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

Different ans of poisson eqn with different solver

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

LinkBack Thread Tools Display Modes
Old   October 6, 2005, 11:49
Default Different ans of poisson eqn with different solver
Posts: n/a

I am trying to solve a simple laminar channel flow, uniform velocity in, supposedly parabolic profile out. hence, u=1 at west face inlet, no-slip at wall, convective BC at outlet.

since i'm using FVM fractional step, i need to solve a poisson eqn after the momentum eqn. however, i can't get a converged ans with iterative solve such as GMRES using NSPCG. When I used direct solver, such as IMSL library dlslrg (gaussian) or LAPACK 's dgesv (LU decomp), i get the same ans for both at the 1st step, but different ans after that. I'm wondering if there's something wrong with my BCs, which can be one of these:

1. dp/dx at all 4 sides, p=0 at outlet, others extrapolated 2. dp/dx at all 4 sides, p at edge face extrapolated 3. dp/dx at all except outlet, p=0 at outlet, others extrapolated

Can anyone tell me the fault? thanks

  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
4th order accurate pressure poisson solver srinivas Main CFD Forum 4 February 28, 2009 06:23
Data Structures - 2D FVM Euler Eqn Solver Scott Main CFD Forum 3 March 31, 2006 06:09
Recommendation of a good poisson solver Quarkz Main CFD Forum 2 December 2, 2005 10:12
Solver for poisson eqn in FVM? Mudpack, fishpack.? zonexo Main CFD Forum 0 October 5, 2005 19:11
Poisson Solver question Suresh Main CFD Forum 3 August 12, 2005 04:37

All times are GMT -4. The time now is 13:05.