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Comsol multiphysics node

Posted Aug 20, 2020, 10:46 p.m. EDT Computational Fluid Dynamics (CFD), Electrochemistry Version 5.3a 5 Replies

Azin Azadi
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Hi there, I am using Comsol 5.3a to couple Darcy eq, transport of dilute solutes and electrostatics together for 3 different solutes (Na, Cl and Albumin). When I am using "Multiphysics" to couple these 3 equs together the results are different with when I turned off the "Multiphysics". I am not sure which result is the reliable one. Based on My prediction, the results hold be similar to when I disable the "Multiphysics". But is that correct to not using "Multiphysics"?

any help much appreciated.

Azin

5 Replies Last Post Sep 7, 2020, 3:32 a.m. EDT
Lasse Murtomäki
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Posted: 4 years ago Aug 25, 2020, 2:16 a.m. EDT

If you simulate transport of charged species, a better option is to use Nernst-Planck equation in, e.g. Tertiary Current Distribution node that computes electric potential in the liquid phase and ionic transport in an electric field. Coupling electrostatic field to tranport is not sufficient because ionic transport has a contribution in the field, i.e. diffusion potential.

If you simulate transport of charged species, a better option is to use Nernst-Planck equation in, e.g. Tertiary Current Distribution node that computes electric potential in the liquid phase and ionic transport in an electric field. Coupling electrostatic field to tranport is not sufficient because ionic transport has a contribution in the field, i.e. diffusion potential.
Azin Azadi
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Posted: 4 years ago Sep 3, 2020, 2:02 a.m. EDT
Updated: 4 years ago Sep 3, 2020, 5:46 a.m. EDT

Thank You for your Answer. However, I need to define the space charge density on part of the domain by using FCD. it is the three layer membrane, and on the middle one there is a (Space charge density) that I need to define. When I start using Nernst-Planck, I could not find any boundary condition to define that Fixed charge density. That is why I try couple electrostatic with solute transport module ( through Nernst-Planck-Poisson) is much better for my problem, which gave me different result with activate/deactivate the Multiphysics. Do ou have any idea, how I can define fixed charged density in Nernst-Planck module? I really appreciate your help,

Thank You for your Answer. However, I need to define the space charge density on part of the domain by using FCD. it is the three layer membrane, and on the middle one there is a (Space charge density) that I need to define. When I start using Nernst-Planck, I could not find any boundary condition to define that Fixed charge density. That is why I try couple electrostatic with solute transport module ( through Nernst-Planck-Poisson) is much better for my problem, which gave me different result with activate/deactivate the Multiphysics. Do ou have any idea, how I can define fixed charged density in Nernst-Planck module? I really appreciate your help,
Lasse Murtomäki
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Posted: 4 years ago Sep 4, 2020, 1:49 a.m. EDT

There is an option Ion Exchange Membrane where you can insert fixed charge density. I am currently using it with success.

Lasse

There is an option Ion Exchange Membrane where you can insert fixed charge density. I am currently using it with success. Lasse
Azin Azadi
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Posted: 4 years ago Sep 6, 2020, 3:30 a.m. EDT

Hi,

Thank you. I am trying to find tertiary node under Nernst-Planck equation, but could not find it. Do you mind let me know where exactly is the tertiary node in Nernst-Planck equ?

Regards,

Hi, Thank you. I am trying to find tertiary node under Nernst-Planck equation, but could not find it. Do you mind let me know where exactly is the tertiary node in Nernst-Planck equ? Regards,
Lasse Murtomäki
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Posted: 4 years ago Sep 7, 2020, 3:32 a.m. EDT

It is under electrochemistry node. Do you have it?

Lasse

It is under electrochemistry node. Do you have it? Lasse

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