[kartjo13]

Hi there,

I'm currently modelling the fluid flow from a catheter (100% saline) into a vein (100% blood) on Star CCM as part of my thesis project.

I've chosen the SST (Menter) K-Omega to model the turbulent regions as the saline interacts with the blood in the vein. I've selected the all y+ wall treatment model and kept my y+~1. I'm currently attempting to do a mesh independence study (GCI to be exact), however every time I increase my mesh by a refinement ratio of 2 (doubling the number of cells), my Max Wall Shear Stress (WSS), Average WSS and Std WSS drastically increases and results in my GCI values to very large for WSS. Also, I believe that my mesh is refined enough as i've gone up to 8,000,000 cells and still my WSS values are still increasing.

I've attached a picture of what I'm trying to model and also the WSS plots with each mesh refinement.

I'm a complete newbie when it comes to CFD and Star CCM+, so any pointers or words of advice would very much be appreciated (and the fact i don't know who else to ask).

Thank you in advance

[hokhay]

Interesting project, I think you should keep y+ the same and larger than 5 for all mesh size

[kartjo13]

Hi hokhay, may i ask why y+ should be kept larger than 5 for all mesh sizes?

Thanks.

[hokhay]

I am an OpenFoam user and the suggested y+ for kOmega SST is between 5 to 30 without special wall treatment. Maybe it is different for Starccm wall treatment. It's better to double check with the user guide