Catastrophic transition to turbulence in rotation-dominated flows

洛佩兹，胡安1336410在背景旋转占主导地位的漂浮中，科里奥利加速提供的恢复力可以抑制径向运动，或导致振荡行为。这种流动广泛应用于机械工程(旋流燃烧器、旋转机器)、航空航天(涡流产生的升力、自旋稳定航天器的燃料箱)、矿物加工(混合、悬浮和分离)、地球物理(熔融行星核、热带气旋)。智力价值：重点是理解在受控旋转中从层流状态到湍流状态的灾难性转变。虽然有实验证据证明这一现象，但对于潜在的物理机制还没有达成共识。两种主要的解释是，相变要么来自无粘模的共振，要么直接作为基本态的不稳定性。PI建议通过理论、数值和实验研究来解决这一争论。PI实验室的模拟和分析将与国际合作者进行的实验相辅相成。将考察进动旋转流动(其中驱动机制是旋转矢量的时间变化)和通过振荡的斯托克斯层与背景旋转的相互作用而产生大惯性波响应的流动(旋转矢量是X的)。研究方法将基于粘性水的直接数值模拟和稳定性分析，以便所有的动力学都可以被研究并直接与实验相匹配。广泛的影响：要调查的科学问题是近50年来一直吸引研究人员的基本问题，具有许多潜在的重要应用，如上所述。该项目包括由具有数十年跨学科研究经验的导师对研究生进行跨学科培训。作为更大的国际合作的一部分，将有大量的互访机会，为所有参与者提供宝贵的培训和指导经验。我们将继续参与本科生的研究经验，在那里，问题的各个方面将被分离到适合本科生的项目中。对于更广泛的社区，项目中开发的所有解算器都将免费提供。

Lopez, Juan 1336410 In floows with dominant background rotation, Coriolis accelerations provide restoring forces that can act to suppress radial motion, or lead to oscillatory behavior. Such flows are found in a wide range of applications in mechanical engineering (swirl burners, rotating machines), aerospace(vortex-generated lift, fuel tanks of spin-stabilized spacecraft), minerals processing (mixing, suspension and separation), to geophysics (molten planet cores, tropical cyclones). Intellectual Merit:The focus is on understanding the catastrophic transition from laminar to turbulent states in contained rotating flows. While there is experimental evidence for this phenomenon, no consensus exists as to the underlying physical mechanism. The two dominant interpretations are that the transition arises either from resonance of inviscid modes or directly as an instability of the basic state. The PI proposes to resolve this argument by using theoretical, numerical and experimental studies. Simulations and analysis at the PI's laboratory will be complemented with experiments conducted by international collaborators. Precessing rotating flows (where the driving mechanism is temporal variation of the rotation vector) and flows that generate large inertial wave responses through interaction of oscillatory Stokes layers with background rotation (rotation vector is fixed) will be examined. The research approach will be based in direct numerical simulation and stability analysis of viscous flows, so that all the dynamics can be studied and directly matched to experiments.Broader Impacts:The scientific problem to be investigated is a fundamental issue that has intrigued researchers for nearly 50 years, and has many potentially important applications, as already mentioned above.This project includes interdisciplinary training of graduate students by mentors who have decades of interdisciplinary research experience between them. Being a part of a larger international collaboration, there will be ample opportunities for exchange visits, providing a valuable training and mentoring experience for all involved. Our involvement with research experiences for undergraduates will be continued, where aspects of the flow problems will be isolated into projects suitable for undergraduates. For the broader community, all solvers developed in the project will be freely and readily available.