The gas–liquid interface (GLI) over superhydrophobic surfaces (SHSs), where the flow slips, is the key to reduce frictional drag in underwater applications. Many-body dissipative particle dynamics simulations are used to explore the slip behavior of a shear flow over a rectangular grooved SHS, and a flat GLI is obtained by tuning the contact angle of the GLI. Due to the slip, the normal profiles of the local velocity, which are perpendicular to the GLI, are curved and shifted away from the linear form near the GLI. Then, a polynomial function is proposed to fit the velocity profile to extract the local shear rate and calculate the slip length. Based on this fitting method, a hybrid slip boundary condition is derived for both longitudinal and transverse flows. That is, the shear stress and slip length are finite near the groove edge, and the stress is nearly zero and the slip length is infinite in the center region of the GLI. This new hybrid slip boundary condition not only explains the inconsistent slip conditions reported in the literature under different groove length scales, but also unifies the existing exclusive slip assumptions.

中文翻译：

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超疏水表面局部滑移的多体耗散粒子动力学研究

超疏水表面 (SHS) 上的气液界面 (GLI) 是流动滑动的地方，是减少水下应用中摩擦阻力的关键。多体耗散粒子动力学模拟用于探索剪切流在矩形槽 SHS 上的滑移行为，并通过调整 GLI 的接触角获得平坦的 GLI。由于滑移，垂直于 GLI 的局部速度的法向剖面弯曲并偏离 GLI 附近的线性形式。然后，提出多项式函数来拟合速度剖面以提取局部剪切速率并计算滑移长度。基于这种拟合方法，推导出纵向和横向流动的混合滑动边界条件。也就是说，切应力和滑移长度在凹槽边缘附近是有限的，在 GLI 的中心区域，应力几乎为零，滑移长度无穷大。这种新的混合滑动边界条件不仅解释了文献中报告的不同凹槽长度尺度下不一致的滑动条件，而且统一了现有的专属滑动假设。