# turbulent velocity profile model ?

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 February 10, 2006, 04:33 turbulent velocity profile model ? #1 cfdq Guest   Posts: n/a I model a turbulent pipe flow which Re=5000 geometryvc3d 0 54.5 20 0 360 72 0 3862 500 using csys 2) at the inlet boundary W=-0.689025(for adjusting Re=5000) and turbulent intensity=0.05 turbulent length=0.001 Another setting is outlet boundary. also I give the geometry scalar factor=0.001(pipe radius =54.5 mm) so final result is as symbol "3" as following web site: http://www.wretch.cc/album/show.php?...1139464550&p=1 but what I want is trublent velocity profile as following web site http://www.wretch.cc/album/show.php?...1139464458&p=0 can anyone help me?

 February 13, 2006, 06:23 Re: turbulent velocity profile model ? #2 Yacine Guest   Posts: n/a use a longuer pipe in the streamwise direction or periodic boundary conditions and you will eventually end up with the profile you want after the solution is converged!!!!

 February 13, 2006, 10:49 Re: turbulent velocity profile model ? #3 cfdq Guest   Posts: n/a where to use periodic condition? In the theta direction?

 February 13, 2006, 12:04 Re: turbulent velocity profile model ? #4 cfdq Guest   Posts: n/a do you locate the wall boundary at the R(r)=Radius. or just treat it as defaults setting and needn't to set the wall boundary at the R(r)=Radius. thank you.

 February 13, 2006, 17:26 Re: turbulent velocity profile model ? #5 Alex Guest   Posts: n/a Not sure what you mean by that last post. Periodic boundary = Cyclic in STAR-CD language. You need a cylinder with cyclic boundaries on each end, so what goes out one end, comes in the other (or a longer pipe). Also, keep reducing your convergence tolerance. The changes on a iteration by iteration basis will be very small, so the default tolerance may be too large.

 February 13, 2006, 21:43 Re: turbulent velocity profile model ? #6 cfdq Guest   Posts: n/a can it use cyclic condiction in the z direciton in csys 2 (cylinder coordinate).using cyclic condition must be periodic repeating phenomenon.but pipe flow velocity is changing along the pipe(z direction) .does it work ?

 February 13, 2006, 22:04 Re: turbulent velocity profile model ? #7 cfdq Guest   Posts: n/a you mean orginal Max Residual Tolerance=0.001 .change it to 0.0001 (smaller).?

 February 14, 2006, 06:08 Re: turbulent velocity profile model ? #8 Anton Lyaskin Guest   Posts: n/a Actually it should be done in a bit different way - see Methodology, p. 5-8. What you need is a sector mesh (with cyclic boundaries in theta direction), only one cell long along the axis. At "inlet" you should apply uniform pressure and at outlet you should apply mass flow rate.

 March 6, 2006, 15:20 Re: turbulent velocity profile model ? *NM* #9 asmaa ahmed Guest   Posts: n/a

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