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surface integration of a derived temperature distribution
Posted Jun 11, 2020, 6:50 a.m. EDT Mesh, Results & Visualization Version 5.4 2 Replies
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I have just started learning COMSOL and have a problem now.
I derived the surface temperature distribution of a sphere using COMSOL.
After that, I calculated the net radiation force of the sphere, i.e. the surface integrations of 
, where 
is the temperature and 
is the unit normal vector.
However, the result of surface integrations given by COMSOL seems to be incorrect.
Then I did another test with a uniform surface temperature distribution. The result of surface integrations should be zero in theory due to the symmetry, but it is in fact not. I am confused now. Is there something wrong about the surface integration function in COMSOL?
I would appreciate it if someone offers some help.
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Hello xy b,
There integrations are performed numerically on a mesh, so while in theory the integral of the normal vector on a sphere is zero when you compute it on a mesh (which does not exactly match the sphere's surface and is not necessarily symmetric) the computed value will generally not be zero. It will tend to zero as you refine the mesh.
Best regards,
Jeff
-------------------Jeff Hiller
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Hello Jeff,
Glad to receive your reply. Thank you so much for your explanation.
Best regards,
Yang-Bo Xu