Small scale velocity jumps in shear turbulence

Area of Science:

• Fluid dynamics
• Turbulence research
• Statistical mechanics

Background:

• Understanding turbulence is crucial for many scientific and engineering fields.
• Sheared turbulence presents unique challenges due to anisotropic energy transfer.
• Previous studies have explored turbulence structures, but detailed analysis in sheared flows is ongoing.

Purpose of the Study:

• To investigate structure functions and turbulence structures in uniformly sheared strong turbulence.
• To determine the scale-to-scale energy transfer and persistence of large-scale shear.
• To analyze the asymmetry in velocity increments and identify signatures of small-scale structures.

Main Methods:

• Utilized an array of hot-wire velocity sensors for precise measurements.
• Analyzed structure functions and spatial velocity gradients.
• Examined velocity increments in both shear and perpendicular directions.

Main Results:

• Confirmed the persistence of large-scale shear down to the smallest turbulent scales.
• Observed a significant asymmetry between velocity increments in the shear direction and perpendicular to it.
• Identified scaling exponents tending to a constant in the shear direction, indicative of small-scale cliffs.

Conclusions:

• The findings demonstrate the enduring influence of large-scale shear on small-scale turbulence dynamics.
• The observed asymmetry and small-scale cliffs provide new insights into the anisotropic nature of sheared turbulence.
• This research offers valuable data for refining turbulence models and theories.