CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum

out flow conditions

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

LinkBack Thread Tools Display Modes
Old   February 26, 2008, 23:52
Default out flow conditions
Posts: n/a
I am trying to define the boundary conditions for the outflow boundary of a supersonic impinging jet. I tried using non-reflecting B.C. (sponge layer and characteristic approach) but there still appears to be reflections. if the outflow is supersonic would it be easier just to extrapolate from the interior? i am using Yee's(JCP 88:1990) upwind TVD schemes.

  Reply With Quote

Old   February 27, 2008, 09:47
Default Re: out flow conditions
Posts: n/a
The method of imposing boundary conditions on the characteristics usually works well even for supersonic flow. You might want doulbe check. It is true that if the flow is supersonic and the supersonic velocity is going "out" through the boundary then all your characteristics are actually out-going, and none is incoming. Usually one would set the incoming characteristics to zero to avoid any in-coming (relfected) wave. Make sure that you check the veolcity of the flow at that boundary to make sure it is supersonic everywhere and all the time, as if it is subsonic, then there will be an incoming characteristics that you will have to set to zero. In theory imposing the BC on the characteristics is enough to avoid the reflection of waves through a boundary, but it is better to set the in-coming characteristics to zero.
  Reply With Quote


Thread Tools
Display Modes

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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Wind turbine simulation Saturn CFX 48 October 25, 2017 06:07
Pulsatile Flow Boundary Conditions Lior FLUENT 3 April 20, 2014 07:26
Compressible Flow over Airfoil. Boundary Conditions jose21 OpenFOAM 2 November 3, 2013 07:58
mass flow in is not equal to mass flow out saii CFX 2 September 18, 2009 08:07
Jump conditions - incompressible fluid flow momentum_waves Main CFD Forum 1 August 18, 2007 09:50

All times are GMT -4. The time now is 00:14.