Hi @Hesham_Reda!
It seems that your domain (bounding box) is still too small and you did not use any inflation for your boundary layer. I would furthermore propose to use the parametric mesh option which gives you more options to adapt the mesh.
Once that is fixed try another run and let me know how the results vary.
Useful resources:
Tagging my colleagues @Get_Barried, @vgon_alves & @Anware here who might give you some additional tips.
Best,
Jousef