CFD Online Logo CFD Online URL
Home > Forums > OpenFOAM Running, Solving & CFD

Coarser mesh different pressure and velocity

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

LinkBack Thread Tools Display Modes
Old   February 20, 2008, 05:59
Default Hi, I am new to CFD. I am try
New Member
Anita K.
Join Date: Mar 2009
Posts: 25
Rep Power: 10
anita is on a distinguished road
I am new to CFD. I am trying to simulate Karman vortex street with flow around a trapezoidal body in 2D. The mesh is 8cm high and 15cm long. The trapezoidal body is 7.5mm high.
the boundaries are a inlet (10m/s), a outlet, and 2 symmetryPlanes. Because it is 2D the front and back are empty boundaries. As solver I chose IcoFoam.

I started with a mesh with approximately 25800 cells. And I got a good solution. I simulated 500ms and it needed 18 hours.

To get faster solutions I made the mesh coaser (5700 cells). And the calculation time was only 30min. I still get a nice karman vortex steet. But now the calculated pressure is lower (only half of the value) and also the velocity changed.

Now I don't know which result is right.
How fine must a mesh be to get good results?
Why does the results change, if I change refinement ?

How long does calculation normally take? I only have one DualCore computer.

Can someone help me?
Sorry for my bad English.


anita is offline   Reply With Quote

Old   February 20, 2008, 06:17
Default Boundary condition of the trap
New Member
Anita K.
Join Date: Mar 2009
Posts: 25
Rep Power: 10
anita is on a distinguished road
Boundary condition of the trapezoidal body is wall.
anita 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
VELOCITY PRESSURE sivaramakrishnaiah CFX 1 August 6, 2008 07:04
From pressure to velocity Rodrigo Madariaga Main CFD Forum 0 December 10, 2004 17:21
URF - Pressure, Velocity co2 FLUENT 0 May 11, 2004 21:36
UDF Pressure Velocity kendoo FLUENT 0 June 12, 2003 11:27
Pressure from velocity field Svante Hellzén Main CFD Forum 5 November 30, 1999 19:20

All times are GMT -4. The time now is 17:19.