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Deravites in 2D-axisymmetric models
Posted Mar 31, 2013, 2:32 p.m. EDT Low-Frequency Electromagnetics Version 4.3 1 Reply
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Hi guys,
I was wondering if we should add any extra parts for calculating the derivative of a variable in 2D-axisymmetric models? Under Definition ----Variables--If the goal is to define a new variable based on the derivative of the default variable like electric field (E), does this work or not?
new = d(es.Er , r )
Is this correct in axi-symmetric models ? our new variable is now the derivative of the E with respect to r?
I was wondering if we should add any extra parts for calculating the derivative of a variable in 2D-axisymmetric models? Under Definition ----Variables--If the goal is to define a new variable based on the derivative of the default variable like electric field (E), does this work or not?
new = d(es.Er , r )
Is this correct in axi-symmetric models ? our new variable is now the derivative of the E with respect to r?
1 Reply Last Post Apr 1, 2013, 4:17 p.m. EDT
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Posted:
1 decade ago
Hi
it is possible to do it that way, if COMSOL has not already defined a Err) but you might get only "0" out as if you derive many times, you need to ensure that our dependent variables are resolved with higher order discretization (at least one more than the number of sucessive derivatives used)
Sometimes its better to define new global PDEs and define new variables for the elements higher than 2nd derivatives, and not the way to derive continuosly the exsiting ones
--
Good luck
Ivar
it is possible to do it that way, if COMSOL has not already defined a Err) but you might get only "0" out as if you derive many times, you need to ensure that our dependent variables are resolved with higher order discretization (at least one more than the number of sucessive derivatives used)
Sometimes its better to define new global PDEs and define new variables for the elements higher than 2nd derivatives, and not the way to derive continuosly the exsiting ones
--
Good luck
Ivar