$Nu_{D}=hD/k$
Heat conduction in a solid, liquid, or gas occurs due to the vibration of molecules and the transfer of energy from one molecule to another. In solids, heat conduction occurs due to the vibration of molecules and the movement of free electrons. In liquids and gases, heat conduction occurs due to the vibration of molecules and the movement of molecules themselves. $Nu_{D}=hD/k$ Heat conduction in a solid, liquid, or
The heat transfer due to convection is given by: $Nu_{D}=hD/k$ Heat conduction in a solid