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Calculation of dependent variables at boundary conditions
Posted Jun 27, 2017, 9:01 a.m. EDT 1 Reply
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Hello everyone,
I have a model where I am simulating heat transfer in soils.
The question is:
As I have the dependent variable T also as a boundary condition, for instance, convective heat in the surface is q=h(Text-T), how can I be sure that Comsol does sufficient computation for a precise value, or yet if Comsol could perform less computation to save time? Has it something to do with the number of iterations?
Thanks in advance
I have a model where I am simulating heat transfer in soils.
The question is:
As I have the dependent variable T also as a boundary condition, for instance, convective heat in the surface is q=h(Text-T), how can I be sure that Comsol does sufficient computation for a precise value, or yet if Comsol could perform less computation to save time? Has it something to do with the number of iterations?
Thanks in advance
1 Reply Last Post Jun 28, 2017, 1:56 a.m. EDT
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Posted:
7 years ago
Hi,
The fact that the dependent variable is part of the boundary condition does not make any fundamental changes to the problem. h*Text ends up in the right hand side, and h*T in the stiffness matrix.
Your example (convection) is a linear boundary condition, so there would not be any iterations anyway. For a radiation condition q=a*(Text^4-T^4), the problem would become nonlinear, and then you, as for any nonlinear problem, will have an accuracy which is controlled by the tolerance settings.
Regards,
Henrik
The fact that the dependent variable is part of the boundary condition does not make any fundamental changes to the problem. h*Text ends up in the right hand side, and h*T in the stiffness matrix.
Your example (convection) is a linear boundary condition, so there would not be any iterations anyway. For a radiation condition q=a*(Text^4-T^4), the problem would become nonlinear, and then you, as for any nonlinear problem, will have an accuracy which is controlled by the tolerance settings.
Regards,
Henrik