturated
Density = 8960.0
Relative Permeability = 1000
End

Body Force 1
Name = "BodyForce 1"
Current Density 1 = Equals Volume Current 1
Current Density 3 = Equals Volume Current 3
Current Density 2 = Equals Volume Current 2
End

Boundary Condition 1
Target Boundaries(1) = 5
Name = "Ground"
Potential = 0
Magnetic Flux Density 3 = Real 0
End

Boundary Condition 2
Target Boundaries(1) = 6
Name = "Potential"
Current Density = 1e7
Magnetic Flux Density 3 = Real 0
End

Boundary Condition 3
Target Boundaries(1) = 4
Name = "Border"
AV {e} = 0
End

Boundary Condition 4
Target Boundaries(6) = 1 2 3 7 8 9
Name = "inf"
Magnetic Flux Density 3 = Real 0
End
``````
Bavragor
Posts: 32
Joined: 07 Nov 2013, 14:10
Antispam: Yes

### Re: BC for infinite longe wire

I got it on my own. In fact pretty easy. Only have to set AV {e} 2 = 0 and AV {e} 1 = 0 for all BCs in z-direction