Hydrodynamics of bubble motion and oscillatory flows

气泡运动和振荡流的流体动力学

• 批准号: 0072228
• 负责人: Demetrios Papageorgiou
• 金额: --
• 依托单位: New Jersey Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2004-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0072228&HistoricalAwards=false
• 关键词: Hydrodynamics; bubble; motion; oscillatory; flows

0072228PapageorgiouThis work addresses computationally and analytically two classes of fluid dynamics problems. The motion of bubbles through fluids containing soluble surfactants is considered first. Experiments show that even trace amounts of surfactants can increase the drag on moving bubbles significantly. Through careful modeling, asymptotic analysis and direct numerical simulations of the Navier-Stokes equations coupled with the surfactant equations in the bulk and on the interface, we address both the steady and unsteady problems and in particular evaluate the effect of surfactants on wake size and control. Such controls are desirable in enhanced interphase mass transfer systems. In parallel, we will also study a class of exact Navier-Stokes solutions which emerges in models of lubrication bearing flows. We have found that such exact solutions can describe the viscous flow between two plates when one or both of the plates move normal to themselves. When this boundary motion is periodic, chaotic solutions can emerge at sufficiently high but order one Reynolds numbers. These flows are underlying flows whose stability to wavelike disturbances is highly complicated since the baseflow is chaotic to begin with. We consider such local flows when they are embedded into finite geometries. Direct Navier-Stokes computations will be performed in many geometries and high frequency limits analyzed asymptotically, in order to predict transitions to chaos.This work studies mathematical problems in fluid dynamics leading to scientific computations and analytical problems. The models arise from applications concerned with enhancing technological processes such as materials processing in microgravity, environmental and chemical processes, biomedical applications and lubrication technologies. We use a combination of mathematical and computational tools and intensive computations to elucidate and identify regimes and mechanisms that can enhance the efficiency of the applications mentioned above. For example, we identify, using simulations, situations where flow in squeeze bearings can stay laminar rather than become chaotic. Chaotic flows can cause the equipment to fail with disastrous effects on machinery. Modeling and simulations have the advantage, over experiments, of allowing wide parameter studies and hence help identify critical experiments and design strategies. The research is valuable in both benchmarking large scale simulations as well as providing direct comparisons with experiments.

0072228 Papageorgiou这项工作解决了计算和分析两类流体动力学问题。首先考虑气泡通过含有可溶性表面活性剂的流体的运动。实验表明，即使是微量的表面活性剂也会显著增加移动气泡的阻力。通过仔细的建模，渐近分析和直接数值模拟的Navier-Stokes方程与表面活性剂方程的散装和接口上，我们解决了稳定和非定常的问题，特别是评估效果的表面活性剂的尾流大小和控制。这种控制在增强的相间质量传递系统中是期望的。同时，我们也将研究一类精确的Navier-Stokes解出现在模型的润滑轴承流。我们已经发现，这种精确解可以描述两个板之间的粘性流动时，一个或两个板垂直于自己的运动。当这种边界运动是周期性的，混沌的解决方案可以出现在足够高，但顺序一雷诺数。由于基流开始是混沌的，这些流动是基本流动，其稳定性波动干扰是非常复杂的。我们认为这样的局部流时，他们被嵌入到有限的几何形状。直接Navier-Stokes计算将在许多几何形状和高频率限制进行渐近分析，以预测过渡到混沌。这项工作研究流体动力学的数学问题，导致科学计算和分析问题。这些模型产生于与加强技术过程有关的应用，如微重力下的材料加工、环境和化学过程、生物医学应用和润滑技术。我们使用的数学和计算工具和密集的计算相结合，以阐明和确定制度和机制，可以提高上述应用程序的效率。例如，我们确定，使用模拟，挤压轴承中的流动可以保持层流，而不是变得混乱的情况。混乱的流动会导致设备故障，对机器造成灾难性的影响。建模和仿真的优势，实验，允许广泛的参数研究，因此有助于确定关键的实验和设计策略。该研究在基准大规模模拟以及提供与实验的直接比较方面都很有价值。