For better understanding, few terms were introduced. These are non-dimensional numbers and represent respective properties of fluid or fluid flow.

These terms are known to be key parameters that govern the flow, and are best in guiding in presentation of experimental results and theoretical solutions.

While non-dimensioning the governing equations, some expressions together makeup a key term and “these” are some of the parameters.

Reynolds Number: ”The ratio of inertial forces to viscous forces within a fluid which is subjected to relative internal movement due to different fluid velocities”

Grashof Number: “The Grashof number is a dimensionless number in fluid dynamics and heat transfer which approximates the ratio of the buoyancy to viscous force acting on a fluid. It frequently arises in the study of situations involving natural convection and is analogous to the Reynolds number.”

Prandtl Number: “Prandtl number (Pr) is defined as the ratio of momentum diffusivity (kinematic viscosity) to thermal diffusivity”

Note: Prandtl number is something special, it doesn’t depend on fluid flow, but only on fluid properties.

**Eckert Number: *“*It expresses the relationship between a flow's kinetic energy and the boundary layer enthalpy difference, and is used to characterize heat transfer dissipation”

Nusselt Number: “The Nusselt number is the ratio of convective to conductive heat transfer across a boundary”