超临界Bénard -Marangoni对流斑图的时空演化和混沌特性

Bénard-Marangoni convection is an important natural convection in microgravity. The strategic blueprint of microgravity hydrodynamics made by the NSFC and CAS point out that the feature of basic flow and instability in Marangoni convection is the key research direction. However, the researchers focused on the onset instability of the convection, the spatiotemporal evolution and chaotic characteristics of the supercritical convection is a whole new topic. This project will conduct experimental research on the transition to turbulence, which employ plenty of the technique such as PIV, infrared image and laser distance detector, to measure the velocity field, temperature field and free surface displacement. We divide the supercritical flow into 3 region: low supercritical, supercritical and high supercritical, in which each scientific problem is different. In the low supercritical range, pattern formation and its mechanism will be studied. In the supercritical range, we will involve chaos theory to research the routes to turbulence. In the high supercritical range, the feature of surface-driven turbulence will be analyzed. This work will explore the novel phenomenon and mechanism in supercritical pattern formation, which will broaden the knowledge of surface-driven turbulence.

Bénard-Marangoni对流是微重力条件下重要的流动形式。在基金委和中科院联合提出的空间学科布局中，将Marangoni对流的基本流动特征和运动的不稳定性列入重点研究方向。过去的主要研究是针对临界不稳定，而超临界Bénard -Marangoni对流斑图的时空演化和混沌特性是一个全新的课题。本项目将开展高Ma数下，Bénard-Marangoni对流转捩过程的实验研究，结合粒子图像测速、红外测温、激光测距等多项实验技术，开展温度场、速度场、自由面位移的诊断，观测流场结构的演化和自由面的变化。根据超临界数大小，我们将超临界对流界定为三个区域，明确区域研究科学问题。在低超临界区，将研究斑图转换和演化机理等。在超临界区，将用混沌理论研究流动向湍流转捩的途径，在高超临界区，将分析BM湍流的特征。本项目将探索超临界流动斑图演化和转捩新现象和新机制，丰富人们对界面驱动湍流的认识。

随着人们对非线性效应引起的自组织以及耗散结构的认识，斑图动力学未来将可能在材料制备、化学工程、生命科学等有重要应用。本项研究关注热毛细流动引起的Bénard-Marangoni对流的斑图结构在超临界条件下的时空演化行为和混沌特性，并开展实验和理论研究工作。建立了一套可在不同超临界条件开展Bénard-Marangoni对流的实验装置，并可以采用多种流动显示技术对流场进行全面观测，可实现红外热像仪表面温度场，PIV(粒子图像测速技术)、LDV(激光多普勒测速)，热电偶测温等实验测量手段。我们观察到流动斑图在临界和超临界条件下的失稳和转捩过程，获得波数选择在超临界不稳定的变化趋势，认识高超临界条件的斑图演化过程和混沌动力学特征，发现精细流动结构相互作用流动振荡过程。开发了一套基于谱方法对斑图动力学方程进行数值模拟的程序，可模拟六边形涡胞、卷圈涡胞等非线性演化过程。提出一种基于实验测量场的非线性动力学分析方法，获得斑图演化的非线性模型方程，有助于我们研究斑图形成、竞争和演化的动力学特征和规律。