CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

reverse flow

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 24, 2005, 01:54
Default reverse flow
  #1
kiao
Guest
 
Posts: n/a
I am a total newbie so please understand... Trying to simulate sprays. So I set up a simple box 1mx0.6m 2D domain as sprays don't travel that far with a surface opening at the top at 0.1m. Inlet velocity =1m/s entering at the surface opening. I set turbulence model k=1.0, e=0.5 This works fine, and then I try vel = 20m/s and get reverse flow. Do I have to extend the domain or change to unsteady flow to simulate the spray.
  Reply With Quote

Old   May 24, 2005, 03:47
Default Re: reverse flow
  #2
kawthar
Guest
 
Posts: n/a
I think before to make unsteady flow, try to extend the domain in the downstream and for precison change the options of k-e model. You use now k=1 (Default value by fluent) so try to use (I and Dh ). For I use an estimate value from the expression in doc of fluent ( Imax=10%) and Dh = 2* Length in you case 2m. And let us know if it will be OK
  Reply With Quote

Old   May 24, 2005, 22:44
Default Re: reverse flow
  #3
kiao
Guest
 
Posts: n/a
extended the domain Dh (Hydraulic Diameter?) = 2. That actually made it worse than the original k-e settings.

It converges at k=1, e=0.05. Whenever I reduce the opening i get reverse flow. Is it because the flow is entering an open flow field causing reverse flow which rebounds off the adjacent wall (wall parallel to the opening)

geometery

--------ooo--------

I I

I I

I I

I I

I I

I I

-------------------
  Reply With Quote

Old   May 26, 2005, 14:06
Default Re: reverse flow
  #4
us
Guest
 
Posts: n/a
I hope you know to set different Dh depending on the hydraulic dia of pipe inlet/outlet. for example, in your case, spray hole dia is, 0.1m or so. Means, you can't define Dh=2 there. -US
  Reply With Quote

Old   May 26, 2005, 14:08
Default Re: reverse flow
  #5
us
Guest
 
Posts: n/a
Also, I is aproaximately 4% for Re=50000. So, adjust that value accordingly.
  Reply With Quote

Reply

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
Reverse Flow Bharati FLUENT 0 September 14, 2010 01:09
Flow simulation in reverse drum mixer Patel Chirag CFX 0 July 19, 2010 15:05
reverse flow alikami FLUENT 1 June 2, 2010 04:19
Reverse flow in the VOF model yan FLUENT 1 May 26, 2005 09:14
reverse flow Giovanni FLUENT 11 October 15, 2001 03:01


All times are GMT -4. The time now is 17:00.