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

non-uniform inlet velocity simulation in Fluent 13.0

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 24, 2013, 21:04
Default non-uniform inlet velocity simulation in Fluent 13.0
  #1
New Member
 
shuminhua
Join Date: Aug 2009
Posts: 3
Rep Power: 6
shuminhua is on a distinguished road
The performance of propeller is computing in Fluent 13.0. The inlet velocity which is non-uniform inflow was given using UDF in fluent. When I use turbulence model to simulate, the inlet velocity dissipated quickly (The plane close to the inlet whose velocity like the uniform). When I use Laminar or Inviscid model to simulate, there is no dissipation (the outlet velocity is similar to the inlet velocity)

Can someone give me a hint on how to do that ?

Thanks for your help !
shuminhua is offline   Reply With Quote

Old   October 25, 2013, 02:36
Default
  #2
Senior Member
 
Astio Lamar
Join Date: May 2012
Location: Pipe
Posts: 149
Rep Power: 4
asal is on a distinguished road
"The inlet velocity which is non-uniform inflow was given using UDF in fluent."

for this you should compile a UDF to impose a velocity profile through the inlet. or you need to use points!
For UDF you need to fit a polyline to the inlet profile velocity and then impose this polyline.

here is an example of the velocity profile UDF:

Quote:
#include "udf.h"

DEFINE_PROFILE(inlet_velocity, thread, position)
{
real z[ND_ND]; /* this will hold the position vector */
real y;
face_t f;

begin_f_loop(f, thread)
{
F_CENTROID(z,f,thread);
y = z[1];
F_PROFILE(f, thread, position) = 0.3-0.4*y+0.6*y*y;
}
end_f_loop(f, thread)
}

the red equation is the mentioned polyline.
asal is offline   Reply With Quote

Old   October 27, 2013, 20:17
Default
  #3
New Member
 
shuminhua
Join Date: Aug 2009
Posts: 3
Rep Power: 6
shuminhua is on a distinguished road
Thanks and sorry for my poor English.
In my case, I give the UDF in fluent and the inlet velocity shows from the velocity contours which seems to be no problem.
I use Inviscid and Laminar model (Viscous model) to simulate,the velocity of the sections parallel to the inlet are similar to the inlet velocity(the inlet velocity are non-uniform). But when i change viscous model to two equation turbulence model (SST , RNG),the velocity of the sections parallel to the inlet which are fully uniform(the dissipation are very quick).

thanks
shuminhua 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
Using a variable (increasing) inlet to get an easy convergence/initialization ? fredo490 OpenFOAM Running, Solving & CFD 8 April 9, 2014 09:35
second order schemes marine OpenFOAM 63 August 12, 2013 13:47
Air Conditioned room groovyBC Sebaj OpenFOAM 7 October 31, 2012 15:16
fluent inlet velocity setup linyx FLUENT 5 February 23, 2012 11:36
Channel flow: Inlet pressure AND uniform velocity? frmap1 Main CFD Forum 0 April 15, 2010 10:32


All times are GMT -4. The time now is 15:29.