Stratification effect on extreme-scale rolls in plane Couette flows

The effect of weak stratification on turbulent plane Couette flows is studied by means direct numerical simulations at the Prandtl number air. We demonstrate that tends to reduce intensity streamwise streaks in channel center, eventually breaking characteristic large-scale rolls. By analyzing bursting mechanism (i.e. sweeps and ejections) responsible for vertical momentum transfer, we observe weaker events a disorganized spatial configuration. This scenario no longer supports generation rolls center.