# Pressure averaging at the outlets.

 Register Blogs Members List Search Today's Posts Mark Forums Read

 November 21, 2007, 13:47 Pressure averaging at the outlets. #1 KM Guest   Posts: n/a Hi there, For pressure specified outlet boundary conditions, fluent has one option 'Radial equilibrium pressure distribution'. While CFX-11 seems to have two options for the Pressure Averaging at the pressure outlets. 1) Average Over Whole Outlet 2) Circumferential. Is 'Circumferential averaging' in CFX equivalent to 'Radial equilibrium pressure distribution' in Fluent? I woould be very much thankful to you for your help ! Many Thanks, Best Regards, KM.

 November 21, 2007, 17:42 Re: Pressure averaging at the outlets. #2 CycLone Guest   Posts: n/a Hi KM, With a Radial Equilibrium boundary condition, the specified pressure applies only to the position of minimum radius (relative to the axis of rotation) at the boundary. The static pressure on the rest of the zone is calculated from the assumption that radial velocity is negligible, so that the pressure gradient is given by dp/dr = rho*v_theta^2/r The Average Static Pressure boundary condition solves for the static pressure implicitely and will acheive an equilibrium static pressure profile. In the limit of zero radial velocity and swirling flow this is equivalent to radial equilibrium. A radial equilibrium static pressure profile is better than a fixed static pressure at swirling outlets, but it is still explicit and will result in a non-physical static pressure profile at the outlet. The CFX equivalent would be to specify the Static Pressure as an radial equilibrium expression (i.e. integrate the above equation), but I would suggest using the Average Static Pressure condition instead. Other options: 1) Average over the whole outlet: The pressure is allowed to float over the whole outlet, or you can specify a specific region over which to evaluate the area averaged static pressure. There is no equivalent of this in Fluent 2) Circumferential: If this option is picked you will need to specify a one dimenstional spanwise profile. The solver will match/fix the circumferentially averaged pressure at each location, but allows the circumferential profile to float. A single value just means the circumferentially averaged profile is constant. There is no equivalent to this in Fluent. Note that similar options are available for Mass Flow specified outlets. The default for Mass Flow outlets is also to let the static pressure and local mass flux to float, but match the specified mass flow. Options are also available to shift a pressure profile at a mass flow outlet, circumferentially match a pressure profile, etc. -CycLone

 November 23, 2007, 14:50 Re: Pressure averaging at the outlets. #3 KM Guest   Posts: n/a Dear CycLone, Thank you very much for helping me again with your detailed reply. It helps a lot. Many Thanks, KM.

 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 a.lynchy FLUENT 3 March 23, 2012 14:45 engahmed FLUENT 0 July 6, 2010 17:19 engahmed Main CFD Forum 0 June 16, 2010 11:38 Antech Main CFD Forum 0 April 25, 2006 02:15 tania FLUENT 11 March 23, 2004 09:51

All times are GMT -4. The time now is 12:00.