For determination of heat transfer coefficient for convective heat flow for any set of conditions use is made of experimental data and dimensionless numbers are developed. What are these numbers and how they can be interpreted physically ?

Nusselt number, Prandtl number, Grashof number, and Reynolds number.
Nusselt number is ratio of temperature gradient in the fluid immediately in contact with the surface to a reference temperature gradient.
Prandtl number is a ratio of the physical properties of the fluid.
Grashof number is ratio of buoyant to viscous forces in convective system.
Reynolds number is ratio of the fluid flo^v inertia forces to viscous forces.