Yes, you can easily plot the value of y+ on the plot function of turbulence. There is "wall y plus" option.

Dear Ahmed,

The following website has extensive questions and discussions about CFD. I think this can be useful for your problem.

https://www.cfd-online.com/Forums/ansys/

30 < y+ < 300 for a fully turbulent portion or log-law

region.

Dear Ahmed,

You can find the answer over here:

https://www.researchgate.net/post/y_plus_range_for_turbulent_models

Many thanks for all

Please refer this link:

http://www.cfd-online.com/Tools/yplus.php

Hi dear Ahmad, Thank you for your comment. As I mentioned in the description in Fig. 4 in last paper:

Article Study of the sneezing effects on the real human upper airway...

I have come to the experimental conclusion that in the respiratory system, the thickness of the boundry layer is often less than 2mm.

1) If you want to know the results from the fluent simulation of y +, you can choose contour>turbulence>y+,

2) if you want to know how to assess the height of the first layer of boundary wall, you can have the links above to calculate it.

Thanks.

Thanks for all

Very Interesting topic. I am want to highlight that are very important next limits of y+ or y* (y star) for your correct use with RANS turbulent models:

• y+11 for k-e with Scalable Wall Functions.
• 30
  2 votes 2 thanks

Many thanks Leonardo for your answer

Yes, you can easily plot the value of y+ on the plot function of turbulence. There is "wall y plus" option.

Do check out @Hamed Majidian's answer here -

https://www.researchgate.net/post/y_plus_range_for_turbulent_models

Dear Sudharshan Selvaraj ,

let me thank you in advance for your attention. Dear Ahmed Ramadhan Al-Obaidi first thing on the ground is we cannot consider the application of Y+ equally for all of the turbulent models since some of them are not formulated on this basis for example, as you certainly know LES or Reynolds stress models do not use Y+. In addition, it ought to be noted that the application of Y+ for RANS models heavily depends on the Reynolds number, your previous information about the flow regime, and the shape of the bluff body. Now before getting dipper let me review what the Y+ is. Y+ is an auxiliary profile for the description of phenomena in boundary layers in terms of equilibrium between inertia and viscosity. In other words, using Y+, we consider a pre-defined profile for the viscous sublayer and buffer layer where the viscous force deemed to be dominant relatively. In this order, the directional velocity such as u,v,w assumed to be zero as the source of turbulent flow. Besides, dp/dx assumed to be 0, for the profile is considered to be authentic for two-dimensional ordinates (flat plate). So as we can see Y+ is very intricate and only could be used if we consider how it should be used. As one of the RANS turbulent pioneer models, K-epsilon suits for high Reynolds numbers and K-omega suits for low Reynolds number. A combination of both in the switching model could be employed for most of the flow regimes, though, it might be unstable in terms of residuals. Nevertheless, before allocating Y+ we have to calculate boundary layer thickness and viscous sublayer thickness. Two formulas are available, though others might exist. Boundary layer thickness= 0.37 x length /(Re)^1/5 and for viscous sublayer=11.6*viscousity kinematic/u*, and u*=(fractional stress/density)^1/2. After calculation the log law region where you have star your grids are0.02

Please refer the following article https://www.linkedin.com/pulse/understanding-y-cfd-simulation-sijal-ahmed/

Many thanks

For each model, FLUENT can plot y plus for you (X-Y Plot).