Experimental study on the instability and transition of the natural convection boundary layer

The instability and transition process of the natural-convection boundary layer around a vertical heated isothermal flat plate was investigated experimentally. It demonstrates that the characteristics of the unstable wave, measured at the flexion point in the velocity profile, consist with the results of linear stability theory. After an initial growth of its low frequency components, the comparatively higher frequency components develop and become to be turbulentized subsequently with a buoyancy subrange in its power spectra. In the inner sublayer, a new disturbance signal and its subharmonics in a much higher frequency domain were discovered near the wall and an inertial subrange was observed by its high frequency side in the spectra at Gr approximately equals 378.6.EI03340-3453