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

pressure coefficient problem (FLUENT)

Register Blogs Community New Posts Updated Threads Search

Like Tree1Likes
  • 1 Post By J. Kim

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 19, 2006, 06:23
Default pressure coefficient problem (FLUENT)
  #1
pimpin
Guest
 
Posts: n/a
Dear all, i have a 2d arfoil profile which i am testing on FLUENT, i use a speed of M=0.8 or around. I have a problem with the validity of my results as my Pressure coefficient plot shows Cp of -1.10e5 and above (...it would appears that i have no stagnation point where Cp=1 ! Any ideas please reply. If you also need more precision on my case let me know i ll reply. thanks

pimpin

  Reply With Quote

Old   January 19, 2006, 06:29
Default Re: pressure coefficient problem (FLUENT)
  #2
Luca
Guest
 
Posts: n/a
Take a look to the reference values panel. Luca
  Reply With Quote

Old   January 19, 2006, 07:18
Default Re: pressure coefficient problem (FLUENT)
  #3
pimpin
Guest
 
Posts: n/a
THanks Luca for the reply , but could let me know what i will be looking in the reference panel to go wrong!

I normally look at the reference panels and the data in it and it looks ok to me (Pressure, velocity,temp, ...). COuld you let me know what could be a wrong value or where i could have gone wrong?

Pimpin
  Reply With Quote

Old   January 19, 2006, 14:34
Default Re: pressure coefficient problem (FLUENT)
  #4
J. Kim
Guest
 
Posts: n/a
Report-Reference Values-.....

And you need to change reference values to get a non-dimensional data that need normalized values. For example, fluid density, reference (or inlet) velocity, length scale (i.e. chord length or width, height of the bluff body) are necessary to calculate Cp values.

Please be careful that your Cp at the stagnation point will be different to 1 when you used inlet velocity as a reference velocity.
FluidAerodynamics likes this.
  Reply With Quote

Old   February 11, 2011, 11:19
Default
  #5
New Member
 
alidogrul
Join Date: Feb 2010
Location: Turkiye
Posts: 13
Rep Power: 16
alidogrul is on a distinguished road
What velocity should I give as reference velocity instead of my inlet velocity?

I get the same result with "pimpin" Cp=0 at the stagnation point where it should instead be equal to 1.
alidogrul is offline   Reply With Quote

Old   May 29, 2012, 03:11
Default
  #6
Member
 
mahzad_kh
Join Date: Jun 2010
Posts: 38
Rep Power: 16
mahzad is on a distinguished road
Dear mr.kim
with regard to what you mentioned above, how must we calculate cp? I mean what velocity must be used to calculate Cp? we can't use any other velocities for calculating Cp!!!
mahzad is offline   Reply With Quote

Old   May 29, 2012, 03:49
Default
  #7
Member
 
mahzad_kh
Join Date: Jun 2010
Posts: 38
Rep Power: 16
mahzad is on a distinguished road
I've done renumbering before.
mahzad is offline   Reply With Quote

Old   June 2, 2012, 19:06
Default
  #8
Member
 
Khayyamian
Join Date: Dec 2010
Posts: 46
Rep Power: 15
hadikhayyamian is on a distinguished road
Based on this see end of passage,:

https://confluence.cornell.edu/displ...+%28Physics%29

I guess you should set inlet velocity as your reference. this is useful to monitor drag coefficient convergence by going to solve---monitor---force and select drag.

Also it is worthy if you check finally your drag coefficient by going to report--force---... and compare with results graphed in the monitor window. I wonder if they are the same or not. if you found that, please let me know.
hadikhayyamian is offline   Reply With Quote

Old   March 24, 2014, 23:37
Default calculation of Cp
  #9
New Member
 
Aalisha
Join Date: Jan 2014
Posts: 18
Rep Power: 12
aalisha is on a distinguished road
Hello everyone,

I am working on a three blade turbine. I have monitored the drag, lift and moment forces (cl,cd and cm). Can anyone help me how to calculate the Cp (power coefficient) using these values. It will be a great help.

Thanks
aalisha is offline   Reply With Quote

Reply


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
Pressure coefficient Giuseppe FLUENT 2 July 26, 2015 04:19
pressure inlet bc in fluent nikhil FLUENT 0 June 28, 2010 17:30
Operating Pressure (Natural Convection problem) Andrew Tress Main CFD Forum 1 July 3, 2006 17:00
what the result is negatif pressure at inlet chong chee nan FLUENT 0 December 29, 2001 06:13
Hydrostatic pressure in 2-phase flow modeling (long) DS & HB Main CFD Forum 0 January 8, 2000 16:00


All times are GMT -4. The time now is 06:45.