Puff-slug transitions in a three-trophic-state model of transitional turbulence

Near the onset of turbulence in pipe flow, turbulence appears as localized patches. At lower Reynolds numbers these are puffs, which can decay or split; the puff-splitting regime is well described by directed percolation. At higher Reynolds numbers puffs give way to slugs, turbulent regions whose fronts move apart so that turbulence keeps invading the laminar flow.

This project asks what controls the transition from puffs to slugs. We study it in stochastic predator–prey models of transitional turbulence, centred on the three-trophic-state model proposed by Xueying Wang, in which turbulent activity feeds on the energy carried by the laminar shear flow.