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

How to get Pressure field from velocity field

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 13, 2007, 01:18
Default How to get Pressure field from velocity field
  #1
qunwuhe@hotmail.com
Guest
 
Posts: n/a
Once I got a flow field which is divergence free, how can I calculate the coresponding pressure field then I can get the pressure drop.

Thx
  Reply With Quote

Old   October 13, 2007, 09:04
Default Re: How to get Pressure field from velocity field
  #2
Jonas Holdeman
Guest
 
Posts: n/a
Given a divergence-free flow field, the "pressure Poisson" equation can be used to calculate the pressure from the velocity.
  Reply With Quote

Old   October 13, 2007, 21:23
Default Re: How to get Pressure field from velocity field
  #3
gocarts
Guest
 
Posts: n/a
Could apply Bernoulli's Theorem whereby:

Cp = (P - Pref) / (rho.Vref^2 / 2)

Cp = 1 - q^2 / Vref^2

where Cp = Pressure Coefficient, P = Static Pressure at x, Pref = Reference Static Pressure, rho = density, Vref = Reference Velocity Magnitude, q = Velocity Magnitude at x
  Reply With Quote

Old   October 14, 2007, 02:03
Default Re: How to get Pressure field from velocity field-
  #4
Adrin Gharakhani
Guest
 
Posts: n/a
This implies you know Cp. It also applies to particular physics (check basic fluid dynamics books). The pressure Poisson equation suggested By Jonas is the answer. Apply the divergence operator to the Navier-Stokes equation and use "continuity" for incompressible flow to get the source term for the Poisson equation

adrin
  Reply With Quote

Old   October 14, 2007, 07:38
Default Re: How to get Pressure field from velocity field-
  #5
gocarts
Guest
 
Posts: n/a
Of course you are both right on the Poisson equation being the most general solution for an incompressible flow.

However, for an invisid flow Bernoulli's is valid without knowing Cp - rearranging the original formula to eliminate Cp - gives static pressure directly as:

P = Pref + (rho / 2).(Vref^2 - q^2)

Given the original poster only specified they had a divergence free velocity field I presumed they may have obtained it from an inviscid methodology such as a panel method.
  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
problems after decomposing for running alessio.nz OpenFOAM 5 April 20, 2011 08:44
Channel flow: Inlet pressure AND uniform velocity? frmap1 Main CFD Forum 0 April 15, 2010 10:32
Pressure field in atmosphere Luc3er FLUENT 0 November 9, 2009 08:07
Velocity in Porous medium : HELP! HELP! HELP! Kali Sanjay Phoenics 0 November 6, 2006 07:10
Neumann pressure BC and velocity field Antech Main CFD Forum 0 April 25, 2006 02:15


All times are GMT -4. The time now is 21:29.