PIV Measurements of the Spanwise Flow Characteristics in a Naturally Transitioning Natural Convection Boundary Layer
Yongling Zhao, Chengwang Lei, John C. Patterson · 2014
This paper presents particle image velocimetry (PIV) measurements of the spanwise flow characteristics in a natural convection boundary layer undergoing natural transition (i.e. induced by stochastic environmental disturbances). The boundary layer measured in the present experiment is formed adjacent to an isothermally heated plate immersed in water. The transition of the boundary layer from a transitional flow to a threedimensional flow is visualised from the streamwise development of the spanwise flow structures. The frequencies and spatial wavenumbers of the spanwise flow structures at various streamwise positions are quantified by applying a twodimensional Fourier transform to the time series of the spanwise velocity components measured along the spanwise direction. It is also understood that during the natural transition, spanwise flow structures appear in the boundary layer, which present a distinct frequency and a spatial wavenumber.