Vortex dynamics and energy transfer in turbulent 3D bluff-body wakes.

崖体是对工业和环境重要性的各种流动几何形状的诊断简化，例如：独立结构（建筑物，桥梁，风力涡轮机）；混合装置（燃烧器、化学反应器或热交换器）；崎岖不平的城市地形。障碍物表面的流动分离过程产生了高能量、大范围的旋转和再循环流动区域。这些连贯的流动结构相互作用，造成速度场的扭曲，导致能量转移到更小但更激烈的运动中，这些运动向下游传播，并导致高度集中的速度波动（湍流）、非定常力和增强的混合。目前的计划解决了理解这些流动和设计设备的基本和应用挑战：开发稳健和统计客观的技术来表征非定常流动行为，制定数学框架来建模和控制这些流动；以及对几何和入射流条件如何影响流物理的基本理解。五年的研究目标是了解和控制表面陡坡体湍流尾迹的动力学；重点研究了入射边界层、障碍物几何形状和尖端流动相互作用对湍流特性和流动演化的影响。这项工作的基础是广义诊断条件平均技术的发展，客观地表示连贯和湍流运动。该方法为研究能量传递和流动控制策略的动态一致降阶数学模型奠定了基础。该计划的成果是与基础研究和实践相关的重要科学和工程进展。该研究涉及预测和控制。提出的实验是启发式简化，旨在提供与流动装置，流固相互作用，混合过程和环境安全相关的尾流基本物理的见解。广义条件平均方法允许通过分离确定性（相干）和随机（湍流）能量贡献来分析非定常流动行为的新颖、动态一致的方法。例如，由此产生的表示提高了非稳态负荷预测的准确性，并为指导湍流模型的开发提供了新的见解。这种方法可以推广到结构动力学和噪声产生的研究。降阶公式是流量控制策略的基础，例如抑制压缩机或风力涡轮机叶片的噪声产生或失速。该技术可以通过提供快速的交互式可视化工具来改进设计实践，该工具能够隔离和建模工程相关的流量，而无需求助于广泛且耗时的模拟程序。在这个项目中，高素质的人员接受了最先进的光学技术、遥感技术、数学和计算工具方面的培训。重点是发展流体力学基础及其在工业驱动工程开发中的应用方面的强大专业知识。培训的跨学科性质得到国际和国家合作的补充。该策略旨在培养独立的工程师，具有良好的批判性判断和灵活的技能。该计划对加拿大的潜在好处是：提高工业竞争力和降低温室气体排放（例如改善飞机发动机和风力涡轮机的性能）；风害缓解;新技术和先进人才的培养。

Bluff-bodies are diagnostic simplifications for a wide range of flow geometries of industrial and environmental importance such as: free-standing structures (buildings, bridges, wind turbines); mixing devices (in combustors, chemical reactors or heat exchangers); rough and urban terrain. The flow separation process on the obstacle surfaces gives rise to highly energetic, large-scale regions of rotating and recirculating flow. These coherent flow structures interact, causing distortions of the velocity field leading to energy transfer to smaller but more intense motions, which travel downstream and are responsible for high levels of concentrated velocity fluctuations (turbulence), unsteady forces and enhanced mixing. The present program addresses fundamental and applied challenges for understanding these flows and designing devices: the development of robust and statistically objective techniques to characterize unsteady flow behaviour, the formulation of a mathematical framework for modelling and controlling these flows; and a fundamental understanding of how geometry and incident flow conditions affect the flow physics.The five-year research objectives are to understand and control the dynamics of turbulent wakes for surface-mounted bluff-bodies; focusing on the influence of the incident boundary layer, obstacle geometry and tip-flow interactions on turbulence characteristics and flow evolution. This work is underpinned by the development of generalized diagnostic conditional averaging techniques to objectively represent coherent and turbulent motion. This approach sets the basis for dynamically consistent reduced-order mathematical models to investigate energy transfer and flow control strategies.The outcomes of this program are important scientific and engineering advances relevant to fundamental studies and practice. The research addresses prediction and control. The proposed experiments are heuristic simplifications designed to provide insights in the underlying physics of wake flows pertinent to flow-devices, fluid-structure interactions, mixing processes and environmental safety. The generalized conditional averaging methodology permits novel, dynamically consistent approaches for analysing unsteady flow behaviour by separating deterministic (coherent) and stochastic (turbulent) energetic contributions. The resulting representation, for example, improves the accuracy of unsteady-load predictions and yields new insights to guide turbulence model development. This approach can be extended to studies of structural dynamics and noise generation. The reduced-order formulation is a cornerstone of flow control strategies, e.g. to suppress noise generation or stall on compressor or wind turbine blades. This technique can improve design practice by providing a rapid interactive visualisation tool, capable of isolating and modelling engineering relevant flow quantities, without recourse to extensive and time-consuming simulation procedures. In this program highly qualified personnel are trained in state-of-the-art optical techniques, remote-sensing technologies, mathematical and computational tools. The focus is to develop a strong expertise in fluid mechanics fundamentals and their applications to industry driven engineering developments. The interdisciplinary nature of the training is supplemented by international and national collaborations. This strategy aims to develop independent engineers, with sound critical judgment and flexible skills.The program’s potential benefits to Canada are: increased industry competitiveness and lower greenhouse gas emissions (e.g. improved aircraft engine and wind turbine performance); wind-damage mitigation; new technologies and advanced training of highly qualified personnel.