Flow instability in roll cell convection

Overview

If low-temperature fluid flows on a level heating plate, an unstable stratification by the density difference will be formed. At this time, longitudinal vortices (roll-cell convection) occur depending on a buoyancy parameter. Although the critical parameter has been found by many linear stability theories, there is a big gap. Since the determination of the onset point is not unified, comparison between theory and experiment are not enough. By this research, longitudinal vortices are generated by a heated plate in a wind tunnel. We measure the direction multipoint of span simultaneous temperature using the thermocouple array which put many thermocouples in order, and it is investigating about average form, the rms value of fluctuation, the unsteady action of longitudinal vortices, etc. By numerical calculation, growth of longitudinal vortices and the span wise movement were clarified by DNS. By experiment, generating of longitudinal vortices was found by visualization and temperature measurement. Now, in order to investigate the growth process of longitudinal vortices, mainstream velocity and difference of temperature are changed and measure the temperature distribution in detail. Research is advanced in order to determine theoretically a critical parameter simultaneously using linear stability theory.