The free convection heat transfer is significantly affected by

Explanation:

In convection studies, it is common practice to nondimensional the governing equations and combines the variables which group together into dimensionless numbers in order to reduce the number of total variables.

Nusselt number is a parameter to non-dimensional heat transfer coefficient.

Non-dimensional groupings

• Nusselt No. Nu = hLc/k = (convection heat transfer strength)/ (conduction heat transfer strength)
• Prandtl No. Pr = n/a = (momentum diffusivity)/ (thermal diffusivity)
• Reynolds No. Re = Ux/ν = (inertia force)/ (viscous force)

The dimensionless parameter which represents the natural convection effects and is called the Grashof number.

Grashof number, Gr, as the ratio between the buoyancy force and the viscous force:

\(Gr = \frac{{g\beta \left( {{T_s} - {T_\infty }} \right)L_c^3}}{{{\nu ^2}}}\)

Nusselt number is a function of the Grashof number and the Prandtl number alone. Nu = f (Gr, Pr)