CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLOW-3D

Can we use Dynamic Mesh in VoF

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

Reply
 
LinkBack Thread Tools Display Modes
Old   December 8, 2009, 13:07
Default Can we use Dynamic Mesh in VoF
  #1
New Member
 
Join Date: Dec 2009
Posts: 4
Rep Power: 7
Tygrys is on a distinguished road
Hi everyone,
I try to solve problem with droplet break-up.
To solve this case I used volume of fluid methods. When I was using 3D case I had problem with to big grid. I would like to ask if it possible to concentrate grid point near the droplet. It is possible to use dynamic mesh or reference frame to VoF method? Or maybe could You recommend another method?

Thank you for any advices.
Best regards
Lukasz
Tygrys is offline   Reply With Quote

Old   December 12, 2009, 08:59
Default Re
  #2
New Member
 
Jemyung Cha
Join Date: Sep 2009
Posts: 8
Rep Power: 7
jemyungcha is on a distinguished road
Lukasz

sorry I don't fully understand what you point is.

:-)


it needs a number of grid for droplet breakup analysis using VOF.

(flow module + VOF = unsteady problem. and grid quality and the number affect solution)


You told about "concentration near the droplet".......right?

But think about it. Behavior of droplet not static but dynamic.

Using the dynamics mesh hardly be applied to this kind of problem.

"Dynamic" means that mesh should moves with droplet's motion. I am not sure whether it affect the solution of this problem.

If i were you, i would not use this function.


The only solution for good analysis result is (My own thought)

high performance computer and parallel processing.


I am using another commercial CFD code (CFD-ACE+) and quad core (intel i5) pc.

but i am not satisfied its performance. too time consuming work.

about 80,000 cells brought me 3~4 days per single analysis (3D analysis of droplet breakup in the microchannel).

I want to hear other researcher's experience about CFD.

Jemyung
jemyungcha is offline   Reply With Quote

Old   December 14, 2009, 11:36
Default
  #3
New Member
 
Join Date: Dec 2009
Posts: 4
Rep Power: 7
Tygrys is on a distinguished road
Sorry for my pure English language.
You had correctly understood my problem. Recently I use parallel processing (4 CPU), but my case have almost 800 000 cells. So I need 2-3 weeks to solve it. That is why I try to find less consumption time method.
Lukasz
Tygrys is offline   Reply With Quote

Old   December 16, 2009, 05:34
Default
  #4
Senior Member
 
Join Date: Mar 2009
Posts: 129
Rep Power: 8
ck5285 is on a distinguished road
All
I did some benchmark before for Fluent & CFX and Flow-3D in droplet simulation. Flow-3D is much faster in simulation time due to its True-VOF approach vs typical VOF approach that solve both air and fluid in momentum equation. Hope this help.
ck5285 is offline   Reply With Quote

Old   December 18, 2009, 20:12
Default
  #5
Senior Member
 
michael barkhudarov
Join Date: Mar 2009
Posts: 331
Rep Power: 9
MuxaB is on a distinguished road
Quote:
Originally Posted by Tygrys View Post
Sorry for my pure English language.
You had correctly understood my problem. Recently I use parallel processing (4 CPU), but my case have almost 800 000 cells. So I need 2-3 weeks to solve it. That is why I try to find less consumption time method.
Lukasz
Lukasz,

Why is it so long? What is the time step size and the total simulation time?

Michael
MuxaB is offline   Reply With Quote

Old   December 20, 2009, 19:14
Default
  #6
New Member
 
Join Date: Dec 2009
Posts: 4
Rep Power: 7
Tygrys is on a distinguished road
The time step size is 10^-8. Flow time which is needed to droplet break-up it's about 0.002 [s] (for We=20 and grid size about 10^6 cells). Real time to solve this problem is about 3-4 weeks.

Regards
Lukasz
Tygrys is offline   Reply With Quote

Old   December 21, 2009, 20:49
Default
  #7
Senior Member
 
michael barkhudarov
Join Date: Mar 2009
Posts: 331
Rep Power: 9
MuxaB is on a distinguished road
Quote:
Originally Posted by Tygrys View Post
The time step size is 10^-8. Flow time which is needed to droplet break-up it's about 0.002 [s] (for We=20 and grid size about 10^6 cells). Real time to solve this problem is about 3-4 weeks.

Regards
Lukasz
Is the time step size kept down by the surface tension or viscous stability limits? Can you try using implicit approximations for those forces to relax the stability limits on the time step size?
MuxaB is offline   Reply With Quote

Old   December 23, 2009, 14:17
Default
  #8
New Member
 
Join Date: Dec 2009
Posts: 4
Rep Power: 7
Tygrys is on a distinguished road
I using small time step to capture the oscillation of the droplet interface and the associated high velocity(recommended by Fluent Tutorial Guide). I using implicit approximation for this calculation.
Tygrys is offline   Reply With Quote

Old   December 23, 2009, 17:22
Default
  #9
Senior Member
 
michael barkhudarov
Join Date: Mar 2009
Posts: 331
Rep Power: 9
MuxaB is on a distinguished road
Quote:
Originally Posted by Tygrys View Post
I using small time step to capture the oscillation of the droplet interface and the associated high velocity(recommended by Fluent Tutorial Guide). I using implicit approximation for this calculation.
I am not sure Fluent's advice applies to FLOW-3D simulations, does it?
MuxaB is offline   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
Dynamic mesh update problem. David FLUENT 3 March 15, 2012 06:02
How to Us Dynamic Mesh in OpenFOAM lzgwhy OpenFOAM Programming & Development 4 November 6, 2009 06:18
Dynamic Mesh Pj FLUENT 1 March 12, 2007 16:16
dynamic mesh and sliding mesh nasser FLUENT 0 November 1, 2005 03:37
Help: Is it possible to use dynamic mesh model and Valery Ponyavin FLUENT 1 September 20, 2003 14:18


All times are GMT -4. The time now is 09:06.