This paper describes an experimental investigation, supported by analysis, of free convection in an air-water vapor boundary layer at the stagnation point of a horizontal cylinder. A two-component boundary layer is created by the effusion of water vapor from the porous surface of the cylinder; the ambient gas is pure air. The results of both experiment and analysis indicate that the heat transfer decreases as the surface mass-transfer rate increases. At moderate blowing rates, there is good agreement between the experimentally- and analytically-determined Nusselt numbers. At higher mass-transfer rates, the data lie above the analytical predictions by about 25 per cent. This departure is attributed to a fluctuating motion in the boundary layer.
Bibliographical noteFunding Information:
The research described herein was supported by a grant from the U.S. Air Force Office of Scientific Research, Mechanics Division. The authors are indebted to Professor E. R. G. Eckert for incisive discussion,a nd to Mr. W. J. Minkowycz for assistancew ith the computer operations.