Abstract The wall suction & slip effect of the bionic metasurface with periodic spherical grooves on the vehicle body surface is proposed for aerodynamic noise control, and physical mechanism is investigated by theoretical analysis and simulation. When fluid flows through the grooved vehicle body surface, wall suction effect occurs due to clockwise pressure difference around the interior groove. The trailing vortex region of the vehicle body is reduced, the fluctuating pressure on the wall surface decreases, and the adverse pressure in the boundary layer is relieved. On the other hand, a slip velocity consistent with flow direction is generated at the interface corresponding to grooves, which results in reduced velocity gradient in the boundary layer and decreased thickness of the boundary layer. Ideally, the boundary layer could disappear when the velocity of slippage is increased to that of the flow by adjusting the grooves parameters, such as, the groove depth, pitch, and radius. Overall, the wall suction & slip effect fundamentally prevents generation of the boundary layer and delays its separation. Finally, effective control of aerodynamic noise within 450–1000 Hz on the vehicle body surface is realized by an average drop of 11.97 dB and up to 100% at 500 Hz. This study opens up a possibility for full control of boundary layer and could have effective applications in controlling aerodynamic noise.

中文翻译：

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球形凹槽仿生超表面的壁吸和滑移效应控制气动噪声

摘要 提出了车身表面具有周期性球形凹槽的仿生超曲面的壁吸滑移效应用于气动噪声控制，并通过理论分析和仿真研究了物理机制。当流体流过带槽的车身表面时，由于内部槽周围的顺时针压力差而产生壁吸力。车身尾涡区域减小，壁面脉动压力减小，边界层内的逆压力得到缓解。另一方面，凹槽对应的界面处会产生与流向一致的滑移速度，导致边界层速度梯度减小，边界层厚度减小。理想情况下，当滑动速度增加到流动速度时，通过调整凹槽参数，如凹槽深度、节距和半径，边界层可能会消失。总体而言，壁面吸滑效应从根本上阻止了边界层的产生并延迟了其分离。最后，通过平均下降 11.97 dB 和 500 Hz 时高达 100% 的方式，实现了对车身表面 450-1000 Hz 范围内空气动力噪声的有效控制。这项研究开辟了完全控制边界层的可能性，并在控制气动噪声方面具有有效的应用。滑移效应从根本上阻止了边界层的产生并延迟了其分离。最后，通过平均下降 11.97 dB 和 500 Hz 时高达 100% 的方式，实现了对车身表面 450-1000 Hz 范围内空气动力噪声的有效控制。这项研究开辟了完全控制边界层的可能性，并在控制气动噪声方面具有有效的应用。滑移效应从根本上阻止了边界层的产生并延迟了其分离。最后，通过平均下降 11.97 dB 和 500 Hz 时高达 100% 的方式，实现了对车身表面 450-1000 Hz 范围内空气动力噪声的有效控制。这项研究开辟了完全控制边界层的可能性，并在控制气动噪声方面具有有效的应用。