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

How to trace source of divergence

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 3, 2003, 11:54
Default How to trace source of divergence
  #1
Jianjia
Guest
 
Posts: n/a
Hi there,

I am trying to model the viscous drag forces on the ship hull using standard wall function. I have managed to mesh the whole domain with hexahedral elements but it has rather high skewness at the bow and the stern. Approximately 0.8. Despite that, i can still get some results on drag coeff with an error of 20% with a min. y value of 0.01.

My question is this:- I tried to reduce the min y to 0.001 or even lower ti try to capture the turb boundary b-layer, and I my runs diverged. What could be the reasons? Did I hit into the viscous sublayer with my min. y spacing? How should i estimate the thickness? and how do i go about trying to identify the caused of divergence?

Any suggestions and comments are welcome. Thank you.

Very desperate... JJ
  Reply With Quote

Old   January 9, 2003, 06:53
Default Re: How to trace source of divergence
  #2
Boris
Guest
 
Posts: n/a
1) Do you use Gambit to mesh your domain? If yes, How can you achieve 0.8 skewness ?
  Reply With Quote

Old   January 9, 2003, 22:55
Default Re: How to trace source of divergence
  #3
Jianjia
Guest
 
Posts: n/a
Yes, I used Gambit to mesh my domain. The ship has a lot of curvature, esp. at the bulb and stern section, so that could be the cause of skewness. Could you suggest some methods in which i can reduce the skewness without compromising the ship's hullform. It would help grreatly. thanks
  Reply With Quote

Old   January 10, 2003, 06:48
Default Re: How to trace source of divergence
  #4
Boris
Guest
 
Posts: n/a
I have to learn from you about how to mesh the shipflow. The skewness is always over 0.9 while I do the meshing for shipflow when a single block domain is used. Could you kindly tell me how you decompose the domain, etc? Thank you so much.
  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
swak4foam building problem GGerber OpenFOAM Installation 54 April 24, 2015 16:02
wmake compiling new solver mksca OpenFOAM Programming & Development 13 August 18, 2014 22:26
pisoFoam compiling error with OF 1.7.1 on MAC OSX Greg Givogue OpenFOAM Programming & Development 3 March 4, 2011 18:18
DxFoam reader update hjasak OpenFOAM Post-Processing 69 April 24, 2008 01:24
DecomposePar links against liblamso0 with OpenMPI jens_klostermann OpenFOAM Bugs 11 June 28, 2007 17:51


All times are GMT -4. The time now is 04:25.