Nusselt number

A dimension-less parameter characterizing the intensity of convective heat exchange between the surface of a body and the flow of a gas (fluid): , where is the coefficient of heat exchange, is the amount of heat radiated (or received) by the surface of the body in unit time, is the difference between the temperature of the surface of the body and that of the gas (fluid) outside the boundary layer, is the area of the surface, is the characteristic length, and is the coefficient of heat conductivity of the gas (fluid).

It is named after W. Nusselt.

References

[a1]	E.U. Condon, "Heat transfer" E.U. Condon (ed.) H. Odishaw (ed.) , Handbook of Physics , McGraw-Hill (1967) pp. §5.5.7–5.5.8
[a2]	E.R.G. Eckert, "Introduction to the transfer of heat and mass" , McGraw-Hill (1950)