Major research outcome
- Master’s Graduate Donghyun Lee and Professor Sang Lee Identify the Mechanism for Simultaneous Reduction of Wall Pressure Fluctuations and Skin-Friction Drag in Turbulent Boundary Layers via Streamwise-Traveling Wall Oscillations
- 관리자 |
- 2026-05-04 20:59:30|
- 48
- 2026-05-04 20:59:30|
Wall pressure fluctuations and skin-friction drag generated in turbulent boundary layers are major sources of aerodynamic noise, structural vibration, and energy loss. This study investigates active near-wall flow control mechanisms for simultaneously reducing pressure fluctuations and skin-friction drag in a high-Reynolds-number, zero-pressure-gradient turbulent boundary layer.
Master’s graduate Donghyun Lee and Professor Sang Lee performed high-resolution direct numerical simulations (DNS) to compare an uncontrolled baseline with four active flow control strategies: uniform blowing, uniform suction, spanwise wall oscillation (SWO), and streamwise-traveling wave with wall oscillation (STWO). The study quantitatively assessed how each control method modifies near-wall vortical structures by analyzing vorticity, enstrophy, wall pressure fluctuations, premultiplied energy spectra, and correlations between wall pressure fluctuations and streamwise vorticity.
The results showed that uniform blowing reduced the skin-friction coefficient by approximately 25%, but increased the peak energy of the wall pressure fluctuation spectrum by about 19%. In contrast, uniform suction reduced the pressure fluctuation energy by approximately 20–25%, but increased the skin-friction coefficient by up to 34%, revealing a clear trade-off between pressure fluctuation suppression and drag reduction. SWO and STWO, however, achieved simultaneous reductions in both skin-friction drag and wall pressure fluctuations. In particular, STWO showed the best overall performance, reducing the skin-friction coefficient by approximately 33% and decreasing wall pressure fluctuation energy by about 40% in the region of 10 & y⁺ & 100.
The study further demonstrated that these reductions are closely associated with the weakening of quasi-streamwise vortices and low-speed streak structures, the reduction of spanwise enstrophy, and the decreased correlation between wall pressure fluctuations and streamwise vorticity. These findings confirm that STWO effectively disrupts the near-wall turbulence regeneration mechanism and serves as a promising active flow control strategy for simultaneously suppressing pressure fluctuations and skin-friction drag.
This study was published online in September 2025 in Physics of Fluids, a leading international journal in fluid dynamics.
https://doi.org/10.1063/5.0281564
Master’s graduate Donghyun Lee and Professor Sang Lee performed high-resolution direct numerical simulations (DNS) to compare an uncontrolled baseline with four active flow control strategies: uniform blowing, uniform suction, spanwise wall oscillation (SWO), and streamwise-traveling wave with wall oscillation (STWO). The study quantitatively assessed how each control method modifies near-wall vortical structures by analyzing vorticity, enstrophy, wall pressure fluctuations, premultiplied energy spectra, and correlations between wall pressure fluctuations and streamwise vorticity.
The results showed that uniform blowing reduced the skin-friction coefficient by approximately 25%, but increased the peak energy of the wall pressure fluctuation spectrum by about 19%. In contrast, uniform suction reduced the pressure fluctuation energy by approximately 20–25%, but increased the skin-friction coefficient by up to 34%, revealing a clear trade-off between pressure fluctuation suppression and drag reduction. SWO and STWO, however, achieved simultaneous reductions in both skin-friction drag and wall pressure fluctuations. In particular, STWO showed the best overall performance, reducing the skin-friction coefficient by approximately 33% and decreasing wall pressure fluctuation energy by about 40% in the region of 10 & y⁺ & 100.
The study further demonstrated that these reductions are closely associated with the weakening of quasi-streamwise vortices and low-speed streak structures, the reduction of spanwise enstrophy, and the decreased correlation between wall pressure fluctuations and streamwise vorticity. These findings confirm that STWO effectively disrupts the near-wall turbulence regeneration mechanism and serves as a promising active flow control strategy for simultaneously suppressing pressure fluctuations and skin-friction drag.
This study was published online in September 2025 in Physics of Fluids, a leading international journal in fluid dynamics.
https://doi.org/10.1063/5.0281564
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