CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

Free Surface Convection Model

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 23, 2015, 16:14
Default Free Surface Convection Model
  #1
Member
 
robo
Join Date: May 2013
Posts: 47
Rep Power: 13
robo is on a distinguished road
Hey, can anyone tell me what CFX is actually doing when it solves free surface flows? I know that it's using a VoF approach, but the theory manual only says that it uses "some special discretization options to keep the interface sharp" including "A compressive differencing scheme". Is it using cicsam or something like that? I need to know what actual discretizations are being done on the convective term in the VoF equations. The theory manual seems to be pretty much useless at actually describing the theory...
robo is offline   Reply With Quote

Old   September 26, 2015, 21:43
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,862
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
No it is not using CICSAM. Also, do not expect to have the entire theory behind it explained. It is commercial software and they choose to keep some details confidential.

I think the CFX training courses have some more detail about the implementation. Maybe ask your CFX support person about it.
ghorrocks is offline   Reply With Quote

Old   September 29, 2015, 15:18
Default
  #3
Member
 
robo
Join Date: May 2013
Posts: 47
Rep Power: 13
robo is on a distinguished road
If you know it's not CICSAM, does that mean you know what it is?

I appreciate your taking the time to respond, but I find your answer pretty frustrating. I'm not asking for the implementation algorithm or some sort of special secret sauce. If a company is going to keep their discretization techniques confidential, then I don't see how they can expect people to be able to do academic work with their product. It's not like this is some bizarre standard to expect either; this info is available from competing codes such as Fluent, including the citation of the academic papers.

I will see if I can get the answer from our support person. Thanks again.
robo is offline   Reply With Quote

Old   September 29, 2015, 19:39
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,862
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Sorry about the frustrating answer. I did look into this area many years ago but it has been so long I cannot recall the exact details so I am sorry if my answer is a bit vague. The default compressive scheme is not like the surface sharpening algorithms in Fluent (CICSAM, Geo Reconstruct) - but I recall it is similar to HRIC. But it has been so long I cannot be more specific.

Also, I have just had a quick look in the documentation and cannot find anything about the compressive scheme (other than it is used for volume fraction advection)

There is the interface compression level setting - but there is no documentation about exactly what it does.

Yes, your best bet is ANSYS support.
ghorrocks is offline   Reply With Quote

Old   September 30, 2015, 09:01
Default
  #5
Member
 
robo
Join Date: May 2013
Posts: 47
Rep Power: 13
robo is on a distinguished road
No worries about the answers, not your fault that the theory documents aren't a bit better. Thanks again for all your help.
robo is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Free surface is not falling (VOF MODEL, TANK DRAINAGE) Blue FLUENT 3 November 28, 2013 06:51
free surface model sjtusyc CFX 3 September 5, 2012 19:33
Can Flow-3D plot the free surface area in Iso-surface or colour variable? therockyy FLOW-3D 1 June 20, 2010 20:36
About free surface model? Cheng, Y.C. Siemens 0 September 9, 2002 10:11
CFX4.3 -build analysis form Chie Min CFX 5 July 13, 2001 00:19


All times are GMT -4. The time now is 03:30.