|
[Sponsors] |
December 16, 2004, 10:33 |
ystar and yplus
|
#1 |
Guest
Posts: n/a
|
Posted By: Abhijeet Vaidya <vabhi@hotmail.com> Date: Tue, 29 Oct 2002, 10:25 a.m.
hi friends, You must be aware of ustar & yplus as fluent defines it ! Going by their definitions , I was thinking that they should be exactly same if ystar is > 11.25. But when I solved turbulent flow over an expanding channel (pl note that this is a benchmark problem for laminar flow so the geometry of this channel must be familier to the readers), then yplus goes to zero at the reattachment poing which is obvious but even in the regions where ystar is > 11.25 , there is difference in the value of ystar and yplus which means that even when ystar > 11.25, still u_tau = (cmu^0.25)*(tke^0.5) does not hold ? But theory says otherwise ! Can somebody help ? |
|
December 16, 2004, 12:19 |
Re: ystar and yplus
|
#2 |
Guest
Posts: n/a
|
They should be close to each other in equilibrium boundary layers where u_tau =(Cmu^0.25)*tke^0.5 is a good approximation. In non-equilibrium flows (e.g., diffusers you're considering), however, they can be quite different. A quintessential example is reattchment or stagnation point where u_tau and therefore y+ vanishes (tau_w = 0), yet TKE has a finite, usually quite large value there making ystar finite.
|
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Macros for yplus, ystar, Ustar | Seppl Huber | FLUENT | 6 | October 12, 2020 05:26 |
Yplus and ystar | guido_adriaensen | OpenFOAM Post-Processing | 17 | April 21, 2019 04:44 |
yPLUS vs. ySTAR | bastil | OpenFOAM Bugs | 1 | March 14, 2012 05:00 |
How to access yPlus in UDF | Alexander | FLUENT | 0 | March 14, 2008 13:09 |
ystar and yplus | sarah_ron | FLUENT | 2 | July 4, 2005 11:51 |