I'm studying M.S. of mechanical eng. And my thesis is in the field of " Aerodynamic Drag Reduction ".as a part of my research I should simulate airflow around a bus in wind tunnel by the aid of fluent software. I've modeled the bus and wind tunnel in gambit software .then I exported it into fluent.

In fluent, there are some features which I am not sure about how to set them. For calculating turbulent kinetic energy, at first I should calculate the turbulence intensity (I) so I need to assume a good hydraulic diameter to calculate Reynolds no. Which length should be assumed as hydraulic diameter? For calculating turbulent dissipation rate I need turbulent length , how can I make a correct assumption for turbulent length? There is also a report menu bar in fluent environment which we should adjust some features like area, length, etc there in reference value option. In such a problem how should I adjust my reference values?

Hi amir which university you are studying? Have you studied FLUENT manual? mail me bye

I guess the dimension (length, area, etc..) in the Report-Reference Value menu is used for calculating force, flux, and others post processing value only. You just set the parameter of your problem case in the Define menu.