Near Wall Treatment for Y plus and getting mesh independent solution

HafizHafiz Member

I have thoroughly read about near-wall treatment and the use of wall functions vs near-wall model (EWT).

However, I am a bit confused when I applied them to my case. I am working on a 3D model of rotating disc reactor which is similar to the Taylor Couette reactor with internal flow between the coaxial discs. 

I have to run the simulations with several rotational speeds. With increasing rotational speed, the value of y+ increases. For example, one mesh which worked fine for low rotational speed and gave y+ < 5 with EWT, will definitely give higher y+ value. So should I conduct a mesh independence study for every rotational speed case? or just using a scalable wall function will be fine?

My concerns are:

1) If one gets a mesh independent solution with a mesh whose y+ value is greater then 30 ( y+ >30 ), a scalable wall function approach should be enough here? 

OR

2) we should still refine the mesh further to bring y+ value down to 1 in order to use EWT?

How should one follow two approaches side by side? That is, getting mesh independent solution and use of near-wall treatment.

I have attached my results of y+ value and velocity profile below for one case of higher rotational speed

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