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Thds Electrostatics coupled convergance problem
Posted 12 janv. 2012, 11:59 UTC−5 5 Replies
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Hi everyone!
I try to simulate a 3D microstructure of a lithium ion battery (just of the anode). I simulate the electrolyte with ionic transport of 2 ion species c_el, c_elA with c_el as positive and c_elA as negative ions. I do that with transport of diluted species with migration in electric field. The source of the electric field is the voltage V_ES which is from an Electrostatics, defined also in the electrolyte region. In this electrostatics I define a space charge density with the value: (c_el-c_elA)*F (F=Faraday constant). That should create my V_ES.
I also define initial values for the 2 concentrations c_el0 = c_elA0 = 1000 mol/m^3 and for the voltage V_ES = 0V
At the open (not to the electrode bordering) side, I define a constant concentration of the positive ions c_el = c_el0 to simulate the constant inflow of that one species of ions (the Li-Ions), and a constant electric potential 0V.
For the connection to the electrode I define a current density j_ct (charge transfer) after the Butler-Volmer equation, with which the charged ions leave the electrolyte and with which uncharged particles enter the electrode material. Therfore I simulate the Electrode material with a transport of diluted species (only one sort of particles now and without migration in an electric field, so uncharged) and an electric current, which leaves the electrode on the other side with a current density of j_L. So j_L should control the running of the battery.
I start the j_L with a step function from 0.1s to 1s.
The problem now is, that the progam starts but the convergence goes up to a scale of 1E8, when the current j_L starts to rise. And it has something to do with the coupling of the transport of diluted species and the electrostatics in the electrolyte. If I deactivate the electrical migration or the space charge density, the program goes through.
Hope somebody can help me
Cheers,
Chris!
By the way I use 4.2a.
I try to simulate a 3D microstructure of a lithium ion battery (just of the anode). I simulate the electrolyte with ionic transport of 2 ion species c_el, c_elA with c_el as positive and c_elA as negative ions. I do that with transport of diluted species with migration in electric field. The source of the electric field is the voltage V_ES which is from an Electrostatics, defined also in the electrolyte region. In this electrostatics I define a space charge density with the value: (c_el-c_elA)*F (F=Faraday constant). That should create my V_ES.
I also define initial values for the 2 concentrations c_el0 = c_elA0 = 1000 mol/m^3 and for the voltage V_ES = 0V
At the open (not to the electrode bordering) side, I define a constant concentration of the positive ions c_el = c_el0 to simulate the constant inflow of that one species of ions (the Li-Ions), and a constant electric potential 0V.
For the connection to the electrode I define a current density j_ct (charge transfer) after the Butler-Volmer equation, with which the charged ions leave the electrolyte and with which uncharged particles enter the electrode material. Therfore I simulate the Electrode material with a transport of diluted species (only one sort of particles now and without migration in an electric field, so uncharged) and an electric current, which leaves the electrode on the other side with a current density of j_L. So j_L should control the running of the battery.
I start the j_L with a step function from 0.1s to 1s.
The problem now is, that the progam starts but the convergence goes up to a scale of 1E8, when the current j_L starts to rise. And it has something to do with the coupling of the transport of diluted species and the electrostatics in the electrolyte. If I deactivate the electrical migration or the space charge density, the program goes through.
Hope somebody can help me
Cheers,
Chris!
By the way I use 4.2a.
5 Replies Last Post 11 avr. 2013, 09:42 UTC−4
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Posted:
1 decade ago
Please somebody...........
By the way, how can I upload my model?
If I do attach file, the green bar starts only one millimeter.
Chris
By the way, how can I upload my model?
If I do attach file, the green bar starts only one millimeter.
Chris
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Posted:
1 decade ago
Hi
for the upload, perhaps youre file is too big, try to Edit clear the solution and or the mesh (and File reset), it will shrink substantially.
--
Good luck
Ivar
for the upload, perhaps youre file is too big, try to Edit clear the solution and or the mesh (and File reset), it will shrink substantially.
--
Good luck
Ivar
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Posted:
1 decade ago
Thanks,
here is my model now, just without my mesh.
Hope it makes clear what I meant.
Chris!
here is my model now, just without my mesh.
Hope it makes clear what I meant.
Chris!
Attachments:
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Posted:
1 decade ago
Hi
unfortunately I do not have all licence modules required so I cannot open correctly the file
--
Good luck
Ivar
unfortunately I do not have all licence modules required so I cannot open correctly the file
--
Good luck
Ivar
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Posted:
1 decade ago
Hello everyone,
I have a convergence problem with modelling of Electrostatics equation coupled with PDE( for charge transport equation). I attached the equations and .mph files.
MODEL : two electrodes placed in domain of air. voltage difference applied. I have to calculate resultant electric field, charge density values and use them to add a body force to laminar flow to simulate plasma.
1. Geometry is simple. Mesh is fine.
2. I tried fully coupled( various damping factors), segregated, parametric sweep of the source term in charge transport equation( which makes it nonlinear) but couldn't get it to converge.
3. I tried using PDEs alone instead of electrostatics,but again same problem ( Plasma Actuator Mod.mph)
Could anyone please help me with way to obtain convergence or any other way to solve the equations attached.
I have a convergence problem with modelling of Electrostatics equation coupled with PDE( for charge transport equation). I attached the equations and .mph files.
MODEL : two electrodes placed in domain of air. voltage difference applied. I have to calculate resultant electric field, charge density values and use them to add a body force to laminar flow to simulate plasma.
1. Geometry is simple. Mesh is fine.
2. I tried fully coupled( various damping factors), segregated, parametric sweep of the source term in charge transport equation( which makes it nonlinear) but couldn't get it to converge.
3. I tried using PDEs alone instead of electrostatics,but again same problem ( Plasma Actuator Mod.mph)
Could anyone please help me with way to obtain convergence or any other way to solve the equations attached.
Attachments: