i've gone through many tutorial in the internet but still cannot mesh succesfully and use fluent to anaylze the cylinder. can anyone give me a step by step guide from making vertices to analysing it in fluent. the radius is 30.15mm. thank you

It depends on the Re number, At Re>100, you will probably observe the Von Karman street, which is a non stationary phenomena. So you should perform an unsteady simulation. But the Von Karman street is something difficult to simulate.

At lower Re number (say less than 50) the flow will probably be steady.

You can try a laminar approach with Fluent, but I'm affraid it may not converge. So a standard k-epsilon turbulence model could be used for initial trial.

For other details, it should be standard Fluent use.

Hope it helps.