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

DNS using fluent

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 3, 2007, 13:50
Default DNS using fluent
  #1
adi
Guest
 
Posts: n/a
Can we use Fluent for direct numerical simulation?
  Reply With Quote

Old   July 3, 2007, 20:05
Default Re: DNS using fluent
  #2
Sham
Guest
 
Posts: n/a
i'd like to know too. i asked this question before but no one answered. hope someone is kind enough to shed some light here.
  Reply With Quote

Old   July 3, 2007, 20:35
Default Re: DNS using fluent
  #3
PTK
Guest
 
Posts: n/a
You simply use laminar flow - ie. directly compute the turbulence scales rather than modeling them(RANS). LES is a combo.

You need a very very dense mesh and I think the unsteady solver hence incredibly long times to do it properly.
  Reply With Quote

Old   July 4, 2007, 23:35
Default Re: DNS using fluent
  #4
kk
Guest
 
Posts: n/a
I can't understand why using laminar flow is using DNS method. Can laminar flow model account the turbulences in a non-laminar flow? I am also having a hard understand how laminar flow is solved in Fluent.
  Reply With Quote

Old   July 5, 2007, 11:01
Default Re: DNS using fluent
  #5
PTK
Guest
 
Posts: n/a
1)DNS isn't a method it simply means you don't use a turbulence model. You need incredibly dense grids though.

2)You need to look up a book for more info. As far as I know the laminar flow(which isn't a model) simply means viscous flow and so uses the Navier Stokes equations and the invscid flow doen't consider the viscosity and uses the Euler equations.

3)Laminar flow just solves the Navier Stokes equations without using a turbulence model. By using a very very fine grid you can directly compute the turbulence scales. RANS turbulence modeling just calculates a value for the turbulence that can be used by other function in Fluent.

I would advise you to read the fundamental(first few) chapters of any CFD book. Especially Computational Methods for Fluid Dynamics by Ferzier.

Please be aware I have no DNS experience so the above answers may need to be slightly modified.

PTK
  Reply With Quote

Old   July 9, 2007, 14:12
Default Re: DNS using fluent
  #6
Eugene
Guest
 
Posts: n/a
Almost DNS modelling will be under following conditions: At usage LES of model in 3d case, In unsteady setting, With very mesh sizes of a mesh of a rated net. Such that the minimum size of turbulent pulsings (Vortexes) was more mesh width. All spectrum of turbulent pulsings (Vortexes) here is considered.
  Reply With Quote

Old   July 9, 2007, 14:14
Default Re: DNS using fluent
  #7
Eugene
Guest
 
Posts: n/a
Almost DNS modelling will be under following conditions: At usage LES of model in 3d case, In unsteady setting, With very mesh sizes of a mesh of a rated net. Such that the minimum size of turbulent pulsings (Vortexes) was more mesh width. All spectrum of turbulent pulsings (Vortexes) here is considered.
  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
Abaqus - Fluent Coupling WITHOUT MPCCI s.mishra FLUENT 1 April 5, 2016 06:47
Two questions on Fluent UDF Steven Fluent UDF and Scheme Programming 4 September 20, 2013 16:30
DNS in FLUENT rajani FLUENT 7 May 28, 2013 04:25
What the differences flow equation of Fluent 6.3 and Fluent 12.1 opehterinar81 FLUENT 0 August 19, 2011 11:55
solving ocean wave with Fluent or CFX? gholamghar Main CFD Forum 1 March 21, 2009 13:49


All times are GMT -4. The time now is 04:02.