inlet/outlet boundary conditions for a forced flow in a channel

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 September 12, 2011, 09:38 inlet/outlet boundary conditions for a forced flow in a channel #1 New Member   Davide Cagnoni Join Date: Jul 2011 Posts: 14 Rep Power: 8 hi! I'm trying to run a simulation about an internal flow in a converging channel, and i am in doubt about the boundary conditions to use: i do not have a fixed mass-flow rate since what i am investigating is the result of a volume force on the fluid flow (therefore i have a source term in the momentum equation...) this force should (and does) pump the fluid towards the narrower section (which is my "outlet") at which i imposed a 0 pressure - 0 stress boudary condition. At first i have imposed the same BC on the other channel edge since i thought the inflow should be free from stress and also at the same "external" pressure - being the motion triggered only by the volume force to which the fluid is exposed - but being my results quite different from what i expected i think something in my opinions is wrong... thanks for every hint anybody would give me

 September 13, 2011, 03:41 #2 New Member   Davide Cagnoni Join Date: Jul 2011 Posts: 14 Rep Power: 8 sorry for bumping....

 September 13, 2011, 08:33 #3 Member   Zachariah Swetky Join Date: Aug 2011 Posts: 36 Rep Power: 8 davide_c, It seems to me that applying a force to the fluid should yield a pressure gradient from the inlet to the outlet. By applying 0 pressure at both the inlet and the outlet are you not nullifying this gradient? Are you specifying total pressure or static pressure at the inlet and outlet?

 September 13, 2011, 09:03 #4 New Member   Davide Cagnoni Join Date: Jul 2011 Posts: 14 Rep Power: 8 If i am correct, my pressure object represents static pressure (normalized by the density) I spent some time thinking about it and realised the same conclusion about the pressure drop, so I switched the pressure condition on inlet to 0-gradient. Still, with this other arrangement i have problems -instabilities- after some time at the outlet. I am thinking about imposing a 0 gradient condition on the whole boundary - which I know phisically not having much sense together wit a no stress condition for U - just to try out...

 Tags boundary, channel, forced, inlet

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Tom Main CFD Forum 7 August 26, 2014 05:58 nzy102 OpenFOAM Running, Solving & CFD 0 April 19, 2007 16:13 yan FLUENT 0 July 4, 2005 23:36 Tudor Miron CFX 15 April 2, 2004 06:18 Ray Main CFD Forum 4 July 29, 2002 09:08

All times are GMT -4. The time now is 05:30.

 Contact Us - CFD Online - Privacy Statement - Top