Reynolds number in Turbogrid

DDG · December 19, 2018, 06:28

I'm looking for suggestions:

In turbogrid it is possible to change the Reynolds number on which the mesh is based, then I was wondering, since I'm studying a transonic rotor both at Design point then off design conditions, if I should change the Re for the off design meshes, or if I could simply use the same mesh I've used at Design Point

Thank you in advance

ghorrocks · December 19, 2018, 16:37

Generate both meshes and see if the difference is significant.

DDG · December 20, 2018, 10:10

Thanks, actually I've done two simulations with two different Re (the one at DP and the one at OD) and I've checked the y+, there is an almost negligible difference between the two (the higher y+ changes from 1.1 to 1.3), so I think I will use the same mesh

hectorwerke · May 21, 2019, 20:21

Quote:

Originally Posted by DDG

Thanks, actually I've done two simulations with two different Re (the one at DP and the one at OD) and I've checked the y+, there is an almost negligible difference between the two (the higher y+ changes from 1.1 to 1.3), so I think I will use the same mesh

How can i check the y+ number.

AtoHM · May 22, 2019, 01:59

You can try to estimate it with the Re-Number and the first layer thickness you used, OR run a test simulation and get the values in CFD-Post.

DDG · May 22, 2019, 09:51

Quote:

Originally Posted by hectorwerke

How can i check the y+ number.

as AtoHM said, you can check the y+ with the Re number or in CFX Post, where you can plot the y+ diagram. Personally, I prefer the second option since it is more accurate

December 19, 2018, 06:28	Reynolds number in Turbogrid	#1
DDG New Member Join Date: Nov 2018 Posts: 15 Rep Power: 7	I'm looking for suggestions: In turbogrid it is possible to change the Reynolds number on which the mesh is based, then I was wondering, since I'm studying a transonic rotor both at Design point then off design conditions, if I should change the Re for the off design meshes, or if I could simply use the same mesh I've used at Design Point Thank you in advance

December 19, 2018, 16:37		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144	Generate both meshes and see if the difference is significant. DDG likes this. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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December 20, 2018, 10:10		#3
DDG New Member Join Date: Nov 2018 Posts: 15 Rep Power: 7	Thanks, actually I've done two simulations with two different Re (the one at DP and the one at OD) and I've checked the y+, there is an almost negligible difference between the two (the higher y+ changes from 1.1 to 1.3), so I think I will use the same mesh

May 22, 2019, 01:59		#5
AtoHM Senior Member M Join Date: Dec 2017 Posts: 694 Rep Power: 12	You can try to estimate it with the Re-Number and the first layer thickness you used, OR run a test simulation and get the values in CFD-Post.