Effect of Heating on Gortler Instability.

Experimental investigations of the effect of heating from below on the vortex instability in a laminar boundary layer flow of air along a concave surface are reported. The experiment covers the range of parameter Gr/G('2) between 0 and 8.5. The wavelength of the vortices remains unchanged with heating and the strength of the vortices is enhanced by heating. The amplitude of the vortices increases almost exponentially with the combined parameter (G('2) + fGr)(' 1/2), where f is found to be between 0.3 and 0.4, until the non-linear effects become important. As the value of Gr/G('2) is increased, the non-linear effects become noticeable at a smaller value of the parameter G('2) + fGr.