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

question about unsteady run and swirl number

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 9, 2011, 03:49
Default question about unsteady run and swirl number
  #1
Member
 
Ahmet
Join Date: Mar 2011
Location: Ankara/ Turkey
Posts: 37
Rep Power: 6
a_cucen is on a distinguished road
i have a case about unsteady flow. mesh has approximately 750.000 cells. but i don' t know what the time step must be? how can i calculate the time step? What is the relation between time step and cells. and second question: how can i calculate swirl number; i found that SN= G_theta/R.G_x. but i could not find how to calculate G_theta and G_x.

best regards,
Ahmet.
a_cucen is offline   Reply With Quote

Old   March 14, 2011, 04:00
Default
  #2
Senior Member
 
Join Date: Jun 2009
Posts: 100
Rep Power: 8
alastormoody11 is on a distinguished road
A general rule of thumb is to use a time step which is 1/100 th of the approximate time required for the flow to traverse the entirety of the CV.

If you see that the solution is taking a large number of iterations to converge you might consider using half of the initial time step and so on.
alastormoody11 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



All times are GMT -4. The time now is 01:48.