CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum

mesh size: getting worse results with finer mesh

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

LinkBack Thread Tools Display Modes
Old   June 10, 2015, 05:08
Question mesh size: getting worse results with finer mesh
New Member
Ali Adel
Join Date: Nov 2014
Posts: 6
Rep Power: 5
AliZuhaira is on a distinguished road
Hello everybody,
I am using a model which is dealing with the turbulence and waves, the problem when I made the validation for the programme with the experiment data, it showed a good result; however, when i reduced the mesh size to get more accurate solution, the results getting far from the experiment data and the relative error between the experiment data and the numerical result increased and reached to 50% (when i used small mesh size)
why that happened????
any explain for that case??
Thank you in advance for any answer,
AliZuhaira is offline   Reply With Quote

Old   June 11, 2015, 07:11
Senior Member
RodriguezFatz's Avatar
Join Date: Jun 2011
Location: Germany
Posts: 1,297
Rep Power: 20
RodriguezFatz will become famous soon enough
Possible reasons (among others):
  • Your fine mesh has lower quality for some reason. Thus, the solution is worse.
  • Your coarse mesh solution coincidentally equals the measured / correct values. Maybe because some errors cancel each other. When the grid becomes finer, numerical error decreases and the errors don't cancel each other any longer.
  • Your solution is not converged regarding grid size (not grid independent).
Anyway, after checking the first point, can you afford to run an even finer mesh?
The skeleton ran out of shampoo in the shower.
RodriguezFatz is offline   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
Gambit problems Althea FLUENT 22 January 4, 2017 04:19
Moving mesh Niklas Wikstrom (Wikstrom) OpenFOAM Running, Solving & CFD 122 June 15, 2014 06:20
2D Mesh Generation Tutorial for GMSH aeroslacker Open Source Meshers: Gmsh, Netgen, CGNS, ... 12 January 19, 2012 04:52
Phase locked average in run time panara OpenFOAM 2 February 20, 2008 15:37
How to control Minximum mesh space? hung FLUENT 7 April 18, 2005 09:38

All times are GMT -4. The time now is 14:10.