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How to find gradient in COMSOL 4.1

Chamila Siyambalapitiya

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I want to write my own equation in "derived value" expression field. What function should I use to find 'Grad' of a function.

1 Reply Last Post Jan 10, 2011, 3:48 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago Jan 10, 2011, 3:48 a.m. EST
Hi

it depends on which variable, COMSOL has many internal derivatives defind (note the varible notation if u,v,w are dependent variables ux is du/dx, ut = du/dt, utt=d^2u/dt^2 etc. There is no GRAD operator, but you can wrie it out fully with the (ux,uy,uz)

Check the doc, perhaps the 3.5a doc is still more complete on this, or take some of the books , the one of Zimmermann is my preferred for learning how to do math/equation writin with COSMOL

At least read the 4.1 doc aoround p 100 of the user manual on the variables

--
Good luck
Ivar
Hi it depends on which variable, COMSOL has many internal derivatives defind (note the varible notation if u,v,w are dependent variables ux is du/dx, ut = du/dt, utt=d^2u/dt^2 etc. There is no GRAD operator, but you can wrie it out fully with the (ux,uy,uz) Check the doc, perhaps the 3.5a doc is still more complete on this, or take some of the books , the one of Zimmermann is my preferred for learning how to do math/equation writin with COSMOL At least read the 4.1 doc aoround p 100 of the user manual on the variables -- Good luck Ivar

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