CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Post-Processing

Very high value of p_rgh than theoretical value

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 20, 2016, 05:26
Default Very high value of p_rgh than theoretical value
  #1
Member
 
Lee Jung Hoo
Join Date: Dec 2015
Posts: 37
Rep Power: 3
Jung hoo is on a distinguished road
hello, again me. I think that previous my question was too complicated and long. So here is summarized question!

As far as I know, p_rgh is (1/2)*rho*lUl^2. Is that right?

If so, the max value of p_rgh must be about 21125Pa at U(max) = 6.5m/s where rho is 1000kg/m^3.

But the mesured max value of p_rgh by paraview is about 300000Pa as below, and that is too high than theoretical value(about 21125Pa).

The number of mesuring points is three, and they are near the water surface(26m).



I'm wondering whether it is some kind of error or the theory for p_rgh that I know is wrong.



Additionally, the range of p_rgh is so weird measured at lower part of water surface as below.



Any idea can help me a lot!! Thanks!
Jung hoo is offline   Reply With Quote

Old   May 20, 2016, 05:42
Default
  #2
Senior Member
 
Pablo Higuera
Join Date: Jan 2011
Location: Singapore
Posts: 365
Rep Power: 10
Phicau is on a distinguished road
Hi Lee Jung Hoo,

p_rgh is not dynamic pressure. Check my thesis (page 111):

http://www.tesisenred.net/bitstream/...pdf?sequence=1

Best,

Pablo
Phicau is offline   Reply With Quote

Old   May 24, 2016, 00:04
Default
  #3
Member
 
Lee Jung Hoo
Join Date: Dec 2015
Posts: 37
Rep Power: 3
Jung hoo is on a distinguished road
Oh!! Thank you for your help! But the link http://www.tesisenred.net/bitstream/...pdf?sequence=1 is not available now..

Can you post another way to approach that link?? Thank you so much!!!!
Jung hoo is offline   Reply With Quote

Old   May 24, 2016, 01:06
Default
  #4
Senior Member
 
Pablo Higuera
Join Date: Jan 2011
Location: Singapore
Posts: 365
Rep Power: 10
Phicau is on a distinguished road
It is the middle of the night inSpain, the servers are probably under maintenance, try again later.
Phicau is offline   Reply With Quote

Old   May 24, 2016, 01:47
Default
  #5
Member
 
Lee Jung Hoo
Join Date: Dec 2015
Posts: 37
Rep Power: 3
Jung hoo is on a distinguished road
OK! I'll try it later. Thank you for your reply! ^_^
Jung hoo is offline   Reply With Quote

Old   May 25, 2016, 05:09
Default
  #6
Member
 
Lee Jung Hoo
Join Date: Dec 2015
Posts: 37
Rep Power: 3
Jung hoo is on a distinguished road
Hello Pablo, It's me again. I have read your paper that you recommended to me and now I can partially understand 'pseudo-dynamic pressure'.
I'm really appreciative of that!
Then.. could you please give me a way for measuring accurate values of p_rgh..?.
Does such utility exist? or Is that possible through paraview?
Thank you..!!
Jung hoo 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


Similar Threads
Thread Thread Starter Forum Replies Last Post
BC for Actuator Disk - Flow Vel from High Pressure to Low Pressure vinguva OpenFOAM Running, Solving & CFD 2 March 8, 2016 00:46
High Lift Airfoils At High Angles Of Attack Luiz Pancini FLUENT 2 April 9, 2015 08:01
how to understand high resolution scheme and high order scheme iilw1314 Main CFD Forum 3 September 30, 2010 10:43
High Aspect Ratio elements Flavio CFX 2 November 24, 2006 13:01
Multicomponent fluid Andrea CFX 2 October 11, 2004 05:12


All times are GMT -4. The time now is 01:28.