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

re: Massflow reset in CFX 10

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 12, 2007, 14:12
Default re: Massflow reset in CFX 10
  #1
Wooster
Guest
 
Posts: n/a
Hi,

I'm inducing flow in a model via the massflow option. The massflow is 0.18 lbm/sec. This is inputted into the inlet and outlet (mass conservation). When the model is ready, it shows a proper distribution of massflow (equal throughout) but the inlet and outlet values are between 1E-4 and 3E-3 lbm/sec. I'm stuck trying to figure out how on earth 0.18 went to 0.001. Any suggestions? I feel as though there is some check box lurking in the background I should've checked. For troubleshooting, the inlet was setup with the massflow, the outlet condition was setup with a massflow and the "Scale Mass Flows". Thanks!

M
  Reply With Quote

Old   March 12, 2007, 15:14
Default Re: re: Massflow reset in CFX 10
  #2
Joe
Guest
 
Posts: n/a
Setting mass flow on both the inlet and outlet BCs is going to lead to issues.

Set a mass flow at the inlet and let the outlet calculate itself with an outlet-type BC.
  Reply With Quote

Old   March 12, 2007, 18:06
Default Re: re: Massflow reset in CFX 10
  #3
Wooster
Guest
 
Posts: n/a
What would you suggest the outlet condition to be? I would know most if not all the inlet conditions, but the outlet is an unknown. By forcing the massflow at the outlet I was thinking I'd have something to plug in. While its not a big thing with most of my models, there are a few where I need to setup a design and examine the differential pressure CFX calculates (outlet pressure/flow unknown).
  Reply With Quote

Old   March 12, 2007, 21:12
Default Re: re: Massflow reset in CFX 10
  #4
klarke
Guest
 
Posts: n/a
your question is not closed at all for such boundary conditon.(U,v,w,P),where is the p reference?
  Reply With Quote

Old   March 14, 2007, 22:51
Default Re: re: Massflow reset in CFX 10
  #5
HekLeR
Guest
 
Posts: n/a
ok, masflow outlet and total pressure inlet?? works fine if the flow is not choked.
  Reply With Quote

Old   March 16, 2007, 21:08
Default Re: re: Massflow reset in CFX 10
  #6
Wooster
Guest
 
Posts: n/a
Ok, I'm using for a particular model the inlet massflow (which is now working) and an outlet pressure condition of zero psi (good call Joe). This will work for this model. If there is a reference pressure (say 300 psi) how will the zero pressure outlet effect it? I have a model where I know some basic flow into the part, the reference pressure, but I know nothing of the outlet. In fact that is what I'm trying to figure out is whether the set of designs will improve dp and cooling of the device. Klarke, I don't know quite what you are asking. Now the model I'm working on has empirical data and so I'm busy benchmarking CFX against it. As for geometry, its a simple water jet blasting a hot plate. I have some volumetric heating questions but I'll save 'em for another thread. Thanks!

  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
Pros and Cons for CFX, CFdesign, COMSOL Val Main CFD Forum 3 June 10, 2011 02:20
MassFlow Function? Absolute MassFlow? Failure in Caclulation eRzBeNgEl CFX 0 May 5, 2011 09:46
CFX overpredicting turbine massflow sherifkadry CFX 3 February 1, 2010 04:15
PhD using CFX Rui CFX 9 May 28, 2007 05:59
CFX 4.4 installation problem Pandu Sattvika CFX 1 December 1, 2001 05:07


All times are GMT -4. The time now is 23:18.