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

Pressure correction BC using SIMPLE

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

LinkBack Thread Tools Display Modes
Old   July 11, 2007, 08:19
Default Pressure correction BC using SIMPLE
André Gaathaug
Posts: n/a
Hi I just started a course in CFD at my masters education. I am working on my own CFD solver, but I found a bit of a problem defining the BC of the pressure-correction when using the SIMPLE algorithm. It's especially wall-BC for the pressure-correction I find hard, but also outlet-BC for pressure-correction. I find pressure-correction BC hard to figure out since they give no physical meaning to me at all. Please reply if you have a hint to the BC or know where I can find a hint.

For visualization of velocities I just wonder about wether to use mean values for the x- and y-velocity, since I am using the backwards staggered grid and then no velocity is stored on the same place. Do I mean the values and place them in the centers as all the scalars?
  Reply With Quote

Old   July 11, 2007, 16:07
Default Re: Pressure correction BC using SIMPLE
Posts: n/a

Incompressible SIMPLE:

-Inlet, Wall: massflux through boundary is given: massflux correction is zero, so pressure correction gradient is zero there and you have a Neumann Boundary-Condition -Outlet: Usually velocity is extrapolated and will be corrected to satisfy continuity. These corrected velocities are then considered to be fixed for the current iteration and so the massflux there is considered to be given.

So you have Neumann Boundary conditions on all boundaries, the pc becomes singular and you have to fixe the pressure at one point to get a solution.

For the compressible extension of SIMPLE all becomes a bit more complicated, look in the book by Ferziger and Peric!

Good Luck...
  Reply With Quote

Old   August 3, 2007, 01:38
Default Re: Pressure correction BC using SIMPLE
Posts: n/a
dear Andre,

First make sure that u-velocity and v-velocity points coincide with physical vertical and horizontal boundaries respectively. Accordingly, other boundary nodes lie outside the physical boundaries. This is the place where beginners struggle. For excellent explanation of implementation of boundary conditions, i suggest you to refer CFD book by Malalasekara & Versteeg. hope it helps..

  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
Divergence detected in AMG solver: pressure correction emlejeen FLUENT 5 December 15, 2016 00:47
Pressure BC for combustion chamber Giuki FLUENT 1 July 19, 2011 11:35
Simple question about pressure variation Rooz Main CFD Forum 3 February 6, 2004 17:24
pressure driven flow by pressure correction method justentered Main CFD Forum 0 December 30, 2003 00:52
Gas pressure question Dan Moskal Main CFD Forum 0 October 24, 2002 22:02

All times are GMT -4. The time now is 19:21.