Learning Forum

[scabo]

Hi, I am slightly confused with y+ values for different turbulence models. For k-e mode, y+ is around 30-300 and for k-w it is around 1. Is that correct? For RSM models based on k-w, the y+ should be around 1 right? And also, for RSM models, based on k-e, y+ should be around 30. Am i correct? In short I want to know, if I am choosing RSM model , BSL and Linear Pressure Strain, what will be the y+ values and wall funtions? Should i choose standard or scalable wall functions?  thanks, any help is appreciated.

[rademacherdacostacabral.v]

Hi, the documentation regarding this subject is pretty well written in my opinion. As far as I understand the k-e-model must be used with a wall function as it can not compute the boundary layer by itself even when using a mesh with very fine resolution (low y+).

K-w-model is more flexible as it can do both:
"Ideally simulations should be computed with meshes where is 1 , however this requirement is not always easy to achieve, especially in industrial computations at high Reynolds numbers and with complex geometries. It is also not always possible to create pure wall function meshes with > 30 on the entire geometry. Wall-formulations have therefore been developed which smoothly blend between the two limits. Such formulations are termed "-insensitive near-wall treatment"."
- https://ansyshelp.ansys.com/public/account/secured?returnurl=///Views/Secured/corp/v242/en/flu_th/section_kbf_dl4_vvb.html

https://ansyshelp.ansys.com/public/account/secured?returnurl=//Views/Secured/corp/v242/en/flu_ug/flu_ug_k_epsilon_setup.html
https://ansyshelp.ansys.com/public/account/secured?returnurl=//Views/Secured/corp/v242/en/flu_ug/flu_ug_k_omega_setup.html