Turbulence is often treated as memoryless. Once the forcing and control parameters are fixed and after any transients have decayed, the system settles into a unique, statistically stable turbulent state. A growing body of work shows that this paradigm does not have to be true. Even under identical forcing and boundary conditions, turbulent flows may sustain multiple long-lived structures, each with its own characteristic transport properties and fluctuations. The paper by Yao et al. (2026 J. Fluid Mech. , vol. 1030, R4) demonstrates this phenomenon particularly clearly for centrifugal convection, where the flow self-organises into different numbers of coherent rolls depending on the initial conditions. Beyond reporting the observation of multiple flow states, they provide a theoretical explanation as to why only certain flow states can exist and why the range of possible multiple states shrinks as turbulence intensifies.
Heng-Dong Xi (Tue,) studied this question.