CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > CFX

Need help defining a momentum source for a diffuser inlet

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

LinkBack Thread Tools Search this Thread Display Modes
Old   March 2, 2012, 14:23
Default Need help defining a momentum source for a diffuser inlet
New Member
Join Date: Jun 2010
Posts: 20
Rep Power: 15
serezhkin is on a distinguished road
Hi all,

I am trying to simulate a variable vane diffuser inlet using a momentum source method. The method works as follows:

(from Srebric, J. and Chen, Q. 2002. “Simplified numerical models for complex air supply diffusers,” HVAC&R Research, 8(3), 277-294.)

This momentum method de-couples momentum and mass boundary conditions for the diffuser in a CFD simulation. The diffuser is represented in the CFD study with an opening that has the same gross area, mass inflow, and momentum flux as a real diffuser. This model enables specification of the source terms in the conservation equations over the real diffuser area. The air supply velocity U0 for the momentum source term is calculated from the mass flow rate, mdot , and the diffuser effective area A0: U0=mdot/(A0*rho)

I am having trouble understanding how to implement the method.

So here are the steps I took:
1. Defined diffuser volume as a subdomain, with inlet side connected to the duct, and with outlet side connected the main volume.
2. Calculate the mass flow rate on the inlet side.
3. Outlet side. This is where I'm having trouble understanding what to do. How do I define a momentum source which would properly represent the air supply velocity?

Any suggestions would be appreciated.

I am attaching an image with proper implementation of the method in a different paper. The image shows where momentum source was applied, but unfortunately has no details whatsoever how exactly they did it so it's fairly useless for this discussion.
Attached Images
File Type: png Momentum method.png (42.6 KB, 75 views)

Last edited by serezhkin; March 2, 2012 at 14:40.
serezhkin is offline   Reply With Quote

Old   April 2, 2013, 12:20
New Member
Ma Jianjun
Join Date: Apr 2013
Posts: 1
Rep Power: 0
keeep0394 is on a distinguished road
Hi,I am now facing the same problem,have you worked it out?
keeep0394 is offline   Reply With Quote


Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
momentum source term zwdi FLUENT 14 June 27, 2017 15:40
Momentum source coefficient, cylindrical coordinates, circumferential component? polakse CFX 15 January 18, 2016 02:40
VOF source terms (Momentum and Mass)---How to define them ? cfdiscool FLUENT 0 February 13, 2010 21:10
OpenFOAM on MinGW crosscompiler hosted on Linux allenzhao OpenFOAM Installation 127 January 30, 2009 19:08
Inlet diffuser of ramjet Mohammad Kermani Main CFD Forum 25 December 29, 2000 18:46

All times are GMT -4. The time now is 12:21.