平面上液滴蒸发导致液滴内自发形成耦合的法向温度梯度和切向温度梯度，由此产生耦合Marangoni对流，其失稳机制和耗散结构特征尚不清楚。项目拟通过线性稳定性分析确定耦合对流可能的失稳模式及临界条件，分析Ma数、Re数、Nu数、蒸发数E、Pr数及接触角对它们的影响，切实了解其稳定性；分析流动和传热过程与温度扰动和速度扰动的动力学关系，阐明耦合对流的失稳机制；通过能量收支分析计算Marangoni效应、蒸发冷却、热对流、热扩散、粘性耗散对耦合对流不稳定性的能量贡献，分析它们与失稳模式的深层次关系，深入理解耦合对流失稳的物理机理；三维数值模拟结合实验观测认识耗散结构的演变规律和细微特征，与BM对流失稳和热毛细对流失稳比较，认识耦合对流失稳与它们的根本区别。研究对理解平面上液滴蒸发诱发耦合Marangoni对流不稳定性、提高功能材料喷墨打印质量、改善DNA芯片制作技术具有重要的学术价值和指导意义。

Normal temperature gradient and tangential temperature gradient are spontaneously coupled in evaporating sessile droplet on a flat plate. The coupled Marangoni convection is thus occurred in the sessile droplet and its instability mechanism and characteristics of dissipative structure are not yet known up to date. In this proposal the possible instability models of coupled Marangoni convection and its critical conditions for the incipience of them will be determined firstly by linear stability analysis. The influences of Ma, Re, Nu, E, Pr and contact angle on them will be investigated and the stability of the coupled Marangoni will be understood clearly. Through analyzing the dynamic relationship between fluid flow, heat transfer and temperature perturbation and velocity perturbation, the instability mechanism of coupled Marangoni will be discovered clearly. Then, the energy contributions of Marangoni effect, the evaporating cooling effect, heat convection, heat diffusion and viscous dissipation on the instability will be calculated respectively by energy budget analysis. Their deeply relationship between the energy contributions and the instability models will be explained and then the physical mechanism of coupled Marangoni instability will be comprehended. Finally, by combining experiments and three-dimensional simulations, the evolution law and three-dimensional characteristics of fluid flow and heat transfer of the dissipative structure will be investigated. By comparing with BM convection instability and thermocapillary convection instability, the fundamental discrepancy between them will be understood. This study has important values not only for deeply understanding the instability of coupled Marangoni convection in evaporating sessile droplet on flat plate, but also for improving the quality of ink-jet printing of function materials and improving the DNA mapping technology and etc.