Dissipative Effects on Inertial-Range Statistics at High Reynolds Numbers

Area of Science:

• Fluid Dynamics
• Turbulence Research
• Experimental Physics

Background:

• Classical grid turbulence is a fundamental research area in fluid dynamics.
• Understanding the inertial range of turbulence is crucial for developing accurate predictive models.
• Existing models often assume local energy transfer and limited influence of dissipation on larger scales.

Purpose of the Study:

• To experimentally investigate velocity structure functions in classical grid turbulence.
• To identify and characterize oscillations within the inertial range of turbulent flows.
• To assess the influence of dissipation on inertial-range statistics at high Reynolds numbers.

Main Methods:

• Utilizing the Variable Density Turbulence Tunnel for controlled experiments.
• Acquiring extremely long time series data (up to 10^10 samples) of turbulent velocity.
• Employing both hot-wire probes and nanoscale thermal anemometry probes.
• Conducting measurements across a wide range of high Reynolds numbers (R_λ=110 to 1600).

Main Results:

• Observed novel oscillations in velocity structure functions within the inertial range.
• Collected data spanning O(10^7) integral length scales.
• Confirmed findings with multiple measurement techniques.

Conclusions:

• The experimental results indicate that dissipation influences inertial-range statistics at unexpectedly large scales.
• Current turbulence models may underestimate the range of dissipation's influence.
• These findings necessitate a re-evaluation of theoretical frameworks for turbulent flows.