湍流流动中鲨鱼皮表面流体减阻研究进展

SHARK-SKIN SURFACES FOR FLUID-DRAG REDUCTION IN TURBULENT FLOW: A REVIEW Brian Dean Bharat

快速游动的鲨鱼,其皮肤表面沿流动方向有序地排列着沟槽状结构,人们认为这种结构能在湍流流动中减小表面摩擦阻力.人们仿真这种生物结构来进行实验研究和应用,通过复制和改善鲨鱼皮肤表面沟槽状结构,使得摩擦阻力最大减小了近10%.在实验和模拟仿真中,人们不断讨论和研究湍流流动阻力的形成机制和沟槽减阻的理论特性.本文综述了沟槽减阻理论特性的一些研究方法,并且归纳定义了沟槽减阻最优几何形状及其尺寸;详细考虑流体流动的特点,给出了一种用来选择最优沟槽形状及其尺寸的方法;综述了目前的沟槽加工制造技术.由于鲨鱼皮肤表面存在少量黏液,从仿生学的角度,文章最后综述并展望了通过局部应用疏水性材料来改变沟槽附近流场属性,从而达到更大程度上减小阻力的目标.

The skin of fast-swimming sharks exhibits riblet structures aligned in the direction of flow that are known to reduce skin friction drag in the turbulent-flow regime. Structures have been fabricated for study and application that replicate and improve upon the natural shape of the shark-skin riblets, providing a maximum drag reduction of nearly 10 percent. Mechanisms of fluid drag in turbulent flow and riblet-drag reduction theories from experiment and simulation are discussed. A review of riblet-performance studies is given, and optimal riblet geometries are defined. A survey of studies experimenting with riblet-topped shark-scale replicas is also given. A method for selecting optimal riblet dimensions based on fluid-flow characteristics is detailed, and current manufacturing techniques are outlined. Due to the presence of small amounts of mucus on the skin of a shark, it is expected that the localized application of hydrophobic materials will alter the flow field around the riblets in some way beneficial to the goals of enhanced drag reduction.