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More services...Enforcing variables to be greater than or equal to zero
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2 Replies
Last post: December 3, 2012 3:19pm UTC
December 2, 2012 11:29pm UTC
Enforcing variables to be greater than or equal to zero
Hello,
I'm modelling diffusion through a porous medium with adsorption. The main dependent variable for mass concentration tends to go below zero which is not true in reality. Is there a way to enforce my variables to be >=0 at all times?
I would also like to apply this condition to other concentrations that I specify in my additional variables.
Any suggestions would be greatly appreciated.
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December 3, 2012 3:13pm UTC in response to Alistair Kirk
Re: Enforcing variables to be greater than or equal to zero
Alistair,
To enforce variables to be >=0 at all times, use Segregated solver. Then, right-click Segregated 1 node and add Lower Limit node. In the Settings window for Lower limit, you can define lower limits for your field variables.
Good luck,
Sergei Yushanov
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December 3, 2012 3:19pm UTC in response to Alistair Kirk
Re: Enforcing variables to be greater than or equal to zero
Hi
normally it's far better to understand why you get "non physical values"
Mostly it's because of non physical initial conditions or inappropriate meshing densities around steep dependent variable values, once these are corrected the solution is far more robust
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Good luck
Ivar
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