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

cyclone problem

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 23, 2002, 17:21
Default cyclone problem
  #1
Jichun
Guest
 
Posts: n/a
Hello, everyone,

Currently, I am using FLUENT to solve a cyclone problem. I know this is a typical problem that FLUENT can handle using ASM model. My question is that for a cyclone, there are two outlets with pressure_outlet boundary condition. When I turn on the multiphase model, I need to set the volumn fractions for the particulate phase at the outlets. The problem is how can I know the volumn fractions for the particulate phase ahead of time? These values should be obtained by solving this problem. Is there anyone could kindly give me some suggestions on this problem? Thanks a lot.
  Reply With Quote

Old   April 26, 2002, 20:58
Default Re: cyclone problem
  #2
Jin-Wook LEE
Guest
 
Posts: n/a
Of course, the values are obtained by solving your problem if you finish the calculation. You don't need to input them. Instead, initial guess with arbitrary value is enough.

The exact input(volume fraction) is required if there is backflow. In this case(backflow), CFD(or Fluent) require the input because it is actually 'INLET' because of the backflow.

Sincerely, Jinwook
  Reply With Quote

Old   April 29, 2002, 18:08
Default Re: cyclone problem
  #3
Jichun
Guest
 
Posts: n/a
I really appreciate your response to my post. Just as you said, if there is a backflow occuring in reality I have to treat it's boundary conditions as pressure_inlet type. The thing is: how can I know the volume fraction ahead of time? Can I set whatever values at that boundary or will these values be updated during the calculation? Again, thanks a lot!

Have a nice day!

JiChun
  Reply With Quote

Old   April 29, 2002, 20:43
Default Re: cyclone problem
  #4
Jin-Wook LEE
Guest
 
Posts: n/a
Physically, it is OUTLET. The best way is to make the computational outlet as 'real outlet'. Then you don't need to input them. Instead, Fluent calculate the value even though you give any value, which is only initial guess.

Otherwise(if there is backflow through the part domain of outlet or full domain of outlet), the computational iutlet is physically partly inlet or fully inlet. Then, unfortunately, there is no way to predict the value. It is nature and it is CFD. As we can simply guess, we should input the all values for inlet, the same situation for the backflow outlet which is physically inlet(partly or fully).

So, if you don't have the boundary condition for the value of outlet where is backflow, you should make the outlet as 'real outlet'. The simple approach to make the outlet as 'real outlet' is to extend the computational domain to the far downstream in order to prevent backflow.

If you live in Korea, you can touch me by, 016-723-8750.

Sincerely, Jinwook

  Reply With Quote

Old   May 16, 2002, 04:43
Default Re: cyclone problem
  #5
cwflying
Guest
 
Posts: n/a
Could you tell me which boundary conditions you applied to the aircore?
  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
conduction problem venkataramana OpenFOAM 3 December 1, 2013 08:30
area does not match neighbour by ... % -- possible face ordering problem St.Pacholak OpenFOAM 9 November 22, 2011 11:02
Adiabatic and Rotating wall (Convection problem) ParodDav CFX 5 April 29, 2007 19:13
Cyclone separator RSM mesh problem kharnab FLUENT 1 April 16, 2007 09:24
Is this problem well posed? Thomas P. Abraham Main CFD Forum 5 September 8, 1999 14:52


All times are GMT -4. The time now is 10:22.