# les-ras
- d
dendri
07/07/2021, 7:07 PMHi everyone! I'm doing some asymptotic expansion of k-omega equations and through some manipulation I got two constants: about 0.41 and about 2.66 - d
dendri
07/07/2021, 7:07 PMI recognised the first one as the Von Karman's constant, so it made me wonder if there is some other constant around the value if 2.66 - d
dendri
07/07/2021, 7:07 PMDoes anything come to someone's mind please? :) - u
uemalkocoglu
07/07/2021, 7:21 PMShould be B*kappa ? - u
uemalkocoglu
07/07/2021, 7:22 PMI remember this around 2.35 though - d
dendri
07/08/2021, 12:43 PM@uemalkocoglu sorry, I just saw this! Could you tell me what B and kappa you're referring to please? - u
uemalkocoglu
07/10/2021, 10:03 AMNo problem @dendri - u
uemalkocoglu
07/10/2021, 10:04 AMI was just mentioning logarithmic region equation for law of the wall - u
uemalkocoglu
07/10/2021, 10:04 AMThis equation has the form: - u
uemalkocoglu
07/10/2021, 10:05 AMu+ = (1/kappa)*(ln(y+)) + B - u
uemalkocoglu
07/10/2021, 10:06 AMHere; - kappa is von Karman constant, which is stated as 0.4-0.42 in several resources - B is another constant and its value is around 5.0-5.5 depending on surface roughness situation - u
uemalkocoglu
07/10/2021, 10:07 AMIf I made mistake, let anyone make me correct please - d
dendri
07/10/2021, 10:08 AMOh I see, thank you :) I don't think that's it in my case then. I got these constants from a specific combination of wilcox's k-omega parameters - d
dendri
07/10/2021, 10:10 AM$ \kappa = \frac{\sqrt{\beta - \alpha \beta^*}}{\sqrt{\sigma} \beta^*^{1/4}} \approx 0.41$ - d
dendri
07/10/2021, 10:11 AMThat didn't work :) - d
dendri
07/10/2021, 10:12 AMAnyway, I wouldn't be surprised if there wasn't a constant for that value of around 2.66 that I got. It just made me.wonder since I got von Karman - d
dendri
07/10/2021, 10:12 AMThanks again @uemalkocoglu :) - u
uemalkocoglu
07/10/2021, 10:46 AMNot at all @dendri , good luck - d
dendri
07/10/2021, 10:46 AMThanks! - t
thewhencat
07/16/2021, 6:58 PMHey yall, so im running a RAS HVAC simulation and im running a test input velocity of 1.5 m/s. With pressure outlets the solved (and well converged) velocity fields are in the magnitude of 100s or 1000s m/s. Has anyone come across a similar problem here? - s
slopezcastano
07/19/2021, 7:51 AM@User Who is "yall"? - u
uemalkocoglu
07/19/2021, 9:50 AM"You all"? - u
uemalkocoglu
07/19/2021, 9:51 AMIf you are asking seriously - s
slopezcastano
07/19/2021, 3:03 PMWhy wouldn't I ask seriously? - u
uemalkocoglu
07/19/2021, 3:04 PMYeah, you are right - u
uemalkocoglu
07/19/2021, 3:05 PMI thought you may be familiar with slanga - u
uemalkocoglu
07/19/2021, 3:05 PM*slangs - t
thewhencat
07/19/2021, 3:36 PMoh sry ye I use y'all instead of you all; very convinient piece of slang - t
thewhencat
07/19/2021, 10:39 PMhey yall, sry another question, but has anyone run into a bounding omega problem where it massively diverges (1000 or higher) with negative values? i get a smiilar problem in epsilon if i do a k-epsilon model (am running k-wSST as primary or one above) - t
thewhencat
07/19/2021, 10:39 PMsomething like this