CFD Online Logo CFD Online URL
Home > Forums > CFX

general momentum source in cylindrical direction

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

LinkBack Thread Tools Display Modes
Old   May 31, 2006, 08:32
Default general momentum source in cylindrical direction
Posts: n/a
I'm modeling the turbine in pipe using actuator disc with wake rotation. I use 'Expression' to enter CEL in CFX-Pre. I define Smt, Smr, and Sma as the momentum source in tangential, radial, and axial direction, respectively. For example, Smt=-density*v*a/r. The axial direction coincide to the y-axis.

I use the 'General Momentum Source' with 'Cylindrical Componets' option. At 'Axis Definition' of 'Sources' tab, I choose 'Global Y' as the rotation axis.

However examining vector plot and contour plot from CFX-POST suggests that 'r' that I enter in 'Expression' might not be sqrt(x*x+z*z). Is this possible? and if it is, how can I fix this problem.
  Reply With Quote

Old   May 31, 2006, 09:05
Default Re: general momentum source in cylindrical directi
Posts: n/a
Dear Atit,

From the manual, r = sqrt(x*x+y*y) regardless of your axis.. r is the radial coordinate on the local frame where theta is measured from x and z is the axis.

If you want to access the cylindrical coordinates from an axis defintion you must use any of the triplets (raxis,taxis,aaxis). taxis is only available if you defined the axis using any of the local frame coordinate axis. This appeared in ANSYS CFX-10.0.

Hope this helps,

  Reply With Quote


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
pisoFoam compiling error with OF 1.7.1 on MAC OSX Greg Givogue OpenFOAM Programming & Development 3 March 4, 2011 18:18
Problem with Mass source, Momentum source theory diffo Fluent UDF and Scheme Programming 0 August 20, 2009 06:10
Momentum source Siva.K CFX 0 July 10, 2008 05:49
no enthalpy change across the momentum source Atit Koonsrisuk CFX 2 December 19, 2005 03:33
momentum source: continuity problems Johannes Radke CFX 2 December 17, 2004 05:21

All times are GMT -4. The time now is 10:02.