What is turbulence?Revolution will not be televised |
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Comment: “I am a turbulence expert. This is not turbulence.” Response: You are correct - Re is low, in the transitional regime, and there is no inertial range in the Kolmogorov sense. Reynolds himself called this "sinuous motion" of a fluid. However, a wall-bounded flow explores a wide range of Re, from the laminar at the wall itself, through the boundary layer, to large scale motions further away from the wall. A precise dynamical description of unstable coherent structures observed close to the wall in all kinds of wall-bounded flows is an important piece of the overall puzzle of turbulence. The state space visualization described here is novel, and might be a useful tool for a fluid dynamics DNS expert. The idea: Pick a few typical coherent structures observed in your turbulent flow simulation, and use these to construct a low-dimensional state-space projection from your extremely high-dimensional data set. The tutorial develops the theory behind this state space representation in a sequence of gentle steps. |