RII Track-4: NSF: Simulation and Modeling of Turbulent Flow Control via Flow-Dependent Anisotropic Surface Textures

流动分离是当流体粒子减速并且不能遵循表面形状时发生的现象。它有几个负面影响的阻力和升力，是至关重要的能源消耗和排放，飞机的机动性，涡轮机噪音，振动等，拟议的研究是出于观察，皮肤dennelling（坚韧的鳞片）鲨鱼皮肤显示有前途的性能，在减少流体动力阻力。鲨鱼在鱼类世界中独特的皮肤动态响应流量的能力提供了比当前流量控制技术显著的性能优势。该奖学金的目的是获得一个新的基本理解的因果机制与鲨鱼皮denaltation的减阻作用，同时推进目前的数值模型，为常规工业设计。在EPSCoR RII Track-4：NSF奖学金的支持下，PI将学习模拟和分析流体-结构相互作用，并通过斯坦福大学湍流研究中心（CTR）的培训为数值预测工具开发新模型。该研究金将加强密西西比大学和斯坦福大学之间的合作，并促进与中南部和密西西比州的航空、航天和海军工业有关的新的经济发展机会。鲨鱼齿垢的弹性锚定使它们在受到分离开始时发生的反向分离流时能够竖起鬃毛，从而阻碍局部分离。当附着流动时，附着物返回到非刚毛位置并形成类似条纹的纹理以减少摩擦阻力。这种运动导致了一个依赖于流动的各向异性（或方向）的功能，这表明一个被动的，流动激活的分离控制技术。目前的方法，固定的表面粗糙度设计，不足以理解或预测复杂的流动可移动的微结构调制。该奖学金的总体目标是支持主要研究者在CTR的培训和合作研究。培训和研究将侧重于尖端的流体-结构相互作用模拟方法，以及开发和验证一种新的壁模型，用于预测表面微观结构所代表的复杂效应。具体目标包括：（i）生成可移动各向异性微结构上的流动的前所未有的数据集，（ii）获得关于非线性相互作用的新的基本理解，（iii）综合理解以开发阻力和动量通量的真正预测模型。这个RII Track-4：NSF奖学金将扩大PI的研究能力，并将他的职业道路转变为流固多物理系统和降阶模型开发的有前途的方向。由流动相关各向异性微结构实现的独特流动控制技术将对航空航天、农业、生物医学、能源、该奖项反映了NSF的法定使命，并通过使用基金会的智力价值进行评估，被认为值得支持和更广泛的影响审查标准。

Flow separation is the phenomenon that occurs when a fluid particle is slowed down and cannot follow the shape of the surface. It has several negative effects on drag and lift that are critical to energy consumption and emissions, aircraft maneuverability, turbine noise, and vibration, etc. The proposed research is motivated by the observation that dermal denticles (tough scales) on shark skin show promising performance in reducing hydrodynamic drag. The ability of sharks’ unique skin in the fish world to dynamically respond to the flow offers a significant performance advantage over current flow control techniques. This fellowship aims at gaining a new fundamental understanding of the causal mechanisms associated with the drag reduction role of shark skin denticles and simultaneously advancing current numerical models for routine industrial design. With the support of an EPSCoR RII Track-4:NSF Fellowship, the PI will learn to simulate and analyze fluid-structure interactions and develop new models for numerical predictive tools through the training at the Center for Turbulence Research (CTR) at Stanford University. The fellowship will strengthen collaboration between the University of Mississippi and Stanford, and promote new economic development opportunities related to aeronautics, aerospace, and naval industries in the mid-south and in the State of Mississippi.The elastic anchoring of shark denticles enables them to bristle when subjected to the reversing separated flow that occurs at the onset of separation, thus hindering local separation. When flow is attached, denticles return to the non-bristled position and form a riblet-like texture to reduce friction drag. This motion leads to a flow-dependent anisotropic (or directional) function of the denticles that indicates a passive, flow-activated separation control technique. Current approaches, designed for stationary surface roughness, are insufficient to understand or predict the complex flows modulated by movable microstructures. The overarching goal of this fellowship is to support the PI’s training and collaborative research at the CTR. The training and research will focus on the cutting-edge fluid-structure interaction simulation methods and the development and validation of a novel wall model for the prediction of complex effects represented by surface microstructures. Specific objectives include: (i) to generate an unprecedented dataset of flows over movable anisotropic microstructures, (ii) to gain a new fundamental understanding about non-linear interactions, (iii) to synthesize the understanding to develop truly predictive models for drag and momentum flux. This RII Track-4:NSF fellowship will expand the PI’s research capacity and transform his career path towards a promising direction in the fluid-solid multi-physics system and reduced-order model development. The unique flow control techniques achieved by the flow-dependent anisotropic microstructure will be highly transformative to many other research areas in aerospace, agricultural, biomedical, energy, and environmental engineering where the application of structures with directional function is needed for the flow control process.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.