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Periodic Boundary Condition for Boundary PDE

Posted Sep 13, 2023, 9:31 a.m. EDT Modeling Tools & Definitions, Equation-Based Modeling, Physics Interfaces Version 6.0 1 Reply

Giuliano Lombardo
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Hello all,

I would like to solve a mathematical problem on a surface in 3D. For this I have used "Coefficient Form Boundary PDE". Now I need a periodic boundary condition between two opposite edges. I tried to solve it manually using Dirichet and Flux/Source, but the boundary condition is always overwritten by the other one.

Does anyone of you have a solution for this problem.

Thanks a lot!

Best,

Giuliano Lombardo

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1 Reply Last Post Sep 15, 2023, 6:29 a.m. EDT
Nils Malm COMSOL Employee

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Posted: 7 months ago Sep 15, 2023, 6:29 a.m. EDT
Updated: 7 months ago Sep 15, 2023, 6:29 a.m. EDT

Dear Giuliano Lombardo,

Unfortunately, boundary-level PDE interfaces do not directly support periodic boundary conditions at this point. But you can set the condition up manually. You will first need to define a General Extrusion operator that maps values from the source edge to the target edge. Once you have this operator set up and tested so that you can evaluate something like genext1(ws) on the target edge, you can move on to the constraint. On the target edge, you simply have to set a constraint of the form genext1(ws)-ws. The default constraints settings will apply reaction fluxes symmetrically on source and target, which will lead to continuity in both value and flux. That is, you do not have to enforce flux continuity separately.

Best regards,

Nils Malm

Dear Giuliano Lombardo, Unfortunately, boundary-level PDE interfaces do not directly support periodic boundary conditions at this point. But you can set the condition up manually. You will first need to define a General Extrusion operator that maps values from the source edge to the target edge. Once you have this operator set up and tested so that you can evaluate something like *genext1(ws)* on the target edge, you can move on to the constraint. On the target edge, you simply have to set a constraint of the form *genext1(ws)-ws*. The default constraints settings will apply reaction fluxes symmetrically on source and target, which will lead to continuity in both value and flux. That is, you do not have to enforce flux continuity separately. Best regards, Nils Malm

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