Investigation of the dynamics of large-scale circulation patterns in turbulent convection cells at very large aspect ratios with direct numerical simulations and experiments in compressed sulfur hexafluoride

通过压缩六氟化硫中的直接数值模拟和实验研究非常大纵横比的湍流对流室中大规模环流模式的动力学

• 批准号: 255352004
• 负责人: Dr. Christian Resagk
• 金额: --
• 依托单位: Technische Thermodynamik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/255352004?language=en
• 关键词: Investigation; dynamics; large; scale; circulation

Many turbulent convection processes in nature and technology are present in extended layers or boxes and show hierarchies of regular ordered flow patterns although the corresponding Rayleigh and Reynolds numbers suggest a fully developed turbulence. In this project we want to study this spatio-temporal dynamics of large-scale structure formation in detail. Therefore, experiments with compressed sulfur hexafluoride will be combined with massively parallel direct numerical simulations based on a spectral element method. Both approaches will allow for convection studies in very large aspect ratio systems at Rayleigh numbers that were not accessible before. The analyses will clarify if such large-scale circulation patterns are relics persisting all the way from the onset of convection and the weakly nonlinear regime into the full turbulent regime. We want to identify the time scales on which the patterns evolve and investigate their Rayleigh number dependence. The experiment allows us to study the robustness of the circulation patterns with respect to non-Boussinesq effects. Based on the simulations, we want to develop amplitude models which can describe the patterns by means of a few dominant degrees of freedom giving rise to the possibility of a control of these patterns in technological applications.

自然界和技术中的许多湍流对流过程都存在于扩展层或盒中，并显示出规则有序的流型层次，尽管相应的瑞利数和雷诺数表明湍流充分发展。在这个项目中，我们希望详细研究这种大规模结构形成的时空动力学。因此，压缩六氟化硫的实验将结合大规模并行直接数值模拟的基础上，光谱元素的方法。这两种方法将允许在非常大的纵横比系统在瑞利数，以前是无法访问的对流研究。分析将澄清，如果这样的大规模的环流模式的遗迹坚持所有的方式从对流和弱非线性制度到充分的湍流制度。我们要确定的时间尺度上的模式演变，并调查其瑞利数的依赖。该实验使我们能够研究的鲁棒性的循环模式相对于非Boussinesq效应。基于模拟，我们要开发振幅模型，它可以描述的模式，通过几个主要的自由度引起的可能性，这些模式在技术应用中的控制。

项目成果

Koopman analysis of the long-term evolution in a turbulent convection cell

• DOI: 10.1017/jfm.2018.297
• 发表时间: 2018-07-25
• 期刊: JOURNAL OF FLUID MECHANICS
• 影响因子: 3.7
• 作者: Giannakis, Dimitrios;Kolchinskaya, Anastasiya;Schumacher, Joerg
• 通讯作者: Schumacher, Joerg

Assessment of horizontal velocity fields in square thermal convection cells with large aspect ratio

大纵横比方形热对流单元水平速度场评估

• DOI: 10.1007/s00348-018-2626-9
• 发表时间: 2018
• 期刊: Experiments in Fluids
• 影响因子: 2.4
• 作者: Kästner;Christian;Resagk;Christian;Westphalen;Jasper;Junghähnel;Manuela;Cierpka;Christian;Schumacher
• 通讯作者: Schumacher

Large-scale mean patterns in turbulent convection

• DOI: 10.1017/jfm.2015.316
• 发表时间: 2015-08-01
• 期刊: JOURNAL OF FLUID MECHANICS
• 影响因子: 3.7
• 作者: Emran, Mohammad S.;Schumacher, Joerg
• 通讯作者: Schumacher, Joerg