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

LES of thermal plume

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

LinkBack Thread Tools Display Modes
Old   May 4, 2005, 19:17
Default LES of thermal plume
Posts: n/a
I am trying to simulate a thermal plume case with LES, which is based on a Smagorinsky model with a constant coefficient (Cs=0.1) and an eddy-diffusivity model for the turbulent heat flux, with a constant turbulent Prantdl number (Pr_t=0.72). The important paramters are Re=1000,Fr=1,Ma=0.2, and the temperature ratio of hot plume and the neviromental air is 3. The computational box is y=6(lateral direction),z=20(streamwise direction). The corresponding DNS grid I used is ny=320, nz=800. I tried a grid system which is ny=120, nz=400 for LES. But unfortunately it crashed. So far, I have tried to do many adjustments, like adjusting the model constants, switching off the model terms in enery equation for testing, artificially setting the SGS terms to be some part (20%) of rhs terms of the original equations for testing, but all failed. The only successful LES case I got is to use the same grid as in DNS. But it seems too strigent for me to use such a high grid resolution. I am even not sure if this is a numerical or physical problem. Will the buoyant effects in thermal plume require more considerations for a routine Smagorinsky model? Do you have any suggestions for this? Thanks a lot.
  Reply With Quote

Old   May 5, 2005, 12:27
Default Re: LES of thermal plume
Posts: n/a
Try reducing the time step by an order of magnitude. Let us know what that did.
  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
Constant velocity of the material Sas CFX 15 July 13, 2010 08:56
Turbulence dampening due to magnetic field in LES and RAS eelcovv OpenFOAM 0 June 8, 2010 11:35
Some Questions about LES. Bin Li Main CFD Forum 2 February 20, 2004 10:58
Short Course: Computational Thermal Analysis Dean S. Schrage Main CFD Forum 11 September 27, 2000 17:46
Info: Short Course On Thermal Design of Electronic Equipment Arnold Free Main CFD Forum 0 August 10, 1999 10:18

All times are GMT -4. The time now is 17:55.