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I have two question.

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I would like to ask:
- Whether it is possible to delete a variable from the list of dependent variables?
- Or bothers the model physics, which is not fully defined.

and thank for typ
compute to with one depended variable only.

Thank verry much.

1 Reply Last Post 10 gen 2012, 13:36 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 10 gen 2012, 13:36 GMT-5
Hi

from my knowledge the predefined physics are made with the minimum of dependent variables to be coherent, so you cannot supress any without consequences. You could try to keep one constant, provided it is coherent with the overall equations.
However, many physics allows to add more dependent variables, to add extra and new phenomeny, and some such as the HT have two set of independent dependent variables i.e. the radition terms that remain at "0" if not used.

What you can always do is to use the default math PDE and solve for the number of dependet variables you want, provied that your set of equations remain coherent (mathematically and defined uniquely with only 1 valid solution).

Reminder: many PDE have several families of solutions dependeing on the BC's you choose, that is why one need to define enough BC's to avoid any duplification of solutions, or bifucations in the solutions, there COMSOL cannot decide to turn "left" or "right" without some clever guiding by the user

--
Good luck
Ivar
Hi from my knowledge the predefined physics are made with the minimum of dependent variables to be coherent, so you cannot supress any without consequences. You could try to keep one constant, provided it is coherent with the overall equations. However, many physics allows to add more dependent variables, to add extra and new phenomeny, and some such as the HT have two set of independent dependent variables i.e. the radition terms that remain at "0" if not used. What you can always do is to use the default math PDE and solve for the number of dependet variables you want, provied that your set of equations remain coherent (mathematically and defined uniquely with only 1 valid solution). Reminder: many PDE have several families of solutions dependeing on the BC's you choose, that is why one need to define enough BC's to avoid any duplification of solutions, or bifucations in the solutions, there COMSOL cannot decide to turn "left" or "right" without some clever guiding by the user -- Good luck Ivar

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