# Multiphase Problem Settings

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 LinkBack Thread Tools Display Modes
 June 2, 2012, 02:08 Multiphase Problem Settings #1 New Member   Anniruddha Join Date: May 2012 Posts: 4 Rep Power: 5 I am student doing my project on FLUENT, piston analysis for oil cool gallery application. I am using VOF model. In that my solution is diverging. Can anyone help me out with the appropriate settings? My objective is to find out the heat transfer and temperature distribution in the cooling oil gallery. I have tried with SIMPLE and PISO but still the solution is diverging.

 June 5, 2012, 03:55 #2 New Member   Elias Paez Join Date: Nov 2011 Location: Madrid Posts: 25 Rep Power: 5 Hi, Is your simulations steady or transient? wich method are you using for VOF (implicit or explicit). If you are in transient and explicit, you should decrease the time step (check the courant number), Piso is a good option, but I do not think it is your problem.

 June 11, 2012, 03:13 #3 New Member   Anniruddha Join Date: May 2012 Posts: 4 Rep Power: 5 Thank you sir for yor reply. Avtually i am using Transient, VOF (implicit) settings. Still the solution is getting diverged in the "epsilon". Please help me for the correct settings.

June 12, 2012, 14:09
#4
New Member

Join Date: Nov 2011
Posts: 27
Rep Power: 5
Quote:
 Originally Posted by aniruddha.nasalapurkar Thank you sir for yor reply. Avtually i am using Transient, VOF (implicit) settings. Still the solution is getting diverged in the "epsilon". Please help me for the correct settings.
I believe that for transient calculations, the VOF explicit option would be more consistent. Also you should use the "Geo-reconstruct" discretization for the volume fraction. I believe that the "first-order" is the default for the implicit method and this is not good since the interface between the phases is not well defined through this discretization.

I have seen in some works the application of PISO method with "0" value set in the "Skewness correction" option also.

You should also check if your mesh meets the requirements of turbulence model and wall functions in use.

Good luck.

 June 13, 2012, 13:11 #5 New Member   Elias Paez Join Date: Nov 2011 Location: Madrid Posts: 25 Rep Power: 5 Looks like your problem is more with turbulence model (epsilon divergence) than the VOF, so maybe you should check this part. As Jabba wrote, the best option of VOF is the explicit with geo-recronstuc, specially when you have to simulate an interface (free-surface), but also can be very unstable and you have to be care of the courant number or use the NITA option. Another option of VOF (no so good as explict-geo) is use the VOF implicit with "modified HRIC" that has a little diffusion in the interface but is more stable

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post suiger CFX 0 December 11, 2010 05:16 100tinela CFX 2 November 18, 2010 20:32 Amir Khodabandeh FLUENT 1 March 13, 2009 09:43 Derek Jing FLUENT 0 May 12, 2002 11:52 Brett Towler CFX 2 August 18, 2000 16:38

All times are GMT -4. The time now is 06:58.

 Contact Us - CFD Online - Top