Which yplus (Max,ave,volumeAve?) value do I need from CFD Post

gillers18 · July 4, 2017, 07:28

I want to determine the y+ value from the simulation of a T-junction pipe in Ansys Post. When I plot the y+ value it ranges from 0 to 10, because there are some local regions where the y+ value is high. To solve this problem, I tried to refine these regions in ICEM further like I read in a previous post here but it led to bad elements and to a higher aspect ratio (>200). The first cell height is curretly 0.03 mm and the aspect ratio 167. I want to get a y+ < 5 for an LES-Simulation. My question is: Is the maximal y+ value (10) more relevant or can I just consider either the average (ave) of y+ on the Wall or the Volume average (volumeAve) of y+ on the domain, which are both < 5 as the y+ value that I need. I am not sure which y+ value I need. Thx in advance for your help.

ghorrocks · July 6, 2017, 06:57

Then why not try a range of y+ values and find out whether you are sensitive to it or not? Rather than guess, test it out and find the real answer.

July 4, 2017, 07:28	Which yplus (Max,ave,volumeAve?) value do I need from CFD Post	#1
gillers18 New Member Join Date: Feb 2015 Location: Stuttgart Posts: 7 Rep Power: 11	I want to determine the y+ value from the simulation of a T-junction pipe in Ansys Post. When I plot the y+ value it ranges from 0 to 10, because there are some local regions where the y+ value is high. To solve this problem, I tried to refine these regions in ICEM further like I read in a previous post here but it led to bad elements and to a higher aspect ratio (>200). The first cell height is curretly 0.03 mm and the aspect ratio 167. I want to get a y+ < 5 for an LES-Simulation. My question is: Is the maximal y+ value (10) more relevant or can I just consider either the average (ave) of y+ on the Wall or the Volume average (volumeAve) of y+ on the domain, which are both < 5 as the y+ value that I need. I am not sure which y+ value I need. Thx in advance for your help.

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July 6, 2017, 06:57		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,716 Rep Power: 143	Then why not try a range of y+ values and find out whether you are sensitive to it or not? Rather than guess, test it out and find the real answer.