Objective of this project is to compare the results of two different Turbulence models i.e. K-epsilon and the SST -k- \omega. Requirements of two models are different and depends on the y+ value at the boundary.
Above figure shows the mean velocity distribution adjacent to a smooth wall, showing the logarithmic distribution away from the viscous region next to the wall and the linear region in the viscous sublayer.
Following link shows a fantastic discussion on various turbulence models:
From the above two links we understand that in case of k epsilon model, wall functions are used for the analytic flow calculation in the viscous sublayer near the wall. The technique offers good convergence and isn’t memory-intensive. In order to not resolve the viscous sub layer, y+ values are calculated and if the mesh satisfies 30 < Y+ < 300, then k-epsilon model and the wall functions are used.
For using the SST k-\omega, Y+ values are kept to the minimum i.e. y+~1 as this model resolves till the laminar sublayer.