CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > CFX

Pressure loss in pipe

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

LinkBack Thread Tools Display Modes
Old   January 5, 2007, 06:22
Default Pressure loss in pipe
Posts: n/a
Hi guys and girls;-)

I'm going an investigation of fully developed laminar air flow in a horizontal pipe (using periodic boundaries and creating a subdomain and defining a general momentum source in the z-direction) in ANSYS CFX 10.0.

I'm trying to determine the pressure loss through the pipe using the table viewer in CFX-Post but the results don't match the ones I have calculated theoretically.

Here is what I have inserted in the table viewer:

areaAve(ptot )@Domain Interface 1 Side 1 - areaAve(ptot )@Domain Interface 1 Side 2

Any idea as to why the pressure from the table viewer doesn't comply to the theoretically calculated?

Ps. I have checked that I get a laminar velocity profile " although I find that I need a Reynolds number at about 25-70 in order the match the theoretical profile. If I use larger Reynolds numbers i.e. 1000 I get a much more turbulent looking profile which surprises me as normally laminar flow presides in pipe flow until RE = 2300.

Any ideas or comments about something I could be doing wrong are welcome...

Regards Chris

  Reply With Quote

Old   January 5, 2007, 12:04
Default Re: Pressure loss in pipe
Posts: n/a
Hi Chris,

You need to add in the effect of the momentum source you used to drive the flow, it will not be included in the pressure. Actually, since you are prescribing the pressure drop, you should compare the mass flow and velocity profile to the theoretical values for the pressure drop you have prescribed.

If you still don't acheive the same results, run again with progressively finer meshes. Eventually the numerical dissipation due to the mesh resolution should be reduced to the order of the roundoff error.

Regards, Robin
  Reply With Quote


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
total pressure change in a pipe flow Im FLUENT 5 February 23, 2017 09:55
"Pressure Inlet" Boundary Setup Wijaya FLUENT 15 May 18, 2016 10:08
Pressure Drop - Please Help - Simple Pipe Flow Joe A. FLUENT 2 April 23, 2007 07:50
Does star cd takes reference pressure? monica Siemens 1 April 19, 2007 11:26
Gas pressure question Dan Moskal Main CFD Forum 0 October 24, 2002 22:02

All times are GMT -4. The time now is 18:31.