A numerical study on the natural transition locations in the flat-plate boundary layers on superhydrophobic surfaces
A numerical study on the natural transition locations in the flat-plate boundary layers on superhydrophobic surfaces
复制标题
超疏水表面平板边界层自然过渡位置的数值研究
DOI：
10.1063/5.0030713
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发表时间：
2020-12
影响因子：
4.6
通讯作者：
Yongming Zhang
中科院分区：
文献类型：
--
作者：
Bin Liu;Yongming Zhang
本文用数值方法研究了超疏水表面平板边界层的自然过渡位置。通过求解具有壁面滑速边界条件的Blasius方程，得到了整个流方向计算域中的层流场。超疏水表面的边界层比普通表面的边界层变薄。对层流边界层进行了线性失稳分析，并采用eN方法预测了过渡位置。超疏水表面上的二维（2D） Tollmien-Schlichting （T-S）波仍然比三维（3D）波更不稳定，因此仅考虑二维波来预测过渡。随着滑移长度的增加，流动失稳的临界位置向下游移动，不稳定区域变小。因此，超疏水表面具有延迟自然转变的作用，并且随着滑移长度的增加，延迟效应越强。迎面流速度越大，不稳定T-S波频率越高，不稳定区越大。随着迎面而来流速的增大，超疏水表面上的过渡位置先向上游移动，然后向下游移动。因此，在最靠近前缘的过渡位置对应一个“危险”迎面而来的流速。此外，超疏水表面的过渡延迟效应随着迎面流速度的增加而增强。
In this paper, the natural transition locations in the flat-plate boundary layers on the superhydrophobic surfaces are studied by numerical methods. The laminar flow field in the whole stream-wise computational domain is obtained by solving the Blasius equation with the slipvelocity boundary condition on the wall. The boundary layer on the superhydrophobic surface becomes thinner than that on the ordinary surface. The linear instability analysis is performed on the laminar boundary layer, and the eN method is employed to predict the transition location. The two-dimensional (2D) Tollmien–Schlichting (T–S) waves are still more unstable than the three-dimensional (3D) ones on the superhydrophobic surfaces, so only the 2D waves are taken into consideration to predict transition. As the slip length becomes longer, the critical location of flow instability moves further downstream, and the unstable zone becomes smaller. Therefore, the superhydrophobic surfaces have the effect of delaying the natural transition and that the delay effect becomes stronger as the slip length becomes longer. The higher oncoming flow velocity leads to higher frequencies of the unstable T–S waves and the larger unstable zone. As the oncoming flow velocity rises, the transition location on the superhydrophobic surface moves once upstream and then downstream. Consequently, there is a “dangerous” oncoming flow velocity corresponding to the transition location, which is the closest to the lead edge. Furthermore, the transition delay effect of the superhydrophobic surface becomes stronger with the increase in the oncoming flow velocity.
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影响因子：
4.6
作者：
Choi, CH;Westin, KJA;Breuer, KS
通讯作者：
Breuer, KS
影响因子：
4.6
作者：
W. Rowin;J. Hou;S. Ghaemi
通讯作者：
W. Rowin;J. Hou;S. Ghaemi
DOI：
--
发表时间：
1956
期刊：
--
影响因子：
--
作者：
J. V. Ingen
通讯作者：
J. V. Ingen
影响因子：
9.9
作者：
CHURAEV, NV;SOBOLEV, VD;SOMOV, AN
通讯作者：
SOMOV, AN
影响因子：
0.8
作者：
A. K. Chu
通讯作者：
A. K. Chu