CFD Online Logo CFD Online URL
Home > Forums > FLUENT

discretization scheme in recirculating flows

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

LinkBack Thread Tools Display Modes
Old   October 9, 2002, 08:48
Default discretization scheme in recirculating flows
Posts: n/a
Let me explain a little the context first. I'm trying to do some simulations of a coaxial jet running at low and high velocity ratios. It's well known since ages that such jet have a self-sustained oscillating recirculation zone at potential core ending at high velocity ratios. Simulations were conducted with a RANS formulation and i was making some parametric tests on discretization schemes when a strange problem emerged. here are the parameters :

- Momentum equation is at 1st order discretizeation

- turbulence équations are at a) first order then at b) second order.

When no recirculation is involved, switching to case b) has no influence on the mean fields nor on the turbulent ones. But when recirculation takes place in the jet, switching to b) greatly enlarge the turbulence level in the recirculation zone (a factor 5 from a) without having any effect on the mean fields. This amplification of turbulence appears independently of the model used (ke, RNG, RSM) but is more pronounced for isotropic formulations (i.e. ke).

If someone has an idea on how second order discretisation of turbulence eq. can influence turbulence level in recirculating zones without changing the mean levels, he (or she) can leave me a message.

Thx in advance for your help.
  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
Time discretization scheme HaKu Main CFD Forum 1 June 12, 2011 02:06
Discretization scheme for Convection Terms Mohammad Kazemi CFX 16 December 7, 2004 23:38
calculating recirculating turbulent flows with k-e Abhijeet Vaidya Main CFD Forum 10 November 18, 2002 09:21
MARS discretization scheme raymond Siemens 3 February 1, 2002 06:33
TVD scheme applied to axsymetric nozzle flows Zhou Hua Main CFD Forum 0 May 7, 1999 00:10

All times are GMT -4. The time now is 16:21.