Y Plus
 

Can we calculate Y plus for laminar flow?
if yes; then please guide me in that...

If you look at the formulation of y plus, it resembles something of a turbulent reynolds number. the length scale is the "height" of your first node away from the wall. the velocity scale is the friction velocity which is the square root of the (wall shear stress/ density). The y plus is used primarily to get a "feel" of where the log-region is in a turbulent boundary layer. This comes from the balance between production of tke and its dissipation rate. in fact, the shear stress is constant in this region, hence the log-law. In your case, if you wanna look at a "laminar y plus", i would use the length scale as the boundary layer height.

how can I plot Y plus for laminar flow in fluent?

run the case with a turbulence model and you will have that option. Otherwise if you choose the lamina model, you're basically doing a DNS. Here and you can just look at the wall shear stress to get a gauge of the yplus. yplus= friction velocity*y/kinematic viscosity. friction velocity =sqrt (wall shear stress/density).
You can use the User-defined scalars in fluent or define the formulation above in CFD post.

Avg. and local Nusselt number
 

Can anyone help me plz in calculating avg. and local nusselt numbers in fluent. I'm working on a heat transfer problem in fluent.....