The effect of suspended particles on Rayleigh-Bénard buoyant thermal convection

悬浮颗粒对瑞利-贝纳德浮力热对流的影响

• 批准号: 2053204
• 负责人: Daniel Floryan
• 金额: $ 24.38万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2053204&HistoricalAwards=false
• 关键词: effect; suspended; particles; Rayleigh; nard

Flows with suspended particles are widespread in natural and technological systems such as fluidized beds, solar collectors, chemical processing, rain formation, magmas with suspended crystals and many others. However, their computational study has been limited by the inherent complexity of the simulations required. In particular, little is known about heat transfer in particulate flows. The present project addresses a canonical problem in this broad class, namely the effect of suspended particles on buoyant Rayleigh-Bénard thermal convection, the flow in a fluid layer heated from below and cooled from above. The particle-free version of this problem has been the subject of extensive studies due to its centrality in many branches of physics and engineering, but the effect of particles has barely been scratched. The work proposed here seeks to answer fundamental questions by identifying the significant flow regimes in particulate natural convection and quantifying the heat transfer modifications that particles introduce. This research will influence turbulence and heat transfer models used in common industrial or geophysical simulations, including those of the atmosphere, the oceans, the earth core and climate. It also has the potential to help the development of renewal energy sources, such as those based on solar collectors and hydrogen production. To advance our knowledge of particulate heat transfer, the proposed work will make use of models of increasing realism and complexity. A simplified linear analysis of Rayleigh-Bénard stability will provide an orientation on the effect of basic control parameters such as the particle-to-fluid density and heat capacity ratios, the fluid Prandtl number, and the mass and thermal loading. The point-particle model will be used to elucidate the regions of parameter space where heat transfer can be expected to be substantially modified in the turbulent regime. The culmination of the project consists in fully resolved particulate simulations using the numerical method Physalis, implemented in a highly-optimized multi-GPU code, which is able to resolve flows with many thousands of suspended particles. In this way the particle-fluid momentum and heat exchanges can be calculated from first principles avoiding the ad hoc parametrization necessary with the point-particle model. These simulations will be focused on situations of particular interest uncovered by the simplified models and will permit a much more detailed and deeper understanding of the physics involved in effects such as heat transfer enhancement and particle clustering, among others.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.

带有悬浮颗粒的流动在自然和技术系统中广泛存在，例如流化床、太阳能收集器、化学处理、雨形成、带有悬浮晶体的岩浆和许多其他系统。然而，他们的计算研究受到所需模拟的固有复杂性的限制。特别是，很少有人知道颗粒流中的传热。本项目解决了这一广泛类别中的一个典型问题，即悬浮颗粒对浮力Rayleigh-Bénard热对流的影响，即从下面加热并从上面冷却的流体层中的流动。这个问题的无粒子版本一直是广泛研究的主题，因为它在物理学和工程学的许多分支中处于中心地位，但粒子的影响几乎没有被触及。这里提出的工作旨在通过确定颗粒自然对流中的重要流型和量化颗粒引入的传热修改来回答基本问题。这项研究将影响常见的工业或地球物理模拟中使用的湍流和传热模型，包括大气，海洋，地核和气候。它还具有帮助开发可再生能源的潜力，例如基于太阳能收集器和氢气生产的能源。为了提高我们对颗粒传热的认识，拟议的工作将利用越来越现实和复杂的模型。瑞利-贝纳德稳定性的一个简化的线性分析将提供一个方向的基本控制参数，如颗粒与流体的密度和热容比，流体的普朗特数，质量和热负荷的影响。点粒子模型将用于阐明参数空间的区域，在该区域中，可以预期在湍流状态下传热将被大幅修改。该项目的高潮在于使用数值方法Physalis进行完全解析的颗粒模拟，该方法在高度优化的多GPU代码中实现，能够解析具有数千个悬浮颗粒的流动。通过这种方式，可以从第一原理计算颗粒-流体动量和热交换，避免了点颗粒模型所必需的特设参数化。这些模拟将集中在简化模型所揭示的特别感兴趣的情况下，并将允许更详细和更深入地了解涉及传热增强和粒子聚集等效应的物理学。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和更广泛的影响审查标准进行评估，被认为值得支持。