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Higher Order Spacial Derivatives

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Greetings,
I am having problems with using higher order spacial derivatives.
For example, I have the first order y derivative of a function c : cy.
It is clear from the attached picture that the second order derivative of cyx is not zero and yet when I plot cyx I get exactly zero. I don't understand what is wrong.
I saw that are previous threads on the subject yet I didn't understand the given explanations.

Also, while searching for a solution to this problem, that there is another kind of derivative defined in the manual:
uTx.
(Tangential derivative?
What is the difference between this and ux?

If i want to define a boundary condition that is dependent on c1 for another variable, say, c2, how do I write it?

cwall2=c1yx/cx

or

cwall2=c1Tyx/cx

or
in another manner?

Thanks in advance.
Yoav


0 Replies Last Post 24 mag 2012, 14:29 GMT-4
COMSOL Moderator

Hello Yoav Green

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