Nusselt Number
Nusselt number
[′nu̇s·əlt ‚nəm·bər]Nusselt Number
a dimensionless parameter that characterizes the intensity of convective heat exchange between the surface of a body and a flow of gas (or liquid). It is named after the German physicist W. Nusselt (1882–1957). The Nusselt number Nu = αl/λ, where α = Q/(S · ΔT) is the heat-exchange coefficient, Q is the heat transfer across the surface of the body per unit time, ΔT > O is the difference of temperature between the surface of the body and the gas (or liquid) measured outside the boundary layer, S is the area of the surface, l is a characteristic dimension, and λ is the coefficient of thermal conductivity of the gas.