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

velocity magnitude and direction!!

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

Like Tree2Likes
  • 1 Post By CFD-fellow
  • 1 Post By LuckyTran

Reply
 
LinkBack Thread Tools Display Modes
Old   April 30, 2014, 16:12
Default velocity magnitude and direction!!
  #1
Senior Member
 
Astio Lamar
Join Date: May 2012
Location: Pipe
Posts: 154
Rep Power: 5
asal is on a distinguished road
Hello everybody.

I have a problem to set the velocity inlet boundary condition in form of "velocity magnitude and direction".

I want to introduce 2m3/s to my domain. So by having the inlet area I did the following:
2/inlet area = inlet velocity.
When this value assigned in the form and velocity, normal to boundary, I got the correct volume flow rate at the inlet.
But since the inlet velocity is not normal to boundary, I set the direction:

X-component of Flow Direction: 0.5627
Y-component of Flow Direction: 0.8267

then I got 1.65 m3/s in the inlet!!

Does anyone know what is the problem? why it is so? and what is the solution?
thanks.
asal is offline   Reply With Quote

Old   April 30, 2014, 17:44
Default
  #2
Member
 
Behrooz Jamshidi
Join Date: Apr 2013
Posts: 75
Rep Power: 4
CFD-fellow is on a distinguished road
Hi
According to your data i think your inlet face normal vector is in y direction.
When you say for normal velocity it is correct but for non normal velocity its not, this shows that Q/inlet area=inlet velocity is not a scalar equation its a vectorial equation.
For having 2m3/hr at face, you should set a volume flow rate so that its y (normal vector direction of your face) component equals 2m3/hr.
Regards
asal likes this.
CFD-fellow is offline   Reply With Quote

Old   May 1, 2014, 05:14
Default
  #3
Senior Member
 
Lucky Tran
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 606
Rep Power: 12
LuckyTran is on a distinguished road
As the person before me suggested, the x,y,z-component of flow direction are the scalar components of the flow vector. Each of those components carry the units (default is m/s).

Depending on which plane your inlet lies in, you need to specify the right x or y component velocity to get the desired volumetric flowrate. And then specify the other component to get the desired direction.
asal likes this.
LuckyTran is offline   Reply With Quote

Old   May 2, 2014, 03:12
Default
  #4
Senior Member
 
Astio Lamar
Join Date: May 2012
Location: Pipe
Posts: 154
Rep Power: 5
asal is on a distinguished road
Hello and thanks for your reply.

@ LuckyTran: Would you please advice how can I set the correct x and z component of velocity to have 2m3/s flow rate on the inlet? degree = 30

Last edited by asal; May 6, 2014 at 11:31.
asal 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
Air diffuser velocity magnitude and direction kenzosenzo FLUENT 17 March 31, 2014 07:03
Variable Velocity Inlet magnitude and direction Brendan FLUENT 0 March 24, 2014 07:24
Natural convection in a closed domain STILL NEEDING help! Yr0gErG FLUENT 3 June 12, 2013 02:12
Paraview - 2d vector glyphs colored by vector direction & magnitude newOFuser OpenFOAM 1 December 19, 2011 19:34
what the result is negatif pressure at inlet chong chee nan FLUENT 0 December 29, 2001 06:13


All times are GMT -4. The time now is 18:44.