Opposition control (OC), which suppresses drag-inducing motions near the wall by local blowing and suction, has been shown to be effective in reducing drag in wall-bounded turbulence at low Reynolds numbers ($\text{Re}$). However, its performance at high $\text{Re}$ remains an open question. Here we investigate OC at high $\text{Re}$ using direct numerical simulations of turbulent channel flow at friction Reynolds numbers (${\text{Re}}_{\tau }$) ranging from 200 to 2000, delineating its limitations and identifying the physical mechanisms responsible. The principal finding is that drag reduction ($\mathcal{DR}$) decreases with increasing ${\text{Re}}_{\tau }$, consistent with similar low $\text{Re}$ results reported in the literature. For the detection plane at $y_d^{+}=15, \mathcal{DR}$ decreases from $22.3\%$ at ${\text{Re}}_{\tau }=200$ to $18.1\%$ at ${\text{Re}}_{\tau }=2000$. In addition, the optimal $y_d^{+}$ moves slightly inward as ${\text{Re}}_{\tau }$ increases, in line with the inward shift of the near-wall peak of the streamwise vorticity fluctuation. Using previously proposed models, we predict that an approximately $15\%$ drag reduction can be obtained at high Reynolds numbers, say, ${\text{Re}}_{\tau }\ge {10}^4$. Interestingly, the root-mean-square wall-normal velocity fluctuation at the wall ($v_{\mathrm{rms},w}^{\prime +}$) to achieve the maximum $\mathcal{DR}$ is around 0.25 for all ${\text{Re}}_{\tau }$ cases. Further statistical analysis reveals that the decrease in $\mathcal{DR}$ at high ${\text{Re}}_{\tau }$ is due to a reduced ability to suppress large-scale turbulence near the wall, whose contribution continuously increases due to the enhanced modulation and penetration effect of the outer large-scale and very large-scale motions. Coherent structure analysis confirms the inability of OC to control outer large-scale structures and shows the strengthening of near-wall streamwise vortices with increasing ${\text{Re}}_{\tau }$. These findings suggest that future efforts should explore advanced approaches such as hybrid control strategies incorporating phase-lag formulations or complementary actuation targeting outer-layer motions, to extend the effectiveness of OC at high $\text{Re}$.

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• Boundary layers
• Drag reduction
• Turbulence