Hi,
I want to simulate the "Hartmann Problem." I have an electrically conducting, viscous, incompressible fluid between two parallel plates with an applied transverse magnetic field. The pressure varies only in the x-direction. The channel extent in the z-direction is much greater than that in the y-direction so that no variations occur whit z. The electrodes are assumed to be perfect conductors. I have attached the case.sif, themes, and a figure to explain the problem. I have tried to simulate this problem but without convergence. I thank you for any suggestions.
Regards,
Andrea
HARTMANN PROBLEM
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HARTMANN PROBLEM
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- Immagine 2021-05-09 201236.jpg (20.5 KiB) Viewed 2943 times
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- case.sif
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- beam_step.step
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POLYTECHNIC UNIVERSITY OF TURIN-DIMEAS
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Re: HARTMANN PROBLEM
You might start with units, your constants and materials appear to be SI units, so your beam is 1000 meters by 50 meters. Large domains tend not to converge well. If this was supposed to be 1 meter by .05 meter then there is a scaling command that can be used in the sif file, in the Simulation Section.
Coordinate Scaling = 0.001
Coordinate Scaling = 0.001
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Re: HARTMANN PROBLEM
Hi,
I have proved, but it does not converge. Is there any example already developed of this kind of problem?
Regards,
Andrea
I have proved, but it does not converge. Is there any example already developed of this kind of problem?
Regards,
Andrea
POLYTECHNIC UNIVERSITY OF TURIN-DIMEAS
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Re: HARTMANN PROBLEM
Not that I know of, but since you have the mag and the stokes solvers, it is best to specify the boundary conditions for both solvers at every boundary. IS it diverging on the stokes or the mag? I would guess stokes, especially if the velocity is too high.
Boundary Condition 1
Target Boundaries(1) = 4
Name = "potencial wall"
AV {e} 3 = 0.01
AV {e} = 0
End
Boundary Condition 2
Target Boundaries(1) = 2
Name = "wall"
AV {e} = 0
AV = 0
AV {e} 3 = 0
End
Boundary Condition 3
Target Boundaries(1) = 6
Name = "outlet"
External Pressure = 3.97
End
Boundary Condition 4
Target Boundaries(1) = 3
Name = "top"
Noslip wall BC = True
End
Boundary Condition 5
Target Boundaries(1) = 1
Name = "bottom"
Noslip wall BC = True
End
Boundary Condition 1
Target Boundaries(1) = 4
Name = "potencial wall"
AV {e} 3 = 0.01
AV {e} = 0
End
Boundary Condition 2
Target Boundaries(1) = 2
Name = "wall"
AV {e} = 0
AV = 0
AV {e} 3 = 0
End
Boundary Condition 3
Target Boundaries(1) = 6
Name = "outlet"
External Pressure = 3.97
End
Boundary Condition 4
Target Boundaries(1) = 3
Name = "top"
Noslip wall BC = True
End
Boundary Condition 5
Target Boundaries(1) = 1
Name = "bottom"
Noslip wall BC = True
End
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Re: HARTMANN PROBLEM
Yes, it is diverging in stokes solver. I put the boundary conditions like yours.
Andrea
Andrea
POLYTECHNIC UNIVERSITY OF TURIN-DIMEAS
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Re: HARTMANN PROBLEM
How can I impose an external magnetic field in Elmer?
Andrea
Andrea
POLYTECHNIC UNIVERSITY OF TURIN-DIMEAS
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Re: HARTMANN PROBLEM
I just reiterated your BC as an example, what I meant was you need stoke's BCs on all 6 boundaries. Also the pressure is to high for laminar flow. Non-laminar flow often will not have a steady state condition, meaning it will never converge in steady state. This example converges
You can turn beam3d.grd into a mesh with
ElmerGrid 1 2 beam3d.grd
You can turn beam3d.grd into a mesh with
ElmerGrid 1 2 beam3d.grd
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Re: HARTMANN PROBLEM
Thanks for your answer and help. I have run your case but it does not converge. I attached the output file. I didn't understand this:
Andrea
.You can turn beam3d.grd into a mesh with
ElmerGrid 1 2 beam3d.grd
Andrea
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- output.txt
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POLYTECHNIC UNIVERSITY OF TURIN-DIMEAS
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Re: HARTMANN PROBLEM
Convergence can be mesh sensitive as well. The program ElmerGrid converts various formats in an elmer, including and elmer grid file.
To execute the program you use a terminal window or command prompt window and type
ElmerGrid 1 2 beam3d.grd
the program creates a mesh in a folder called beam3d
If you type ElmerGrid with no arguments it lists all of the options.
If you ran my sif with your mesh it may not match up, the type of elements, and boundary numbers were different.
To execute the program you use a terminal window or command prompt window and type
ElmerGrid 1 2 beam3d.grd
the program creates a mesh in a folder called beam3d
If you type ElmerGrid with no arguments it lists all of the options.
If you ran my sif with your mesh it may not match up, the type of elements, and boundary numbers were different.
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Re: HARTMANN PROBLEM
Hi Kevin,
Is it possible applying an external electric field like the magnetic one in Elmer?
Regards,
Andrea
Is it possible applying an external electric field like the magnetic one in Elmer?
Regards,
Andrea
POLYTECHNIC UNIVERSITY OF TURIN-DIMEAS