Wave dispersion in moderate channel turbulence

Area of Science:

• Fluid Dynamics
• Turbulence Theory
• Wave Phenomena

Background:

• Traditional turbulence models often assume "frozen eddies," where turbulent structures remain unchanged as they move.
• This assumption, known as Taylor's hypothesis, breaks down in non-weak turbulence.
• Understanding the dynamic evolution of turbulent structures is crucial for accurate flow prediction.

Purpose of the Study:

• To investigate the wave-like properties of turbulent vorticity.
• To apply stochastic methods from oceanic field analysis to channel turbulence.
• To explore the breakdown of Taylor's hypothesis in turbulent flows.

Main Methods:

• Interpreting turbulent vorticity as analogous to ocean wave packets.
• Utilizing stochastic methods for analyzing oceanic fields.
• Analyzing turbulent flow data at a bulk Reynolds number (Re _b ) of 5600.

Main Results:

• Vortical packets in channel turbulence exhibit ocean-like behavior.
• Turbulent structures change shape and speed as they are advected, indicating wave dispersion.
• Turbulent fluctuations display dispersive characteristics similar to gravity-capillary waves.

Conclusions:

• Turbulence possesses inherent dispersive properties, akin to wave phenomena.
• Capillarity plays a dominant role in the dispersive behavior of turbulence near wall regions.
• The findings suggest a paradigm shift in understanding turbulence beyond the "frozen eddy" concept.