Laminar-turbulent transitions at natural convection in flat and annular vertical fluid layers

The evolution of the local characteristics of natural convective boundary layers along the longitudinal coordinate is studied experimentally. The spatial forms of secondary flows in boundary layers on the walls of the plane and annular vertical liquid layer heated to different temperatures and in the core of the layers are studied. Hot walls are transparent, which allows video recording in two planes. In the regions of the laminar, transition, and turbulent boundary layer, local fields of velocity and temperature and local heat fluxes are measured.