粘弹性流体带电射流非线性稳定性研究

In the last decades electrospraying and electrospinning have attracted wide attention due to their intriguing advantages and potential industrial applications. Meanwhile, the electrohydrodynamic phenomena existing in electrospraying and electrospinning experiments provide abundant background and content for basic theoretical and experimental research. Particularly, polymer materials of high molecule are frequently used in electrospraying and electrospinning experiments, which are within the scope of viscoelastic fluids. However, owing to the complexity of the problem itself, up to now only a few reports on electrified jets have considered the viscoelasticity of liquid. Taking electrospraying and electrospinning as research background, and taking electrified Newtonian and viscoelastic liquid jets as research objects, in this project we use the theoretical, numerical and experimental methods to study, respectively, the local absolute and convective instability, linear global stability, long-wave nonlinear instability of the axisymmetric mode and three dimensional nonlinear instability of the Newtonian and viscoelastic liquid jets under radial electric field. We also study the effects of the electric field and liquid physical properties, such as viscoelasticity and surface tension, on the instability of the axisymmetric and first non-axisymmetric modes, aiming to provide instructive suggestions for practical applications.

近年来，由于它们的独特优势和应用潜力，电雾化和电纺丝一直受到工业界的广泛关注。同时，电雾化和电纺丝中存在的电流体力学现象为基础理论和实验研究提供了丰富的背景和内容。特别，在电雾化和电纺丝实验中经常使用高分子聚合体材料，它们属于粘弹性流体的范畴。而由于问题的复杂性，目前只有少数的带电流体射流研究考虑了流体的粘弹性性质。本项目以电雾化和电纺丝为研究背景，以牛顿流体和粘弹性流体带电射流为研究对象，采用理论推导、数值模拟和实验观测相结合的方法，分别研究牛顿流体和粘弹性流体在径向电场作用下的局部绝对与对流不稳定性、线性整体稳定性、轴对称模式的长波非线性不稳定性以及三维非线性不稳定性，研究电场及粘弹性、表面张力等物性参数对射流轴对称和第一非轴对称模式的不稳定行为的影响规律，为实际应用提供指导性建议。

本项目以近年来备受关注的电雾化和电纺丝为研究背景，考虑到在电雾化和电纺丝中经常使用高分子聚合物材料，而这些高分子聚合物的溶液属于粘弹性流体的范畴，因此在原有工作的基础上，进行了粘弹性流体带电射流非线性稳定性的研究。该研究不仅有助于我们了解电雾化和电纺丝中射流的不稳定行为和影响因素，为实际应用提供指导和建议，而且作为基础性理论研究，丰富了电流体力学和非牛顿流体力学的内容。本项目的主要研究内容包括粘弹性流体带电射流的绝对与对流稳定性分析、整体线性稳定性分析、长波即一维非线性稳定性分析、二维/三维非线性稳定性分析以及实验观测射流不稳定行为，其中，一维非线性稳定性分析内容最为丰富，我们构造了一个基本的理论模型，并用此模型全面而详细地研究了径向电场作用下粘弹性导电射流的非线性不稳定特性，通过大量的数值计算，给出了电场强度、粘弹性、表面张力等主要参数的影响规律。本项目在Physics of Fluids、Journal of Non-Newtonian Fluid Mechanics、Microfluidics and Nanofluidics、European Journal of Mechanics B/Fluids等国际知名流体力学期刊上发表论文7篇。