YPlus
hi everybody, i am trying to simulate the surface temperature of a coupling enclosure. thus the heat comes from a rotating coupling (14000 rpm) and now my question is, do i have to use the reynold stress model and which value of Y+ should i have or is it enough when i am only using the kepsilon turbulence model? what are the values of Y+ for the kepsilon model? thanks, Florian

Re: YPlus
which kepsilon models do you want to use? high or lowReynolds number. for high reynolds number: y+ >= 20 and for lowreynolds y+ =< 2.
CFX/CFXTASCflow guys recommend to use komega instead of lowreynolds number model for kepsilon. all the best! Check the User manual. email me! 
Re: YPlus
thanks for your help. now i switched to the sstmodel with automatic wall function and with a value of about 100 for y+, that works quite good when i´m using the kepsilon model for the first 100 iterations.

Re: YPlus
The SST model with a Y+ on 100? I had the impression that the SST was a modified komega model, which basically means that Y+ should be small also with the scaled wall model ?? Any opinion?

Re: YPlus
thats right, the sst model is a mix of komega and kepsilon. in near wall regions the komega model is used and in the middle the kepsilon which can be seen when plotting the first blending factor where 1 means komega and 0 for kepsilon. I have read in an article on the cfx homepage that for sst model and automatic wall function any value for y+ between 2 and about 100 can be used, there will always be the same solution.

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