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April 19, 2013, 14:51 |
Boundary
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#1 |
New Member
Aria
Join Date: Nov 2012
Posts: 5
Rep Power: 13 |
Hi everybody,
I am writing a solver for concentration diffusion. Somehow I need to set a boundary condition for concentration so that instead of a fixedValue for a wall, the value at the wall could have a new value after each time step and the value is the average of for example concentration (concentration has already been solved in solver). what type of boundary type should i use and how? thanks |
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April 19, 2013, 15:51 |
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#2 |
Senior Member
Lieven
Join Date: Dec 2011
Location: Leuven, Belgium
Posts: 299
Rep Power: 22 |
Hi Aria,
Is it the scalar transport (convection-diffusion) equation that you are solving? If so, I would advise you to pick a zeroGradient BC. This prevents any diffusion over the wall boundary from occurring. Cheers, L |
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April 20, 2013, 10:03 |
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#3 |
New Member
Aria
Join Date: Nov 2012
Posts: 5
Rep Power: 13 |
Hi,
Thanks for your fast reply, Yes, thats what i solve, but the particel at surface has to be renewed after each five second with a concentration equal to average one. Thats why i need a flexible BC. |
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April 21, 2013, 03:13 |
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#4 |
Senior Member
Lieven
Join Date: Dec 2011
Location: Leuven, Belgium
Posts: 299
Rep Power: 22 |
Hi Aria,
The boundary condition you want to impose is not really clear to me. Do you have a mathematical expression for it to clearify it? E.g. the five seconds, is this equal to the preset time step? Cheers, L |
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April 22, 2013, 08:16 |
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#5 |
Senior Member
Olivier
Join Date: Jun 2009
Location: France, grenoble
Posts: 272
Rep Power: 17 |
hello,
Take a look at groovyBC: you can use a mixed BC (zeroGradient/value), and switch with the expression value you want (like every 5 s), and calculate the average concentration you need. NB: And like Lieven say, take care when you use fixedValue, since you have no control over the diffusive flux. regards, olivier |
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