On the possible existence of a co-supporting cycle of large-scale and near-wall structures in wall turbulence

Direct numerical simulation of a turbulent channel flow in a periodic domain of relatively wide spanwise extent, but minimal streamwise length, is carried out at Reynolds number R.e(tau) = 349. The large-scale structures previously observed in studies of turbulent channel flow using huge computational domains are also shown to exist even in the streamwise-minimal channel of the present work. In the system, it is also clearly observed how the large-scale structures and the near-wall structures affect each other. While the collective behaviour of near-wall structures enhances a large-scale structure, the resulting large-scale structure in turn activates the generation and drift of the latter. Hence near-wall and large-scale structures interact in a co-supporting cycle.