An excursion into ecology and two sets of experiments lay the foundation for our Focus on Turbulence.
Decades-old speculation that the transition to turbulence belongs to the directed percolation universality class is confirmed with theoretical, numerical and experimental evidence in our Focus on Turbulence.
For a problem as complex as turbulence, combining universal concepts from statistical physics with ideas from fluid mechanics has proven indispensable. Three decades since this link was formed, it is still providing food for new thought.
In the transition from laminar to turbulent pipe flow, puffs of turbulence form, split and decay. The phenomenology and lifetime of these turbulent puffs exhibit population dynamics that also drive predator–prey ecosystems on the edge of extinction.
Simulated pipe flow is interpreted using an ecological model in which predatory zonal flow preys on turbulence, and laminar flows emulate nutrients — establishing a link between turbulence and the directed percolation universality class.
Experiments and simulations of the transition to turbulence in fluid flow through a quasi-2D channel reveal critical exponents consistent with directed percolation — long conjectured to be the universality class associated with the transition.
Decades-old speculation that the transition to turbulence belongs to the directed percolation universality class is confirmed with experimental and numerical data for flow through a quasi-one-dimensional Couette geometry.