What is external flow?
In fluid mechanics, external flow is such a flow that boundary layers develop freely, without constraints imposed by adjacent surfaces. Accordingly, there will always exist a region of the flow outside the boundary layer in which velocity, temperature, and/or concentration gradients are negligible. It can be defined as the flow of a fluid around a body that is completely submerged in it.
An example includes fluid motion over a flat plate (inclined or parallel to the free stream velocity) and flow over curved surfaces such as a sphere, cylinder, airfoil, or turbine blade, air flowing around an airplane and water flowing around the submarines.
How to Calculate Nusselt number?
Nusselt number calculator uses Nusselt Number = 0.37*Reynolds Number^0.6 to calculate the Nusselt Number, Nusselt number formula is defined as a dimensionless value that characterizes convective heat transfer between a sphere and a fluid, providing a measure of the ratio of convective to conductive heat transfer across the boundary layer surrounding the sphere. Nusselt Number is denoted by Nu symbol.
How to calculate Nusselt number using this online calculator? To use this online calculator for Nusselt number, enter Reynolds Number (Re) and hit the calculate button. Here is how the Nusselt number calculation can be explained with given input values -> 244.109 = 0.37*50000^0.6.