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March 15, 2012, 13:32 |
Table defined BC
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#1 |
Senior Member
Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
Rep Power: 17 |
Is it possible to define a patch using its caracteristic data ?
For example, on an outlet we could know the p/U relation: p=0.1bar ---> U=0.1l/s p=0.5bar ---> U=0.4l/s p=1.0bar ---> U=0.7l/s .... It would be usefull in complex system. You can avoid simulating external part already characterized. Can this be implemented ? Daniele |
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March 15, 2012, 13:58 |
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#2 |
Senior Member
Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
Rep Power: 17 |
Sorry to make questions before deep searching.
I think the best thing is to use groovyBC in following way. Let's say we approximate the p/U relation with: U=p/10+5 (note: just a random linear relation) and the outlet flow is just in the x direction, then: For 0/U: Code:
outlet { type groovyBC; variables "Ux=p/10+5"; valueExpression "vector(Ux,0,0)"; value uniform (0 0 0); } Daniele |
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March 15, 2012, 14:38 |
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#3 | |
Assistant Moderator
Bernhard Gschaider
Join Date: Mar 2009
Posts: 4,225
Rep Power: 51 |
Quote:
In the variables-string a ; is missing The valueExpression might be more elegant if you write it like "Ux*normal()". That way it works no matter how the boundary is oriented (not 100% sure. You might night a - there) Concerning your original posting: expressions in swak4Foam can have lookup-tables where you specify a function by value pairs and values are interpolated between these. For an exmple on the usage see the wobbler-case in the examples |
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March 15, 2012, 14:40 |
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#4 |
Senior Member
mauricio
Join Date: Jun 2011
Posts: 172
Rep Power: 17 |
it's hard, at least of me, to say.. but is your simulation ss or transient? i kinda of a need a very specific reason b4 implementing things.. so i can't tell..
as for stability.,, i guess you cannot fix pressure and flowrate, U, at the same patch and model.... so i guess you got pick one var to fix..
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Best Regards /calim "Elune will grant us the strength" |
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March 15, 2012, 16:17 |
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#5 |
Senior Member
Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
Rep Power: 17 |
Many thanks ! Sure, I know fixing an outlet U is problematic. I'll make some simple bc tests and report here.
daniele |
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