A PIV measurement of the natural transition of a natural convection boundary layer

作者：Zhao Yongling^*; Lei Chengwang; Patterson John C

来源：Experiments in Fluids, 2015, 56(1): 9.

DOI：10.1007/s00348-014-1891-5

A natural convection boundary layer undergoing natural transition to turbulence is investigated by particle image velocimetry (PIV) measurements for the first time. The boundary layer adjacent to an isothermally heated plate immersed in water is subjected to environmental noise, the transition of which is therefore regarded as a natural transition. Distinct stripe-like flow structures characterising the natural transition of the natural convection boundary layer are visualised for the first time by the PIV experiments. The spatial wavenumber and the frequency of the flow structures are further quantified by applying a two-dimensional Fourier transform to time series of the flow properties. A distinct transitional regime in the boundary layer is noted, in which the three-dimensionality of the flow grows exponentially in the streamwise direction. The characteristic frequency of the natural convection boundary layer is also obtained from the PIV measurements, which agrees well with a theoretical prediction reported previously.

• 出版日期2015-1