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[Solved] Dependent Variable Field in The Pressure Acoustics, Time Explicit (pate) also discontinuous Galerkin method?

Posted 27 feb 2025, 07:52 GMT-5 Acoustics & Vibrations, Modeling Tools & Definitions, Physics Interfaces Version 6.3 2 Replies

Sebastian Müller
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Hello!

When using a 'Dependent Variable Field' directly in the 'The Pressure Acoustics, Time Explicit (pate)'* physics interface, will this new extra dependent variable (from 'Dependent Variable Field') also be calculated with the discontinuous Galerkin method (dG-FEM)?? When for example using 'Dependent Variable Field' for a domain.

*which uses discontinuous Galerkin method (dG-FEM) for the standard dependent variables

Nice greetings

2 Replies Last Post 3 mar 2025, 03:33 GMT-5
Sebastian Müller
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Posted: 7 months ago 27 feb 2025, 18:17 GMT-5

Solved: Shape-Functions are generally choosable.

Nice Greetings

Solved: Shape-Functions are generally choosable. Nice Greetings
Kirill Shaposhnikov COMSOL Employee

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Posted: 6 months ago 3 mar 2025, 03:33 GMT-5

Hi Sebastian,

I don't know your exact intention for adding an extra shape there; I just want to mention one important thing. The time-explicit DG-FEM interfaces, like Pressure Acoustics, Time Explicit, are based on a conservation law that is solved in a quadrature-free manner, thus not involving any weak expressions. And there is no way to add an extra shape to the flux term of the conservation law the physics interface is based on. That is, if your conservation law reads "dA(u)/dt + dF(u)/dx = f", you will not be able to add the DOF 'v' to modify it to "dB(u, v)/dt + dG(u, v)/dx = g".

On the other hand, it is possible to have the DOF 'v' contributing to the right-hand side and being connected to 'u' through a weak contribution. For example, this is how the electrostatics DOFs are connected to the elastic DOFs when modelling piezoelectricity with the Elastic Waves, Time Explicit interface: the elastic DOFs (strain, velocity) enter the flux of the conservation law, while the electric potential doesn't.

Best regards Kirill

Hi Sebastian, I don't know your exact intention for adding an extra shape there; I just want to mention one important thing. The time-explicit DG-FEM interfaces, like Pressure Acoustics, Time Explicit, are based on a conservation law that is solved in a quadrature-free manner, thus not involving any weak expressions. And there is no way to add an extra shape to the flux term of the conservation law the physics interface is based on. That is, if your conservation law reads "dA(u)/dt + dF(u)/dx = f", you will not be able to add the DOF 'v' to modify it to "dB(u, v)/dt + dG(u, v)/dx = g". On the other hand, it is possible to have the DOF 'v' contributing to the right-hand side and being connected to 'u' through a weak contribution. For example, this is how the electrostatics DOFs are connected to the elastic DOFs when modelling piezoelectricity with the Elastic Waves, Time Explicit interface: the elastic DOFs (strain, velocity) enter the flux of the conservation law, while the electric potential doesn't. Best regards Kirill

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