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Old   June 7, 2011, 05:29
Default change fixedGradient BC during run
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fisch
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Hello,

i want to change my boundary conditions during the run of my solver.
So specifying Dirichlet BC was more or less easy to implement (overwriting the boundaryFields of the variables).

Now I want to overwrite the value of the fixedGradient BC during the runtime for other variables.
Is this possible and easy to access?

Thank you for any advice,

rupert
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Old   June 7, 2011, 10:16
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Bernhard Gschaider
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Quote:
Originally Posted by fisch View Post
Hello,

i want to change my boundary conditions during the run of my solver.
So specifying Dirichlet BC was more or less easy to implement (overwriting the boundaryFields of the variables).

Now I want to overwrite the value of the fixedGradient BC during the runtime for other variables.
Is this possible and easy to access?

Thank you for any advice,

rupert
Use groovyBC? Unless you really want to write your BC in C++
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Old   June 7, 2011, 10:41
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fisch
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thanks bernhard for the quick reply,

there are unfortunately questions left:
Is there no problem using the groovyBC specifying values for "valueExpression" and for "gradientExpression" ???
I thought that it is the only way to specify (e.g. using) simpleFoam either the velocity as dirichlet and the pressure as neumann or the other way around. Now it seems that i can specify on both fields dirichlet and neumann!?

Can you explain that to me?

One more thing: What is, if i dont specify one of these two keywords ( "valueExpression" or "gradientExpression)??

thanks a lot,
rupert
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Old   June 8, 2011, 06:53
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Quote:
Originally Posted by fisch View Post
thanks bernhard for the quick reply,

there are unfortunately questions left:
Is there no problem using the groovyBC specifying values for "valueExpression" and for "gradientExpression" ???
I thought that it is the only way to specify (e.g. using) simpleFoam either the velocity as dirichlet and the pressure as neumann or the other way around. Now it seems that i can specify on both fields dirichlet and neumann!?

Can you explain that to me?
groovyBC is a child class of the mixed-BC. Have a look in the USerGuide for that
Quote:
Originally Posted by fisch View Post
One more thing: What is, if i dont specify one of these two keywords ( "valueExpression" or "gradientExpression)??

thanks a lot,
rupert
That is described here:

http://openfoamwiki.net/index.php/Co...s_in_the_patch
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Old   June 8, 2011, 12:34
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fisch
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Thanks a lot Bernhard,
it seems that it works.

rupert
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