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

Help:Finding sources of error

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 25, 2005, 22:31
Default Help:Finding sources of error
  #1
Quarkz
Guest
 
Posts: n/a
Hi,

I've written a NS FVM solver. I'm using Ghia's lid driven cavity result to test for accuracy.

The u values for the same grid size typically have difference of less than 2%, except one which is different by 20% (0.003 vs 0.004).

However, the v values typically have difference of 2-5%. I'm wondering if that is acceptable...

I'm trying to find out the source of error. I was thinking of wrong implementation of BC but then my u values will not be so close then. Hence I suspect that there are some careless mistakes in my v,y BC. Is that logical since my v values differs by 2-5%?

Thank you very much
  Reply With Quote

Old   July 26, 2005, 11:00
Default Re: Help:Finding sources of error
  #2
M
Guest
 
Posts: n/a
Firstly, if You would like to get help here, please give description of Your solver.

NS FVM solver rather wide formulation

When I had the same problem, I fixed it having found a mistake in high-order discretization schemes of convective terms (there was a bug).

With BC there have not to be problems

U and V all zero except upper wall where U=1.

As a rule on the fine grid (300x300) with HLPA scheme You should obtain excellent results

All that from my experience with SIMPLE solver on staggered as well as colocated grids
  Reply With Quote

Old   July 26, 2005, 11:03
Default Re: Help:Finding sources of error
  #3
M
Guest
 
Posts: n/a
By the way, how do You get Ghia's velosity distribution?
  Reply With Quote

Old   August 2, 2005, 05:29
Default Re: Help:Finding sources of error
  #4
quarkz
Guest
 
Posts: n/a
what do you mean by how to get Ghia's velosity distribution?

the velocities are given in his paper in journal of computational physics 1982 48 p387
  Reply With Quote

Reply

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
Compile problem ivanyao OpenFOAM Running, Solving & CFD 1 October 12, 2012 10:31
OpenFOAM install on Ubuntu Natty 11.04 bkubicek OpenFOAM 13 May 26, 2011 06:48
Accessing phi from a fvPatchField at same patch johndeas OpenFOAM 1 September 13, 2010 21:23
Problem with compile the setParabolicInlet ivanyao OpenFOAM Running, Solving & CFD 6 September 5, 2008 21:50
Compiling problems with hello worldC fw407 OpenFOAM Installation 21 January 6, 2008 18:38


All times are GMT -4. The time now is 08:15.