# B.C's for k and omega

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

 January 11, 2002, 17:34 B.C's for k and omega #1 Suppe Guest   Posts: n/a Hi all. I'm currently working on implementing Wilcox's k-w model in my flow solver (PNS based). I'm having a lot of problem with the wall boundary condition - I am working on supersoinc turbulent flow past a flat plate. I have used k=0 at the wall, but my problem seems to be with the omega b.c for the wall. Could anyone suggest some good references/ideas please? Thanks!

 January 11, 2002, 18:06 Re: B.C's for k and omega #2 Jonas Larsson Guest   Posts: n/a I don't have any references with me here but I struggeld lot with this myself several years ago... If I remember correctly Wilcox has a wall-roughness model which gives an omega value based on a surface roughness. Using this model, with a surface roughness set to something which is essentially "smooth" was the most stable and best boundary condition that I found. I think that this is also what Wilcox recommends - the wall-roughness model is surely described in his book (Turbulence Modeling for CFD).

 January 11, 2002, 19:21 Re: B.C's for k and omega #3 Suppe Guest   Posts: n/a I did look at Wilcox's wall-roughness condition, but I was wondering if there was any other b.c for a smooth wall. I think I'll try out the rough-wall b.c anyway. Thanks for your input!

 January 12, 2002, 05:41 Re: B.C's for k and omega #4 Jonas Larsson Guest   Posts: n/a If you set the surface roughness paramater (if I remember it correctly Wilcox calls it kr+ or something) to a value well inside the viscous sublayer, say 1, the wall will be smooth - I did a sensitivity analysis on this a long time ago and found that for flows over turbine blades 1 was certainly enough to get a "smooth" blade. It is quite easy for you also to half the kr+ paramater and run againg just to verify that you get the same result.

 January 12, 2002, 12:16 Re: B.C's for k and omega #5 Suppe Guest   Posts: n/a That's a good suggestion. Thanks again for your reply.

 January 14, 2002, 11:18 Re: B.C's for k and omega #6 Dennis Guest   Posts: n/a The following reference may be of interest to you. Antti Hellsten: On the Solid-Wall Boundary Condition of omega in the k-omega-Type Turbulence Models, Technical Report, Helsinki University of Technology, Laboratory of Aerodynamics, Report B-50, Series B, 1998, ISBN 951-22-4005-X. Available on-line from: http://aeropc5.hut.fi/~ahellste/

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post cm_jubayer OpenFOAM 1 August 26, 2011 13:18 dancfd OpenFOAM Pre-Processing 0 June 9, 2011 23:25 sla FLUENT 0 January 10, 2011 05:16 john_w OpenFOAM Running, Solving & CFD 2 September 22, 2009 05:15 cbarry OpenFOAM 3 August 18, 2009 10:09

All times are GMT -4. The time now is 01:12.