y+ (respecting the estimated wall distance)

zomayabssa · May 28, 2014, 17:21

Hi,

When you got for example an estimated wall distance of 5E-6 using the CFD ONLINE tool, does it matter if you use a smaller value in your mesh such as 3E-6 or the mesh has to begin exactly from the estimated value?
Thanx in advance guys,

Loffy

ahmed_khatibs · May 29, 2014, 03:35

CFD online helps you to approximate the values, you may get help:

http://www.cfd-online.com/Forums/mai...lus-value.html

regards,
Ahmed Khatib

harishg · June 1, 2014, 12:47

For turbulence models which can be used in the visous layer, having y+<=1 can ensure convergence of results. So having a smaller value is fine. However, some of the models may have certain restrictions on the validity of their damping functions/ corrections. You might need to check the documentation for the specific model.

zomayabssa · June 5, 2014, 14:39

Thnx for these suggestions guys!

jthiakz · June 6, 2014, 00:26

sometime it is possible with meshing tools, but after importing in solvers with some low tolerance, it might show some errors.., so make sure you have fine mesh with reasonable quality. let us know if it works.

Also refer the turbulence modeling requirements.

May 28, 2014, 17:21	y+ (respecting the estimated wall distance)	#1
zomayabssa New Member LOTFI OULD ROUIS Join Date: Jan 2014 Location: Canada Posts: 23 Rep Power: 12	Hi, When you got for example an estimated wall distance of 5E-6 using the CFD ONLINE tool, does it matter if you use a smaller value in your mesh such as 3E-6 or the mesh has to begin exactly from the estimated value? Thanx in advance guys, Loffy

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May 29, 2014, 03:35		#2
ahmed_khatibs Member ahmed Join Date: Sep 2011 Location: Pune-INDIA Posts: 34 Rep Power: 15	CFD online helps you to approximate the values, you may get help: http://www.cfd-online.com/Forums/mai...lus-value.html regards, Ahmed Khatib

June 1, 2014, 12:47		#3
harishg Senior Member N/A Join Date: Mar 2009 Posts: 189 Rep Power: 17	For turbulence models which can be used in the visous layer, having y+<=1 can ensure convergence of results. So having a smaller value is fine. However, some of the models may have certain restrictions on the validity of their damping functions/ corrections. You might need to check the documentation for the specific model.

June 5, 2014, 14:39		#4
zomayabssa New Member LOTFI OULD ROUIS Join Date: Jan 2014 Location: Canada Posts: 23 Rep Power: 12	Thnx for these suggestions guys!

June 6, 2014, 00:26		#5
jthiakz Member Thiagu Join Date: Oct 2012 Location: India Posts: 60 Rep Power: 14	sometime it is possible with meshing tools, but after importing in solvers with some low tolerance, it might show some errors.., so make sure you have fine mesh with reasonable quality. let us know if it works. Also refer the turbulence modeling requirements.