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

CFD for Internal Flows

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 28, 2002, 10:57
Default CFD for Internal Flows
  #1
Chan K I
Guest
 
Posts: n/a
Hi,

I've been running Jameson's Runge-Kutta time-marching scheme for a compressible internal flow simulation.

When plotting mass flow vs time at a certain location along the duct, I notice that the plot is sinusoidal type with decaying amplitude...but it decays very slowly and convergence could thus take a long time.

Appreciate advice on how this long settling time could be reduced.

Thanks in advance!
  Reply With Quote

Old   August 29, 2002, 00:38
Default Re: CFD for Internal Flows
  #2
versi
Guest
 
Posts: n/a
Your problem is how to accelerate convergence. Jamenson (JST) dissipation model is usually used together with multigrid, enthapy damping, local time stepping, and applies to transonic flow. Check if you have used these techniques.
  Reply With Quote

Old   September 3, 2002, 10:40
Default Re: CFD for Internal Flows
  #3
Pao
Guest
 
Posts: n/a
I am also running Jame's Runge Kutta time marching. But for external flow, and I would like to do internal flow too. What is your boundary condition at the inlet and exit? Do you use Riemann invariant? Thanks for your info.
  Reply With Quote

Old   September 4, 2002, 19:00
Default Re: CFD for Internal Flows
  #4
Chan K I
Guest
 
Posts: n/a
Hi,

Inlet: Total Pressure and Temperature,Flow Angle Exit: Static Pressure.

Yes, Riemann invariant used.

Regards
  Reply With Quote

Old   September 6, 2002, 10:39
Default Re: CFD for Internal Flows
  #5
Pao
Guest
 
Posts: n/a
Thanks for your info. In Jameson's code, he solve density, den*u, den*v, den*w, den*E. So the boundary condition at inlet and exit need to specify the above 5 parameters, den,den*u,den*v,den*w,den*e. So at inlet, you use total pressure, temp and flow angle to calculate the above 5 parameters. But at the exit, only pressure.Do you use pressure to compute the above 5 parameters? Or extrapolate from the inside domain? If you use Riemann to extrapolate, pressure might not be the same as you specify. I know in physics we specify pressure at exit. But from computer coding, exit need to specify the above 5 parameters. Thank you again for your advice.
  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
CFD Salary CFD Main CFD Forum 17 January 3, 2017 18:09
2d CFD solver for convection dominated flows Tiziano Main CFD Forum 1 October 10, 2006 07:00
CFD Shear flows Alok Chandra Main CFD Forum 5 October 20, 2003 11:36
Can we quantify the fruits of CFD? Brady Brown Main CFD Forum 14 December 15, 1999 10:42
ASME CFD Symposium - Call for Papers Chris R. Kleijn Main CFD Forum 0 September 8, 1998 09:19


All times are GMT -4. The time now is 00:49.