turbulent juncture flow around cyl mounted on flat plate
 

hi there
I am simulating turbulent juncture flow around a cylinder mounted vertically on a flat plate in fluent 14.0, and range of Reynolds number is 8000-100000 I need few guidelines
what time step size should i use to get a converged solution and how to calculate step size ?
which viscous model is better to use for this range ?
what steps should i follow to get better results ?

mesh size is 2.18 million