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Gradient in comsol
Posted 1 déc. 2010, 03:08 UTC−5 2 Replies
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hello,
I'm using comsol for the first time, and I think I've got everything working, except that I need to write a boundary condition that is dependent upon the gradient of a variable. How do I tell Comsol to take the gradient?
v =?k *F*C*?phi/mu
I'm using comsol for the first time, and I think I've got everything working, except that I need to write a boundary condition that is dependent upon the gradient of a variable. How do I tell Comsol to take the gradient?
v =?k *F*C*?phi/mu
2 Replies Last Post 25 mars 2011, 18:40 UTC−4
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Posted:
1 decade ago
Hi
it takes some time to get used to COMSOL 's notation, therefore its very usefull to read a couple of times the doc, but this takes also time ;)
a dependent variable "u" in the spatial cartesian coordinates x,y,z has derivatives named ux=d/dx(u) a "gradient" = [ux, uy, uz] and the "del"=uxx+uyy+uzz
pls note too that COMSOL is working in then cartesian coordinate system and not all operators are coordinate transformed invariant, so if you change you must check when you need to add corrections. COMSOl does allow to define local user coordinates that helps you set up your moel, and allos COMSOL to reconvert back to cartesian
--
Good luck
Ivar
it takes some time to get used to COMSOL 's notation, therefore its very usefull to read a couple of times the doc, but this takes also time ;)
a dependent variable "u" in the spatial cartesian coordinates x,y,z has derivatives named ux=d/dx(u) a "gradient" = [ux, uy, uz] and the "del"=uxx+uyy+uzz
pls note too that COMSOL is working in then cartesian coordinate system and not all operators are coordinate transformed invariant, so if you change you must check when you need to add corrections. COMSOl does allow to define local user coordinates that helps you set up your moel, and allos COMSOL to reconvert back to cartesian
--
Good luck
Ivar
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Posted:
1 decade ago
Hi Ivar,
I go the simulation done but I have some doubt perhas you can give me some advice.
The result of solid.sx and solid.sy are both seems reasonable and appear to be symmetry. However, when I
d(solid.sx,X), the result is no more sysmetry. I was expecting to have symmetry result as well. Could you please give me advice?
Thanks
WK
I go the simulation done but I have some doubt perhas you can give me some advice.
The result of solid.sx and solid.sy are both seems reasonable and appear to be symmetry. However, when I
d(solid.sx,X), the result is no more sysmetry. I was expecting to have symmetry result as well. Could you please give me advice?
Thanks
WK