y+

Francesco1951 · December 28, 2014, 12:11

Dear all,

I'm a new user. I'd like to know how to estimate the y+.

Greetings

AntonZ44 · January 4, 2015, 17:01

Here is an online tool

Here are the formulae used

You can check y+ after some iterations and then go back to adjust your mesh accordingly too.

Francesco1951 · January 5, 2015, 09:20

thanks for your reply!

I can understand that is an iterative process, but I'd like to know how to estimate the first y+ value. Could you help me to find a solution?

Greetings

lcarasik · January 5, 2015, 17:36

Quote:

Originally Posted by Francesco1951

thanks for your reply!

I can understand that is an iterative process, but I'd like to know how to estimate the first y+ value. Could you help me to find a solution?

Greetings

AntonZ44 already provided a means to get a rough estimate of your first half cell height based on the required y+ value. Keep in mind this does approximate your geometry as a flat plate. I'm not sure what you're asking for at this point.

Francesco1951 · January 6, 2015, 02:58

I don't know the required y+ value

. Where and how can I calculate the require y+.

feafan · January 7, 2015, 00:27

Quote:

Originally Posted by Francesco1951

I don't know the required y+ value

. Where and how can I calculate the require y+.

Just click on the links in post #2.

vivekcfd · January 15, 2015, 16:23

Is it internal flow problem or external aerodynamics? Please elaborate more what kind of problem you are solving.

Francesco1951 · January 16, 2015, 02:10

It's a resistance prediction for a ship

vivekcfd · January 19, 2015, 11:27

You may use cf = 0.664/Re^(1/2) for Laminar boundary layer and 0.0227/Re^(1/7) for turbulent boundary layer. From cf it is quite straight forward to calculate tau_wall and hence y+ using definitions in http://www.cfd-online.com/Wiki/Y_plu...nce_estimation

December 28, 2014, 12:11	y+	#1
Francesco1951 New Member Francesco Join Date: Sep 2014 Posts: 7 Rep Power: 11	Dear all, I'm a new user. I'd like to know how to estimate the y+. Greetings

January 4, 2015, 17:01		#2
AntonZ44 New Member Anton Zhyzhyn Join Date: Feb 2013 Posts: 13 Rep Power: 13	Here is an online tool Here are the formulae used You can check y+ after some iterations and then go back to adjust your mesh accordingly too.

January 5, 2015, 09:20		#3
Francesco1951 New Member Francesco Join Date: Sep 2014 Posts: 7 Rep Power: 11	thanks for your reply! I can understand that is an iterative process, but I'd like to know how to estimate the first y+ value. Could you help me to find a solution? Greetings

January 6, 2015, 02:58		#5
Francesco1951 New Member Francesco Join Date: Sep 2014 Posts: 7 Rep Power: 11	I don't know the required y+ value . Where and how can I calculate the require y+.

January 15, 2015, 16:23		#7
vivekcfd Member Vivek Kumar Join Date: Mar 2009 Location: Switzerland Posts: 35 Blog Entries: 1 Rep Power: 17	Is it internal flow problem or external aerodynamics? Please elaborate more what kind of problem you are solving.

January 16, 2015, 02:10		#8
Francesco1951 New Member Francesco Join Date: Sep 2014 Posts: 7 Rep Power: 11	It's a resistance prediction for a ship

January 19, 2015, 11:27		#9
vivekcfd Member Vivek Kumar Join Date: Mar 2009 Location: Switzerland Posts: 35 Blog Entries: 1 Rep Power: 17	You may use cf = 0.664/Re^(1/2) for Laminar boundary layer and 0.0227/Re^(1/7) for turbulent boundary layer. From cf it is quite straight forward to calculate tau_wall and hence y+ using definitions in http://www.cfd-online.com/Wiki/Y_plu...nce_estimation