温度梯度下液桥紧缩过程的模拟研究

Simulation of Liquid Bridge Contraction Process under Temperature Gradient

摘要: 带有温度梯度的液桥紧缩是自然界和工业生产中的常见现象，液桥的断裂行为对于印刷、喷墨过程起着关键的影响。本文通过数值模拟分析了表面张力梯度和粘性力梯度对液桥在微重力环境下紧缩过程的作用。通过分析四个时刻的自由面轮廓、轴向速度和压强以及断裂时刻液桥速度和压强云图，阐明了液桥的断裂点位于表面张力较大或粘性力较小一侧的形成机理。同时随着表面张力梯度的增大液桥的轴向速度和压强的梯度也增大。最后分析了在表面张力梯度和粘性力梯度同时作用下，表面张力和粘性力的抗衡作用直接影响液桥的轮廓，最后断裂时刻液桥形态结合了仅表面张力梯度作用下的长锥型和仅粘性力梯度作用下的细丝状。该研究为实际工业应用中液桥在温度梯度下的断裂问题提供了模拟基础。

Abstract: The shrinkage of liquid bridge with temperature gradient is a common phenomenon in nature and industrial production. The fracture behavior of liquid bridge plays a key role in the process of printing and inkjet. In this paper, the effects of surface tension gradient and viscous force gradient on the contraction process of liquid bridge in microgravity environment are analyzed by numerical simulation. By analyzing the free surface profile, axial velocity and pressure at four times and the cloud diagram of liquid bridge velocity and pressure at the time of fracture, the formation mechanism of the fracture point of liquid bridge on the side with large surface tension or small viscous force is clarified. At the same time, with the increase of surface tension gradient, the gradient of axial velocity and pressure of liquid bridge also increases. Finally, it is analyzed that under the simultaneous action of surface tension gradient and viscous force gradient, the counterbalance effect of surface tension and viscous force directly affects the profile of the liquid bridge. Finally, the shape of the liquid bridge at the time of fracture combines the long cone type under the action of surface tension gradient only and the filament type under the action of viscous force gradient only. This study provides a simulation basis for the fracture of liquid bridge under temperature gradient in practical industrial application.