Convection From a Periodically Stretching Plane Wall

This paper documents the convection heat transfer enhancement effect that is associated with the periodic (timewise and spatial) longitudinal stretching of an infinite plane wall bathed by a semi-infinite fluid reservoir. It is shown that the flow field reaches a truly periodic state, and that the temperature field does not. The timedependent heat transfer rate is greater than the classical pure-diffusion limit only when the Reynolds number based on wall speed and wavelength is greater than 1. The enhancement effect becomes pronounced as Re increases above 10. The enhancement effect increases also as the Prandtl number increases, provided Re is greater than 1. The same conclusions apply in the case of convective mass transfer, when a concentration difference is maintained between the flexible wall and the ambient fluid.