Revisiting ‘bursts’ in wall-bounded turbulence

Since the advancements in technologies to measure turbulence, it has been widely observed that a turbulent signal exhibits high-intensity activities that last for a certain duration followed by quiet periods. In our day-to-day lives, we experience the presence of such high-intensity turbulent bursts when suddenly strong gusts appear in the winds or those unpleasant bumpy flights with vigorous shaking. Apart from its pragmatic appeal, on a fundamental level, the presence of bursts renders the efforts toward developing a universal approach to turbulence modeling difficult. Therefore, understanding these bursts is of both theoretical and practical interest to the turbulence community. Motivated by this need, we demonstrate that the problem of turbulent bursts can be tackled through a complex systems approach, an emerging research area that has its roots at the heart of statistical physics. Specifically, by considering both the duration and intensity of the bursting events, one can incorporate the effect of bursts on the turbulence statistics at any specified scale of the flow, allowing the authors to connect the origin of bursts to the presence of organized eddy motions in turbulent flows called ‘coherent structures’, thereby revealing a hidden aspect of universality associated with turbulent bursts. Accordingly, this study paves the way toward the development of next-generation models of turbulent flows, by creating a union between complex systems science and fluid mechanics.