UM-SJTU Joint Institute, Shanghai Jiao Tong University, Shanghai, China.
Phys Rev E. 2017 Jun;95(6-1):063112. doi: 10.1103/PhysRevE.95.063112. Epub 2017 Jun 21.
For jet flow emanating from noncircular orifices, an unbalanced surface tension force leads to capillary instability, which is independent of influence from the ambient air in the Rayleigh regime. In the present article, the dynamic behavior of incompressible elliptical jets in the Rayleigh regime is investigated. Theoretically, with the consideration of the fluid viscosity, the solution of the Cosserat equation consists of a particular solution and a complementary solution. For the complementary solution the wave number of disturbance modes has two complex conjugate roots, which are responsible for the jet breakup. To match the nonzero particular solution, a spatial wave needs to be introduced, which is independent of external perturbations. Physically, such a spatial wave is interpreted as the axis-switching phenomenon. The predicted features of the axis-switching wavelength and the damping effect from the fluid viscosity have been successfully verified by experimental results. Moreover, the dispersion relations from the present theory suggest that the growth rate of spatial instability is influenced by orifice eccentricity, the Weber number, and the Ohnesorge number.
对于非圆形孔口射出的射流，不平衡的表面张力会导致毛细不稳定性，这在瑞利区与环境空气的影响无关。本文研究了瑞利区不可压缩椭圆射流的动力学行为。从理论上考虑流体粘度，Cosserat 方程的解由特解和补解组成。对于补解，扰动模态的波数有两个复数共轭根，这是射流分裂的原因。为了匹配非零特解，需要引入一个与外部扰动无关的空间波。从物理上看，这样的空间波可以解释为轴切换现象。通过实验结果，成功验证了轴切换波长和流体粘度阻尼效应的预测特征。此外，本理论的频散关系表明，空间不稳定性的增长率受孔口偏心度、韦伯数和奥内索格数的影响。
