CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > Siemens > STAR-CCM+

Need help: 7 times more Mass Flow out than in

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 14, 2012, 12:31
Question Need help: 7 times more Mass Flow out than in
  #1
New Member
 
Simon
Join Date: Jun 2012
Posts: 4
Rep Power: 14
simonart7 is on a distinguished road
Hello!

I want to simulate the Battery-Cooling of a formula student car.
I implemented a radial fan, like in the rigid body motion tutorial

Inlet: Velocity (15m/s)
Outlet: Pressure
Implicit unsteady
Ideal Gas
K-Epsilon Turbulence
Gravity
Three Dimensional
Surface Remesher
Polyhedral Mesher
Prism Layer Mesher (2)

If I try Coupled Energy, the outgoing Mass Flow is going to be 7 times bigger than the incoming Mass flow.
It is still increasing.

Please help me!

Enjoy it.
Have a nice day!

( Please excuse my bad English)
simonart7 is offline   Reply With Quote

Old   June 14, 2012, 12:37
Default
  #2
New Member
 
Simon
Join Date: Jun 2012
Posts: 4
Rep Power: 14
simonart7 is on a distinguished road
How can I put pictures in here?
simonart7 is offline   Reply With Quote

Old   June 14, 2012, 12:38
Default
  #3
New Member
 
Simon
Join Date: Jun 2012
Posts: 4
Rep Power: 14
simonart7 is on a distinguished road
simonart7 is offline   Reply With Quote

Old   June 15, 2012, 04:33
Default
  #4
Member
 
Join Date: Mar 2009
Posts: 85
Rep Power: 17
husker is on a distinguished road
Hi,

Try to monitor mass flow rate with manual reports of density and velocity.

Regards
husker is offline   Reply With Quote

Old   June 15, 2012, 16:42
Default
  #5
Senior Member
 
Join Date: Oct 2009
Location: Germany
Posts: 636
Rep Power: 22
abdul099 is on a distinguished road
A mass flow report at each inlet and outlet should be fine to judge the mass imbalance.
How long did you run it? What about your time step size? Is it small enough? What about the convective courant number? Residuals? How does the flow field look like, is it reasonable?
In my experience, the coupled solver needs a long time until a reasonable flow field has established. So although CD-adapco recommends the coupled solver when ressources are no issue, I would stick to the segregated solver when there are no high mach numbers involved. Or at least try to initialise as good as possible.

When the setup is right and you run it long enough, the coupled solver will give you the same mass flow in and out for sure (assumed, you're looking on average values over a long enough period).
__________________
We do three types of jobs here:
GOOD, FAST AND CHEAP
You may choose any two!
abdul099 is offline   Reply With Quote

Reply

Tags
fan, invreasing mass, mass flow rate, rotating


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Convergence problem with target mass flow rate ADL FLUENT 2 May 29, 2012 22:11
Discrete Phase & Mass Flow Rate MagnusZeus FLUENT 0 December 2, 2011 18:57
Mass Flow Rate student87 CFX 4 January 2, 2010 05:45
mass flow Wenbin Song FLUENT 0 September 27, 2005 14:00
different mass flow rates michael FLUENT 4 February 21, 2005 04:48


All times are GMT -4. The time now is 17:19.