|December 28, 2013, 03:27||
Vortex or Circulation Region at the outlet or opening
Join Date: Dec 2013
Posts: 2Rep Power: 0
I'm trying to understand one thing but I haven't understood it yet. So my problem is let's say we have a jet and I'm doing a transient analysis. I place the outlet at least 10 times far than the diameter of the jet. Or transient analysis of flow over a cylinder. When the created vortices by the jet or cylinder reach outlet not all the flow is going out. In that case should I use opening all the time? And also we do not know the inward flow direction angle - should I use entrainment option under opening BC?
I'm confused. I appreciate any help.
Thank you very much.
|December 28, 2013, 05:44||
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 11,282Rep Power: 88
There are many options. You could use an outlet and have walls created at the back flow sections. Or you could have several varieties of opening as you suggest.
They all will work. But the difference is that some of them will require the downstream boudary to be further away then others before you get acceptable accuracy. And a second major factor is they have different numerical stabilities (the simpler outlets are more stable than the more complex openings).
So the only universal answer is - do a sensitivity study and deteremine how far down stream the boundary condition you have chosen needs to be to get the accuracy you require. If you are lookign for the best option repeat this for a number of boundary types and you will find the best one for your case.
|Thread||Thread Starter||Forum||Replies||Last Post|
|Using Opening B.C. for both inlet and outlet||SH_P||CFX||1||June 11, 2012 20:15|
|opening sims as a wall.||Curran919||CFX||8||March 19, 2012 22:31|
|Outlet BC for disturbed Poiseuille flow||murx||CFX||10||February 22, 2012 14:55|
|Trimmed cell and embedded refinement mesh conversion issues||michele||OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ...||2||July 15, 2005 04:15|
|Import gmsh msh to Foam||adorean||Open Source Meshers: Gmsh, Netgen, CGNS, ...||24||April 27, 2005 08:19|