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

What's wrong with my RMS profile in LES

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 31, 2005, 04:30
Default What's wrong with my RMS profile in LES
  #1
Jiang Ning
Guest
 
Posts: n/a
I am now trying to simulate some channel flow with LES in fluent, but I met some porblem, and I am relly confused about that.

What I calculate is a very simple channel flow. The domain I chose is a cube with the size of 0.09+ACo-0.03+ACo-0.045m(x+ACo-y+ACo-z), the grid is 64+ACo-64+ACo-30. Air flow in x direction. the centre velocity is 8m/s. the inlet and outlet surface that normal to x direction is periodic condition(to simulate a very very long channel), the left and right surface(normal to z direction) of the cube is also the periodic condition, the top and bottom surface of cube is wall(no slip) condition.

I use the K-E model to calculate till it convergened, the result is used as the initial condition of the LES calculation. Then I switch to LES model(SGS model is simagorinsiki model), chose the PISO and centre difference in the discretization item. The time step fixed at 1e-5s. After 5e4 time steps, the mean velocity profile is quite similar to the theortic value.

My problem is the shape of the RMS velocity is quite different from the theortic analysis result. In y direction,it shoule be like , < ) <

but it is actrully like

< ( <

I tried many way to solve this problem, but I just can't find the solution. I think my grid is fine enough and the time step is small enough. I don't know what's wrong with my simulation.

Acturally I simulated several different cases, but non of them can get the correct rms profile.

Is here anybody suceed and get good rms profile? Any advise is welcome and highly appreciated.
  Reply With Quote

Reply

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
Unsteady Boundary Profile with data file Arianna FLUENT 26 March 24, 2014 06:55
LES and combustion model Margherita Cadorin CFX 0 October 29, 2008 06:24
Mapping RANS data onto an LES christian OpenFOAM Running, Solving & CFD 0 April 13, 2007 05:31
Prescribed inflow velocity profile - how to? Alan Main CFD Forum 10 October 28, 2005 12:14
Wind profile tom Phoenics 2 September 28, 2005 10:51


All times are GMT -4. The time now is 22:36.