Nusselt number

The Nusselt number is a dimensionless measurement used in heat transfer studies to compare how efficiently heat is moved within a fluid (like air or water) to how it would be transferred by simple conduction alone. A higher Nusselt number indicates that convection—the movement of the fluid—is significantly enhancing heat transfer, beyond just conduction. It helps engineers understand and predict heat flow in systems like cooling devices and heat exchangers, by showing the relative importance of fluid motion in transferring heat in different situations.