[hellsblade.91]

I am trying to simulate the flow of air at at pressure of 6 bar as attached in the figure . I have maximum wall y+ value near the inlet (around 821)

As per fluent documentation the wall y+ function should be in the range of 30 to 300 for k epsilon model

When I change my edge sizing from 200 to 100 then wall y + reduces to 774 but still doesnt come in the appropriate range

Has anyone faced such a similar issue before

Also How does the solver compute wall y + value near the inlet

Wall y+ is typicaly the distance between the wall to the first node of boundary layer

I have 5 inflation layers across my 3 walls wherein the distance of the first layer is 1e-2 with a growth rate of 1.2

[Andrea1984]

y+ is the non-dimensional distance of the first cell-centre from the wall - the dimensional distance y is non dimensionalised by means of the friction velocity u_tau and the kinematic viscosity as y+ = y*u_tau/nu

Since nu is a physical property of the fluid and u_tau is related to the wall shear stress (and ideally should not depend on your mesh size), you are only left with the option of adjusting y (i.e. the height of your first prism layer) to meet the y+ requirements.

As a side comment, from the snapshot of your mesh that you have attached it really looks like you have a very abrupt transition (in terms of volume change) between prisms and core mesh. You might want to change your meshing parameters in order the have a smoother transition between the two regions.

Hope this helps,
Andrea