疏水表面滑移流动及减阻特性的格子Boltzmann方法模拟
Lattice Boltzmann simulation of slip flow and drag reduction characteristics of hydrophobic surfaces
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摘要: 采用格子Boltzmann方法研究了固体壁面对流体的作用强度与其润湿性的关系,在此基础上进一步模拟了疏水表面微通道内的流体流动,获得了润湿性对疏水表面滑移流动及减阻特性的影响规律,证实了疏水表面表观滑移的存在性并揭示了其产生机理。结果表明,疏水性作用在疏水表面的近壁区诱导了一个低密度层,而表观滑移则发生在低密度层上。表观滑移是疏水表面具有减阻作用的直接原因,减阻效果随滑移长度的增大而增大。对于特定的流体系统,滑移长度是疏水表面的固有属性,仅是壁面润湿性的单一函数,而与流动本身的性质无关。
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关键词:
- 疏水表面 /
- 滑移流动 /
- 减阻机理 /
- 格子Boltzmann方法
Abstract: The relationship between the surface wettability and the interaction strength of liquid-wall particles is first in-vestigated using a lattice Boltzmann method, and then the liquid flow over hydrophobic surfaces is simulated in a microchannel. Effect of surface wettability on the slip flow and drag reduction characteristics of hydrophobic surfaces is obtained. Existence of the apparent slip on hydrophobic surfaces is confirmed and its mechanism is revealed. Simulation results show that the hydrophobicity induces a low density layer near the wall of hydrophobic surfaces and the apparent slip is observed on the low density layer. It is shown that the apparent slip is a direct cause of hydrophobic surfaces’ drag reduction effect. Thus the drag reduction effect increases with increasing slip length. For a specific fluid system, the slip length is an inherent property of the hydrophobic surfaces and is a single function of the surface wettability. The slip length does not change with the external flow property. -
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