CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > CFX

Flow in a cavity

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

LinkBack Thread Tools Search this Thread Display Modes
Old   April 25, 2003, 06:41
Default Flow in a cavity
Posts: n/a
HI ! does anyone knows how to model a laminar flow in a cavity for 2Dimension. my tutor say i have to put the 'z' walls as a symetric wall/boundary. i am using CFX 5.5.1. could you one of you give me the hint?

The other think i tries to model this flow but however, i do not get the secondary vortex, only a main vortex.

anyway, thanks for your help whoever are you. i am just a new comer in fluid dynamics.
  Reply With Quote

Old   April 27, 2003, 18:30
Default Re: Flow in a cavity
Glenn Horrocks
Posts: n/a
Hi Herry,

Laminar flow in a 2D cavity is a good validation case to get you started in CFD. The laminar flow case is fairly easy to get a good solution for low Reynolds numbers (less than 1000), and a bit trickier for laminar flow above this Reynolds numbers. I used these cases as assignments in a CFD course at university I used to tutor. Getting good answers in the turbulent regime is quite a lot harder, and requires a high level of understanding of what's going on - if you're still at school I think getting a good answer in the laminar case should definitely be worth 10/10!

Anyway, typical things to look for in the laminar case to improve accuracy include:

1) Is the problem properly posed - dimensions correct? Flow driving velocity correct? Correct density and viscosity? Are you using the correct physics? If laminar then this is pretty simple.

2) Is it properly converged - all residuals to less than about 1E-4, and balances to better than 0.1%?

3) Is your mesh fine enough? Say run a 10x10 mesh, then a 20x20 mesh and if your solution does not change your solution is "mesh independant". If it does change run a 40x40 mesh, and keep refining the mesh until you do achieve mesh independance.

4) Are you running an accurate enough discretisation scheme? You are probably using the default first order scheme (Upwind). The "High Resolution" scheme is more accurate, but can be more difficult to converge. I assume you are not doing a transient simulation so I will not discuss these issues.

Anyway, I hope that helps.

Regards, Glenn
  Reply With Quote


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
2D Lid Driven Cavity Flow simulation using MATLAB josephlm Main CFD Forum 4 August 17, 2023 20:36
Reynolds Number matching in Cavity flow Endee Main CFD Forum 6 April 20, 2010 04:47
[blockMesh] basic blockMesh : manipulate the lid-driven cavity flow tutorials Lexa OpenFOAM Meshing & Mesh Conversion 2 November 12, 2009 21:15
Supersonic Flow over a Cavity (coodles): Maximum Iterations Exceeded sushant OpenFOAM Running, Solving & CFD 0 April 9, 2009 02:52
Inviscid Drag at subsonic, subcritical Mach # Axel Rohde Main CFD Forum 1 November 19, 2001 12:19

All times are GMT -4. The time now is 08:31.