How to implement equations for simulation of DC current

tjliang · April 21, 2015, 16:56

Hello Foamers,

I want to simulate the electric potential within a electrode, whose Current is DC mode, 30A,but at the tip the sectional area becomes much smaller.

I have tried setting the gradient of potential at the top to be like -j/sigma. I wonder :

1. which equations to be implemented for calculating potential.

2. which type of boundary condition to be set for potential at the other electrode surface.

Thanks ,

Peng

chriss85 · April 23, 2015, 03:51

The equation you want to solve is laplace(sigma, phi) = 0.
Then E = - grad(phi) and j = sigma * E.
You can either set the potential as fixedValue boundary condition for phi or specify a current by using a fixed gradient with -j/sigma.

batteryFoamer · October 13, 2022, 22:58

Quote:

Originally Posted by tjliang

Hello Foamers,

I want to simulate the electric potential within a electrode, whose Current is DC mode, 30A,but at the tip the sectional area becomes much smaller.

I have tried setting the gradient of potential at the top to be like -j/sigma. I wonder :

1. which equations to be implemented for calculating potential.

2. which type of boundary condition to be set for potential at the other electrode surface.

Thanks ,

Peng

Hi Peng, I have the same question for a long time. Have you solved this question? really really thank you

LongGe · October 14, 2022, 00:45

Hi All

Does this functionObject "OpenFOAM/OpenFOAM-v2206/src/functionObjects/solvers/electricPotential" not match your requirements?

tutorial: OpenFOAM/OpenFOAM-v2206/tutorials/multiphase/interFoam/RAS/electrostaticDeposition
See: https://www.openfoam.com/documentati...l.html#details

chriss85 · October 14, 2022, 01:20

$\nabla \sigma \nabla \phi = 0$
As long as the medium has a significantly lower conductivity compared to the electrodes, you can prescribe the electric potential at the electrodes and calculate the resulting current as $-\sigma \nabla \phi$ .

batteryFoamer · October 14, 2022, 03:36

Quote:

Originally Posted by LongGe

Hi All

Does this functionObject "OpenFOAM/OpenFOAM-v2206/src/functionObjects/solvers/electricPotential" not match your requirements?

tutorial: OpenFOAM/OpenFOAM-v2206/tutorials/multiphase/interFoam/RAS/electrostaticDeposition
See: https://www.openfoam.com/documentati...l.html#details

Hi
this is a steady-state equation. as you know, since the internal resistance, our poisson's equation has a source term which changes with time.and you can refer this paper(Theoretical Analysis of Potential and Current Distributions in Planar Electrodes of Lithium-ion Batteries), so we don't know how to solve the question in the negative and positive electrode.

batteryFoamer · October 14, 2022, 03:40

Quote:

Originally Posted by chriss85

$\nabla \sigma \nabla \phi = 0$
As long as the medium has a significantly lower conductivity compared to the electrodes, you can prescribe the electric potential at the electrodes and calculate the resulting current as $-\sigma \nabla \phi$ .

Thank you for your help!

but in NTGK model of battery, there is a type of ion current J in the poisson equation. we want to set this model in the OF.

chriss85 · October 14, 2022, 09:43

The equation I mentioned is only for classical steady-state current without surface charges and with quasi-neutrality. If you have charge distributions you may have to model the charge carrier drift somehow. I'm afraid I can't help with that very much.

April 21, 2015, 16:56	How to implement equations for simulation of DC current	#1
tjliang Member Peng Liang Join Date: Mar 2014 Posts: 59 Rep Power: 12	Hello Foamers, I want to simulate the electric potential within a electrode, whose Current is DC mode, 30A,but at the tip the sectional area becomes much smaller. I have tried setting the gradient of potential at the top to be like -j/sigma. I wonder : 1. which equations to be implemented for calculating potential. 2. which type of boundary condition to be set for potential at the other electrode surface. Thanks , Peng Andrew_ding likes this.

October 14, 2022, 00:45		#4
LongGe Member Tatsuya Shimizu Join Date: Jul 2012 Posts: 42 Rep Power: 13	Hi All Does this functionObject "OpenFOAM/OpenFOAM-v2206/src/functionObjects/solvers/electricPotential" not match your requirements? tutorial: OpenFOAM/OpenFOAM-v2206/tutorials/multiphase/interFoam/RAS/electrostaticDeposition See: https://www.openfoam.com/documentati...l.html#details __________________ Our Work: https://www.idaj.co.jp/product/ennovacfd/openfoam_gui/ Powered by Ennova : https://ennova-cfd.com/ Ennova's Channel Partners : http://www.wolfdynamics.com/

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April 23, 2015, 03:51		#2
chriss85 Senior Member Join Date: Oct 2013 Posts: 397 Rep Power: 18	The equation you want to solve is laplace(sigma, phi) = 0. Then E = - grad(phi) and j = sigma * E. You can either set the potential as fixedValue boundary condition for phi or specify a current by using a fixed gradient with -j/sigma.

October 14, 2022, 01:20		#5
chriss85 Senior Member Join Date: Oct 2013 Posts: 397 Rep Power: 18	$\nabla \sigma \nabla \phi = 0$ As long as the medium has a significantly lower conductivity compared to the electrodes, you can prescribe the electric potential at the electrodes and calculate the resulting current as $-\sigma \nabla \phi$ .

October 14, 2022, 09:43		#8
chriss85 Senior Member Join Date: Oct 2013 Posts: 397 Rep Power: 18	The equation I mentioned is only for classical steady-state current without surface charges and with quasi-neutrality. If you have charge distributions you may have to model the charge carrier drift somehow. I'm afraid I can't help with that very much.