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

Solving the turbulence equation

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 12, 2007, 09:24
Default Solving the turbulence equation
  #1
summer
Guest
 
Posts: n/a
Hello, everyone. Now I am trying to model two-phase flow using Eulerian multiphase model with dispersed k-e model. However, I have a convergent problem. When I tried to ingore the turbulence equation in the solution panel, I found it converges well. Does anyone know that whether my solution is reasonable without the turbulence equation? Or is it possible that I will get some reasonable solution when I add this turbulence equation later? Thank you very much.
  Reply With Quote

Old   July 12, 2007, 10:13
Default Re: Solving the turbulence equation
  #2
Joe
Guest
 
Posts: n/a
You need to give much more explicit on what you are modelling for anyone to be able to answer your question.
  Reply With Quote

Old   July 12, 2007, 11:20
Default Re: Solving the turbulence equation
  #3
summer
Guest
 
Posts: n/a
O.K. I am sorry that I stated my problem simply. Actually, I am trying to model air(gas)-water(liquid) two-phase flow problem using Eulerian multiphase model. It is unsteady solver with standard k-e turbulence model. I use vel-in for both phases and pressure-out boundary condiition. After the simulation runs, I noticed that the residual of the continuity is quite big (~ 0.1) and it stays flat. I tried to reduce the under-relaxation factor of momentum. The residual went down to ~ 0.001 but also stayed flat (did not converges!) Finally, I noticed that if I did not select the equations of turbulence under the panel of "solve->controls->solution", the residuals go down perfectly. I want to know the effect of the turbulence in the solving processing. Is it possible to get the reasonable solution in this way? BTW, I also tried to refine my mesh or reduce the time step during the calculation but the residuals did not go down. Thank you very much.
  Reply With Quote

Old   July 12, 2007, 16:30
Default Re: Solving the turbulence equation
  #4
Joe
Guest
 
Posts: n/a
Turbulence is multiphase flow is a thorny issue ... Reynolds number dependancy etc.
  Reply With Quote

Old   July 13, 2007, 09:57
Default Re: Solving the turbulence equation
  #5
Summer
Guest
 
Posts: n/a
I use air-water two-phase flow. Since the superfacial velocity for air is about 0.23 m/s and for liquid is 2 m/s and the void fraction is 10%. The Reynolds number for gas is only 736 but for liquid is 1e5, which is quite large.
  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
Calculation of the Governing Equations Mihail CFX 7 September 7, 2014 06:27
transsonic nozzle with rhoSimpleFoam Unseen OpenFOAM Running, Solving & CFD 7 April 16, 2014 03:38
SimpleFoam k and epsilon bounded nedved OpenFOAM Running, Solving & CFD 13 November 4, 2013 15:13
Problems with simulating TurbFOAM barath.ezhilan OpenFOAM 13 July 16, 2009 05:55
Could anybody help me see this error and give help liugx212 OpenFOAM Running, Solving & CFD 3 January 4, 2006 19:07


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