AI 中文总结
本研究用3D-PTV测量雷诺应力张量谱输运，验证了实验框架，首次分解ZPG TBL的非线性输运项，探究壁面强迫减阻对能量转移的影响，为减阻流动研究提供实验依据。
AI 中文摘要
采用三维粒子追踪测速（3D-PTV）测量来计算雷诺应力张量的谱输运。在摩擦雷诺数$Re_\tau = 1020$的零压力梯度（ZPG）湍流边界层（TBL）中验证了该实验框架，证明其能充分解析主导的非线性能量转移机制，以得出基于流动物理的结论。针对ZPG TBL的流向雷诺应力，首次对非线性输运项进行分量分解，揭示了与展向和法向对流相关的不同能量转移机制。将同一实验框架应用于减阻（约38%）的TBL流动，该流动通过施加稳定的流向交替展向壁面速度实现。此壁面强迫导致非线性能量转移强烈衰减并向远离壁面的方向偏移，能量转移机制在定性上仍与典型ZPG TBL相似，表明现有机制仅需调整以适应新的低湍动能态。
英文摘要
Three-dimensional particle-tracking velocimetry (3D-PTV) measurements were used to compute the spectral transport of the Reynolds-stress tensor. The experimental framework is validated for a zero-pressure-gradient (ZPG) turbulent boundary layer (TBL) at a friction Reynolds number $Re_τ= 1020$, demonstrating that the dominant non-linear energy transfer mechanisms are adequately resolved to draw flow physics-based conclusions. For the streamwise Reynolds stress in the ZPG TBL, a component-wise decomposition of the non-linear transport term is considered for the first time, which reveals distinct energy transfer mechanisms associated with the spanwise and wall-normal advection. The same experimental framework was applied to a drag-reduced ($\approx 38\%$) TBL flow, achieved by imposing a steady streamwise-alternating spanwise wall velocity. This wall forcing causes a strong attenuation of non-linear energy transfer and its shift away from the wall. The energy transfer mechanisms remain qualitatively similar to those of the canonical ZPG TBL, suggesting that the existing mechanisms simply readjust to their new low-turbulent-energy state.
