No Convergence with H-B Curve

Numerical methods and mathematical models of Elmer
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Bavragor
Posts: 32
Joined: 07 Nov 2013, 14:10
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No Convergence with H-B Curve

Post by Bavragor »

Hi Elmer-Users,

I have a simple model of a single wire surrounded by a hollow cylinder out of steel. The cylinder is surrounded by air.
model_sw.png
model_sw.png (62.68 KiB) Viewed 2404 times
The boundary conditions in z-direction is chosen like the model is infinitely long. When I apply a linear permeability to the model everything works as aspected. But when I try to add a nonlinear H-B Curve the model doesn't converge. Have anyone an idea what the problem is? (i tried already: another mesh and other dimesnions of the geometry, another H-B Curve, different solver and preconditioner, another H-B Curve).

Thank you in advance!

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
  Simulation Type = Steady state
  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) = 1
  Name = "Body Property 1"
  Equation = 1
  Material = 1
  Body Force = 1
End

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

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

Body 4
  Target Bodies(1) = 4
  Name = "Body Property 4"
  Equation = 2
  Material = 3
End

Solver 3
  Equation = MgDynPost
  Procedure = "MagnetoDynamics" "MagnetoDynamicsCalcFields"
  Potential Variable = AV
  Calculate Electric Field = True
  Calculate Magnetic Field Strength = 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 = 10000
  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
  Procedure = "StatCurrentSolve" "StatCurrentSolver"
  Variable = Potential
  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 = 10000
  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

Solver 2
  Equation = MgDyn
  Procedure = "MagnetoDynamics" "WhitneyAVSolver"
  Variable = AV
  Fix Input Current Density = 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 = 200
  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 = 10000
  Linear System Convergence Tolerance = 1.0e-8
  BiCGstabl polynomial degree = 2
  Linear System Preconditioning = None
  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 = "Wire"
  Active Solvers(4) = 3 1 4 2
End

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

Material 1
  Name = "Copper"
  Electric Conductivity = 59.59e6
  Relative Permeability = 1
  Density = 8960.0
End

Material 2
  Name = "Steel"
  Electric Conductivity = 1.449e6
  H-B Curve = Variable "nonlin"
    Real Cubic Monotone
     include HB_M330
     End
  Density = 7850.0
End

Material 3
  Name = "Air"
  Electric Conductivity = 0
  Relative Permeability = 1
  Density = 1.205
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) = 2 
  Name = "Ground"
  Potential = 0
  AV {e} 2 = 0
  AV {e} 1 = 0
End

Boundary Condition 2
  Target Boundaries(1) = 10 
  Name = "Potential"
  AV {e} 2 = 0
  AV {e} 1 = 0
  Current Density = 7.96e7
End

Boundary Condition 3
  Target Boundaries(1) = 8 
  Name = "Border"
  AV {e} = 0
End

Boundary Condition 4
  Target Boundaries(6) = 1 3 4 9 11 12 
  Name = "inf"
  AV {e} 2 = 0
  AV {e} 1 = 0
End
the H-B Curve:

Code: Select all

0 0
0.100 30
0.150 35 
0.200 39
0.250 43 
0.300 48
0.350 52 
0.400 56
0.450 60 
0.500 64 
0.550 68 
0.600 72 
0.650 76
0.700 81 
0.750 85 
0.800 90 
0.850 96 
0.900 103 
1.000 120 
1.050 131 
1.100 145
1.150 162 
1.200 185 
1.250 218 
1.300 262 
1.350 331 
1.400 477
1.450 770
1.500 1300
1.550 2142
1.600 3294
1.650 4721
1.700 6338
1.75 8000
1.8 11000
1.85 15000
1.9 22000
1.95 35000
2 50000
2.05 80000
2.1 150000
2.15 500000
2.2 1000000
Last edited by Bavragor on 01 Dec 2016, 12:58, edited 1 time in total.
raback
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Re: No Convergence with H-B Curve

Post by raback »

Hi

There seems to be some discrepancy between the Newton iteration control that the solver uses vs. what ElmerGUI assumes. I just changed the code to also consider the legacy control of Newton linearization as in FlowSolver and HeatSolver etc. As for now you should use in the Solver section

Code: Select all

Newton-Rhapson iteration = Logical True
-Peter
Bavragor
Posts: 32
Joined: 07 Nov 2013, 14:10
Antispam: Yes

Re: No Convergence with H-B Curve

Post by Bavragor »

Thank you!
Bavragor
Posts: 32
Joined: 07 Nov 2013, 14:10
Antispam: Yes

Re: No Convergence with H-B Curve

Post by Bavragor »

Some question to understand that keyword: How is the Newton Raphson iteration used? I think the system is still solved via CG?
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