Left panel: vertical profile of (solid line) and (dashed line), time averaged between t = 400 and t = 600 and radially averaged between R = 3 and R = 6. The two stresses are similar both in amplitude and in their vertical profile. Right panel: vertical profile of (solid line) and (dashed line), time averaged between t = 400 and t = 600 and radially averaged between R = 3 and R = 6. Although they are comparable in magnitude, the viscous and turbulent stresses display largely different vertical profiles.