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

Total pressure drop

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 26, 2003, 14:40
Default Total pressure drop
  #1
Swapnil
Guest
 
Posts: n/a
Hi all,

I am working on a system comprised of two triangular ducts intersecting each other at 90 degrees. There are two inlets and two outlets. At the intersection the flow gets diverted and a fraction of the flow coming from one inlet (say inlet 1) goes straight (outlet 1) and another fraction bends at 90 degrees and goes to outlet 2 . Same thing happens to flow from inlet 2.

How to calculate the total pressure drop for this system.

Regards, Swapnil.
  Reply With Quote

Old   January 26, 2003, 19:56
Default Re: Total pressure drop
  #2
Jan Rusås
Guest
 
Posts: n/a
I guess that the difference of a volume average of the total pressure at the outlet and inlet could give the answer. (mass average will do if the flow is incompressible)

  Reply With Quote

Old   January 27, 2003, 11:21
Default Re: Total pressure drop
  #3
fly
Guest
 
Posts: n/a
Hi, Jan:

Did you compare the simulation results with real case? I compared the pressure drop. It seems the CFX results are smaller than that of regular method. fly
  Reply With Quote

Old   January 27, 2003, 12:16
Default Re: Total pressure drop
  #4
Hannah liang
Guest
 
Posts: n/a
Hi, Fly:

I found the same result with you. And If I refine the mesh, the result even become smaller. Could you find the explaination from theory in books?

Hannah
  Reply With Quote

Old   January 27, 2003, 15:22
Default Re: Total pressure drop
  #5
Swapnil
Guest
 
Posts: n/a
Hi fly and Hannah liang ,

are you people working on triangular ducts?
  Reply With Quote

Old   January 27, 2003, 17:33
Default Re: Total pressure drop
  #6
Jan Rusås
Guest
 
Posts: n/a
I would be surprised if the values was exactly the same. There are some uncertainities in both measurements and numerical results. I know it is very difficult to get exact numbers when looking for the pressure drop. I have had some succes with predicting pressure drop when using higher order differencing, double precision and doing a grid independency investigation and calculating an estimate of the pressure drop from a Richardson extrapolation of the pressure drop obtained with the three grids. Regards Jan
  Reply With Quote

Old   January 28, 2003, 10:38
Default Re: Total pressure drop
  #7
sxf
Guest
 
Posts: n/a
Hi, Jan:

I agree with your on the pressure drop for measurements and numerical results. But I think they should be the same on some extend. Could you share your success results with me.

Thanks

SXF
  Reply With Quote

Old   January 28, 2003, 14:27
Default Re: Total pressure drop
  #8
Jan Rusås
Guest
 
Posts: n/a
Dear sxf, You state that "they should be the same on some extend". I do agree with you, what could I else ). But when will you say you are satisfied, 5% or 10% or 20% etc. What kind of accuracy should be expected from a numerical code with many assumptions and with many constants based on old experiments with an accuracy on???. I remember once a paper with different test cases where several numerical codes was investigated, but I do not remember the exact values , but one should not be surprised if there are some deviations. Regards Jan
  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
buoyancy - losses estimation through total pressure clrsgfn CFX 4 November 10, 2010 12:05
Pressure drop? Munni FLUENT 4 March 25, 2010 15:21
total pressure in CFX Atit Koonsrisuk CFX 0 January 1, 2005 06:46
Total pressure to static pressure ratio roadracer Siemens 1 April 17, 2003 06:31
what the result is negatif pressure at inlet chong chee nan FLUENT 0 December 29, 2001 06:13


All times are GMT -4. The time now is 14:22.