I have another question: in Which way does the torque calculation work? I had some problems with my model (squared core with an airgap, within the airgap a single wire):

I've got the problem that the magnetic torque isn't zero when the axis is through the middle of the wire:

4: component 1: res: magnetic force 1= 3.734628378772E+000

5: component 1: res: magnetic force 2 = -1.101039591209E-003

6: component 1: res: magnetic force 3 = 6.378247999766E-004

7: component 1: res: magnetic torque = -3.516128841510E+003

When I use an axis parallel to the wire in an distance of 10mm i get the following result:

4: component 1: res: magnetic force 1= 3.734628378772E+000

5: component 1: res: magnetic force 2 = -1.101039591209E-003

6: component 1: res: magnetic force 3 = 6.378247999766E-004

7: component 1: res: magnetic torque = -1.197103472730E+006

Another unexpected effect is that the length of the axis influences the magnitude of the torque. For example when the axis is the length of the wire ( Torque Origin(3) = Real 100 0 -10; Torque Axis(3) = Real 0 0 20) the torque is -4.379584261120E+002.

What I'm doing wrong? The force seems to be ok (direction and magnitude). Is there some problem with the coordinates?

The SIF:

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 = sw.sif
Post File = sw.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 2"
Equation = 2
Material = 2
End
Body 3
Target Bodies(1) = 3
Name = "Body Property 3"
Equation = 2
Material = 3
End
Body 4
Target Bodies(1) = 4
Name = "Body 4"
Equation = 1
Material = 1
Body Force = 2
! Torque Groups(1) = integer 1
End
Body 5
Target Bodies(1) = 5
Name = "Body 5"
Equation = 2
Material = 3
End
Solver 3
Equation = MgDynPost
Potential Variable = AV
Calculate Current Density = True
Procedure = "MagnetoDynamics" "MagnetoDynamicsCalcFields"
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 = 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
!Torque Group Origins(1,3) = Real 100 0 -10
!Torque Group Axes(1, 3) = Real 0 0 20
Calculate Electric Field = True
Calculate Magnetic Field Strength = True
Calculate Nodal Forces = Logical True
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 = 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 = loop
Exec Solver = After Timestep
End
Solver 2
Equation = MgDyn
Fix Input Current Density = True
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 = 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 5
Equation = "Savedata"
Procedure = "SaveData" "SaveScalars"
filename = "withouttorque.dat"
save component results = logical true
End
Equation 1
Name = "Wire+SW"
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
End
Material 2
Name = "Steel"
Electric Conductivity = 1.449e6
Relative Permeability = 1000
Density = 7850
End
Material 3
Name = "Air"
Electric Conductivity = 0
Relative Permeability = 1
Density = 1.205
End
Body Force 1
Name = "Volume Current"
Current Density 1 = Equals Volume Current 1
Current Density 3 = Equals Volume Current 3
Current Density 2 = Equals Volume Current 2
End
Body Force 2
Name = "SW"
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(2) = 4 26
Name = "Ground"
Potential = 0
End
Boundary Condition 2
Target Boundaries(2) = 13 27
Name = "Current Density"
Current Density = 141471061
End
Boundary Condition 3
Target Boundaries(1) = 20
Name = "Border"
AV {e} = Real 0
End
Component 1
Name = string "metal"
Master Bodies(1) = integer 4
Torque Origin(3) = Real 100 0 -20 ! Real 100 10 -20 with torque
Torque Axis(3) = Real 0 0 40
Calculate Magnetic Force = Logical True
Calculate Magnetic Torque = Logical True
End
```