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

wall boundary condition

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

LinkBack Thread Tools Display Modes
Old   August 1, 2004, 04:59
Default wall boundary condition
Posts: n/a
I am coding a 3D RANS/k-eps cfd code and testing 2D now. In the flow solver at the wall I set the normal stress tauxx=tauyy=0 and tauxy=tauyx=tauwall (tauwall is based on the wall low). Is it correct? Who knows, who has experience? Thanks. WX.
  Reply With Quote

Old   August 19, 2004, 07:11
Default Re: wall boundary condition
Jonas Bredberg
Posts: n/a
Hi there,

You may either implement the wall friction as a source term in the code as: tau_w*A, where tau_w=rho*u_tau*U*kappa/ln(9*y+) from the law-of-the-wall and A is the wall-area using this routine you should override the normal routines in the momentum equation

or through a modified eddy-viscosity as: mu_eff=rho*u_tau*y*kappa/ln(9*y+) and include that instead of the normal eddy-viscosity.

The normal stresses are very small at the wall as: tau_xx=mu*dU/dx tau_yy=mu*dV/dy for which both the velocity gradients and the (effective) viscosity are small.

Cheers Jonas
  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
isothermal wall boundary condition Neil Main CFD Forum 3 November 9, 2015 03:34
How to set rotating wall as boundary condition babu FLUENT 7 December 14, 2013 05:48
Natural convection in a closed domain STILL NEEDING help! Yr0gErG FLUENT 3 June 12, 2013 02:12
Domain Imbalance HMR CFX 3 March 6, 2011 21:10
Variable temperature wall boundary condition Virginie FLUENT 2 October 2, 2007 09:23

All times are GMT -4. The time now is 07:30.