# Yes-No question about poiseuille flow

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 December 29, 2011, 11:42 Yes-No question about poiseuille flow #1 Member   Amin Shariat KHah Join Date: Apr 2011 Location: Shiraz Posts: 86 Rep Power: 15 Dear Foamers, I have read every posts about pressure driven flow but finally I need some one only tell me is it right my conclusion about pressure boundary condition in poiseuille flow, or not: if we have a pressure driven flow and we don't know about velocity but we know pressure boundary condition, we use velocity (U/0) in this form: inlet : type pressureInletVelocity value uniform(0 0 0 ) ; outlet: type zerogradient and pressure as below: inlet: type fixedValue; value uniform 1; (we assume 1 is value of pressure at inlet) outlet type fixedValue; value uniform 0; And another queation, is this pressure value, real or divided by density?

 December 29, 2011, 12:15 #2 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,266 Blog Entries: 1 Rep Power: 24 hi dear Amin please look at the dimension of your pressure file! in 0 folder then you will find whether it is real pressure or divided by rho! amin144 likes this.

 December 29, 2011, 12:37 #3 Member   Amin Shariat KHah Join Date: Apr 2011 Location: Shiraz Posts: 86 Rep Power: 15 Dear Nmia Thanks very much dadash Is the boundary conditions right?

 December 29, 2011, 13:30 #4 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,266 Blog Entries: 1 Rep Power: 24 yep it seems right amin144 likes this.

 December 29, 2011, 14:33 Fan boundary Condition #5 Member   Amin Shariat KHah Join Date: Apr 2011 Location: Shiraz Posts: 86 Rep Power: 15 I've heard about some boundary condition which name is FAN , any body know different between fan and pressureInletVelocity? Is it possible to use it in poiseulle flow?

 January 1, 2012, 05:38 #6 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,266 Blog Entries: 1 Rep Power: 24 fan is periodic boundary condition with a pressure difference between to cyclic face, i suggest you to look at channelIcoFoam, if you want to cyclic boundary condition, however you can use Fan for pressure driven flow! amin144 likes this.

 January 2, 2012, 12:31 #7 Member   Amin Shariat KHah Join Date: Apr 2011 Location: Shiraz Posts: 86 Rep Power: 15 Thanks Dear Nima, have you any idea about it that how can I understand what OpenFoam Code do, when we use one of any boundary conditions?

 January 2, 2012, 13:24 #8 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,266 Blog Entries: 1 Rep Power: 24 1) there is a little description about each code in .C files, you can look at it 2) search in forum about solver 3) look at OpenWiki 4)chalmarse university maybe you find some extra tutorials amin144 likes this.

 January 10, 2012, 06:10 #9 Member   Amin Shariat KHah Join Date: Apr 2011 Location: Shiraz Posts: 86 Rep Power: 15 Thanks very much Dear Nima

 Tags boundary condition, poiseuille flow, pressure driven