流体中微量的水溶性聚合物添加剂可抑制湍流并大幅降低摩擦阻力，是流动控制与减阻的重要手段，然而高分子链易在高剪切率湍流环境中剪断而失效或降低性能，限制其应用范围；超疏水材料在水流过时可在其表面产生有效滑移，在流动减阻、表面防污等领域具有十分广阔的应用前景，而高压强、高扩散流动环境严重影响其表面气体的长存性而使其失效。因此，本项目拟结合二者的流动特性，添加聚合物抑制超疏水材料表面气体的湍流扩散，并降低其湍流压力的峰值；另一方面利用超疏水表面的有效滑移，降低最大剪切率；从而在协同工作中增加二者的失效阈值。项目拟通过数值模拟，研究二者对减阻的竞争性机理、最大减阻量和减阻适用性。随后将依据超疏水材料表面的真实物理特性，结合水平集与浸入边界法开发考虑表面张力和微结构变形下的数值计算程序，研究超疏水表面的气-液界面失稳条件与演化规律，并将通过实验研究对数值模拟结果以及二者的失效机理进行验证。

A tiny amount of polymer additive can suppress turbulent flow and reduce friction drag. Polymer additive is an important way for drag reduction and flow control. However, the polymeric moleculars suffer from scission of the high molecular chain by the high shear rate of the intensive turbulent flow. Consequently, it leads to the failure or reduced performance of polymer, which restricts its application severely. An effective slip is expected on the flow over superhydrophobic surface. Therefore, superhydrophobic surface has extensive applications such as anti-fouling and drag reduction. However, the high pressure and strong diffusion ambient condition could reduce the longevity of air layer and result in the failure of the material. Based on the flow characteristics of each technology, we aim to study the influence of synergetic drag reduction of polymer additives and superhydrophobic surface on the failure of both technologies. On one hand, the polymer additive could suppress the turbulent diffusion of air layer of superhydrophobic material to the ambient liquid, and reduce the peak pressure so that the failure of superhydrophobic material could not happen. On the other hand, the effective slip of superhydrophobic surface could reduce the peak shear rate in turbulent flow. Then the degradation of polymer could be avoided. In this project, the competitive mechanism of the maximum drag reduction and the range of application of the both technology on drag reduction will be studied by numerical simulation. Furthermore, Level-Set and immersed boundary method as well as the influence of surface tension would be implemented in numerical software to simulate the real physical characteristics of superhydrophobic surface in order to study the stability condition and the evolution of gas-liquid interface. Experimental study will be carried out in order to evaluate the numerical results and validate the failure mechanism of both technologies.