Abstract
Direct numerical simulations of streamwise-localized turbulent flow(turbulent puff) in a horizontal square duct heated from above are performed at Richardson numbers 0≦R_i≦0.25 to characterize differences between isothermal and non-isothermal puffs.It is found that the structure of the non-isothermal puff exhibits significantlly different properties from that of the isothermal puff.In particular,differences are observed in wall shear stresses.In the upstream part of the non-isothermal puff higher shear appears on the horizontal walls than the vertical ones.The higher shear on the horizontal walls in the upstream part is interpreted in terms of coherent streamwise vortices induced by buoyancy in the corner regions.
