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

How do I prescribe Average Velocity /Total Inlet Flow for a simple channel problem?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   November 29, 2013, 14:59
Default How do I prescribe Average Velocity /Total Inlet Flow for a simple channel problem?
  #1
Member
 
Sergey
Join Date: Nov 2013
Posts: 86
Rep Power: 3
skuznet is on a distinguished road
I'm trying to make a simple case - flow through a channel with no-slip BC at boundaries of the channel.
I've prescribed fixedValue uniform velocity and zero gradient pressure at inlet.
At outlet I've prescribed fixedValue pressure. (p=0) and zeroGradient velocity.

I can run this case with these BC conditions, however velocity profile at inlet will be uniform and will not satisfy no-sleep BC and boundaries.

Is any way to prescribe average velocity or total flow at inlet to satisfy zero BC for velocities?

I was looking for the BC type here http://www.openfoam.org/docs/user/boundaries.php
but was not able to fine average velocity or total flow type.
skuznet is offline   Reply With Quote

Old   November 30, 2013, 08:15
Default
  #2
Senior Member
 
Nima Sam
Join Date: Sep 2009
Location: Tehran, Iran
Posts: 1,123
Blog Entries: 1
Rep Power: 14
nimasam is on a distinguished road
Send a message via Yahoo to nimasam
i guess you have two options :

1- using flowRateInletVelocity
Quote:

Example of the boundary condition specification for a volumetric flow rate:
\verbatim
myPatch
{
type flowRateInletVelocity;
volumetricFlowRate 0.2;
value uniform (0 0 0); // placeholder
}
\endverbatim

Example of the boundary condition specification for a mass flow rate:
\verbatim
myPatch
{
type flowRateInletVelocity;
massFlowRate 0.2;
rho rho;
rhoInlet 1.0;
}
\endverbatim
2- define a non-uniform inlet with :
groovyBC or code-stream
__________________
Training Course on OpenFOAM at (http://www.isme.ir/)
My Weblog (http://openfoam.blogfa.com/)
nimasam is offline   Reply With Quote

Old   December 1, 2013, 15:37
Default
  #3
Member
 
Sergey
Join Date: Nov 2013
Posts: 86
Rep Power: 3
skuznet is on a distinguished road
Salam!
Nima, thank you for you reply. I was able to run my case with inlet defined with keywords your suggested
Code:
type flowRateInletVelocity;
volumetricFlowRate;
However, the velocity profile is still uniform. Can I require velocities to satisfy no-sleep BC, i.e. zero velocities on the boundaries of the channel?
skuznet is offline   Reply With Quote

Old   December 1, 2013, 23:54
Default
  #4
Senior Member
 
Nima Sam
Join Date: Sep 2009
Location: Tehran, Iran
Posts: 1,123
Blog Entries: 1
Rep Power: 14
nimasam is on a distinguished road
Send a message via Yahoo to nimasam
i guess so ,
however if you applied no-slip condition and still you have uniform velocity, then you may want to try the second option
__________________
Training Course on OpenFOAM at (http://www.isme.ir/)
My Weblog (http://openfoam.blogfa.com/)
nimasam 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
y+ and u+ values with low-Re RANS turbulence models: utility + testcase florian_krause OpenFOAM 108 June 9, 2015 08:13
Steady pipe flow mean velocity higher than inlet velocity anita OpenFOAM Running, Solving & CFD 7 September 25, 2012 05:35
Turbulent flow through a pipe with variable inlet velocity lobstar OpenFOAM Running, Solving & CFD 8 March 28, 2012 11:15
Channel flow: Inlet pressure AND uniform velocity? frmap1 Main CFD Forum 0 April 15, 2010 10:32
velocity or mass flow inlet? Silvia FLUENT 1 August 12, 2005 13:55


All times are GMT -4. The time now is 00:34.