[prince_pahariaa]

Dear friends

I am modeling turbulent flow heat transfer model. Re no is in the range of 30,000. Geometry is little complicated. Inlet is simple pipe flow and then it meet an hemispherical geometry in mid way and flow split. From top of hemispherical surface a solid vacuum tube is attached (there is no flow in the tube). Therefore, an annuls geometry formed from that point on.

Hemispherical geometry is little peculiar. It has the thickness of 1.5mm at mid point and 3mm at the top surface. It is again solid and modeled as a wall.

I have used k-epsilon model along with standard wall function in fluent.

My y+ values for the flow rate of 3kg/s is in the range 0f 30<y+<75 which is acceptable. but for flow rate of 35kg/s its range increase from 30<y+<745.

I have tried adapting the grid. And after that i get maximum y+ is 381 but i did not notice any change in my temperature profile. I have tried with k-omega model (which does not require wall function) and there also not much change.

My question is whether my modeling is valid inspite of y+>300 as my reynolds no is very large ?? If not what should be right range of y+. As 30<y+<300 is valid for flat plate... and my geometry is not different.

Also I did not understand why there is an upper limit for y+