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PDE in tensor notation and converting in weak form.
Posted Dec 25, 2016, 3:49 a.m. EST Version 5.2 3 Replies
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Hi,
I am a new user in comsol and a novice in equation modelling. I am working with an equation with tensor notation. I want to model it in comsol. However, due to the notation I am not understanding how to work with it. I started with some basic PDEs like heat and wave and successfully modelled them. But, this equation is something I am not understanding how to handle it. Specifically, I want to convert it in weak form at the end. But, now I just want to model it as it is. Please, help me with some reading materials. Thanks.
I am a new user in comsol and a novice in equation modelling. I am working with an equation with tensor notation. I want to model it in comsol. However, due to the notation I am not understanding how to work with it. I started with some basic PDEs like heat and wave and successfully modelled them. But, this equation is something I am not understanding how to handle it. Specifically, I want to convert it in weak form at the end. But, now I just want to model it as it is. Please, help me with some reading materials. Thanks.
3 Replies Last Post Dec 31, 2016, 11:43 p.m. EST
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Posted:
8 years ago
Hi,
I am sending the equations as well. The unknowns are T, pw and u.
TIA
I am sending the equations as well. The unknowns are T, pw and u.
TIA
Attachments:
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Posted:
8 years ago
Hi,
You have a coupled thermo-poro-elastic problem - so three governing equations.
I do not see why you want to take the trouble of using the weak form. Why not use the readily available COMSOL modules?
COMSOL has all the three components in-built:
a) if you click on poroelasticity module, it will load up Darcy's law (2nd equation) and linear elastic model (plane strain if 2D otherwise 3D) (first equation). Note that the three terms of your first equation is linear elasticity, thermal expansion and Biot's pressure term, respectively. All are available in poroelasticity module. For your second equation, the Darcy's law node and the multiphysics node (that automatically appears when you select poroelasticity) will handle it.
b) you can then select "heat transfer in porous media", so you have your third equation. Because you have an extra term (second term on RHS), which I guess is the latent heat term, you just have to select phase change material and make appropriate choices.
It may take you a while but I believe you should be able to get through it. The most important thing is to ensure that all your terms matches with COMSOL equation view.
Suresh
You have a coupled thermo-poro-elastic problem - so three governing equations.
I do not see why you want to take the trouble of using the weak form. Why not use the readily available COMSOL modules?
COMSOL has all the three components in-built:
a) if you click on poroelasticity module, it will load up Darcy's law (2nd equation) and linear elastic model (plane strain if 2D otherwise 3D) (first equation). Note that the three terms of your first equation is linear elasticity, thermal expansion and Biot's pressure term, respectively. All are available in poroelasticity module. For your second equation, the Darcy's law node and the multiphysics node (that automatically appears when you select poroelasticity) will handle it.
b) you can then select "heat transfer in porous media", so you have your third equation. Because you have an extra term (second term on RHS), which I guess is the latent heat term, you just have to select phase change material and make appropriate choices.
It may take you a while but I believe you should be able to get through it. The most important thing is to ensure that all your terms matches with COMSOL equation view.
Suresh
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Posted:
8 years ago
Hi,
I want to do the equation based modelling because I have some more models and I want to have a generalised method to model them in comsol. And these are modified equations and I dont know how to implement these equations by the ready-made physics modules.
I want to do the equation based modelling because I have some more models and I want to have a generalised method to model them in comsol. And these are modified equations and I dont know how to implement these equations by the ready-made physics modules.