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TCD Electrode Boundary Showing 'Not Applicable' in Aluminum–Air Battery Model
Posted 2026/01/17 16:42 GMT-5 2 Replies
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Hello everyone,
I am currently working on an Aluminum–air battery simulation using the tcd interface in COMSOL.
I am trying to define an Electrode Surface on a specific boundary (Boundary 11). However, when I select this boundary, the setting consistently shows “Not applicable”, even though I believe this boundary should physically represent the electrode–electrolyte interface.
Here is some additional context:
- The model includes aluminum as the anode and an electrolyte domain with ionic transport.
- Boundary 11 is located at the interface between the aluminum solid domain and the electrolyte domain.
- The Electrode Surface node is added under the TCD interface, but Boundary 11 cannot be applied.
I would like to ask:
- Under what conditions would an Electrode Surface boundary be marked as Not applicable in the TCD interface?
- Are there any specific requirements for boundary eligibility when defining an Electrode Surface in aluminum–air battery models?
Any guidance or suggestions on how to properly diagnose and resolve this issue would be greatly appreciated.
Thank you very much for your help.
Best regards, Da-Wei Chen
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I don't have that module (and I don't know much about modeling batteries either) but I can see you are trying to set a boundary condition on an internal surface. In many cases/many physics problems, you will find such a surface to be "not applicable," because the physics you are trying to set doesn't easily apply to (or is ambiguous on) a two-sided surface. However, sometimes Comsol includes more tools to apply conditions to internal surfaces, if/when those conditions can be applied meaningfully.
With that in mind, I noticed you have another option available to you to specify this surface. In the Model Builder, right-click on "Tertiary Current Distribution, Nernst-Planck (tcd)" and then choose "Electrode and Electrolyte Phases" and then choose "Internal Electrode Surface." You can then select Surface #11. Please try that and let us know if this lets you set the physics up the way that you want! Good luck.
Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
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Hi Robert,
Your suggestion works!!! Much appreciated
