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Acceleration is the key to drag reduction in turbulent flow
Liuyang Ding1, Lena F Sabidussi1, Brian C Holloway2
1Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544.
Summary
Surface oscillations in pipe flow can reduce drag by up to 35%. Researchers found that surface acceleration, not velocity or period, is the key factor, simplifying drag reduction strategies for turbulent flows.
Area of Science:
- Fluid dynamics
- Turbulence research
- Surface oscillation phenomena
Background:
- Turbulent pipe flow is energy-intensive due to frictional drag.
- Previous studies explored drag reduction using surface oscillations, with varying scaling parameters.
- Understanding drag reduction mechanisms is crucial for energy efficiency.
Purpose of the Study:
- To investigate drag reduction in turbulent pipe flow with azimuthal surface oscillations.
- To identify the primary scaling parameter governing drag reduction.
- To determine if findings apply to other geometries, like channel flows.
Main Methods:
- Experimental study of turbulent pipe flow.
- Azimuthal oscillation of the pipe surface across various frequencies, amplitudes, and Reynolds numbers.
- Analysis of drag reduction data to identify key parameters.
Main Results:
- Achieved drag reduction up to 35% through surface oscillation.
- Identified surface acceleration as the critical parameter, simplifying previous models.
- Confirmed the applicability of findings to channel flows with spanwise surface oscillation.
Conclusions:
- Surface acceleration is the unifying parameter for drag reduction in oscillating flows.
- This discovery offers a simplified approach to optimizing drag reduction.
- Potential applications include reducing fuel consumption and energy costs in large-scale systems.
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