为研究低电导率导电液滴的电场效应, 采用开源计算流体力学(CFD)软件OpenFOAM, 设计了一种基于漏介质模型(leaky dielectric model)和流体体积(volume of fluid, VOF)法的电流体雾化(electrohydrodynamic atomization, EHDA)求解器, 并将数值结果与Taylor的解析值进行了比较. 模拟结果预测了液滴的变形方式以及液滴内外的环流模式. 研究发现, 在外加电场作用下, 液滴会发生“扁长型”或“扁圆型”变形, 并在内部形成稳定的环流, 液滴只会发生变形, 而不会发生宏观运动; 随着电场强度的增加, 液滴的变形越来越大, 小变形情况下, 模拟值与理论值基本吻合, 验证了数值方法的正确性; 当液滴的变形量较大时, 模拟结果开始偏离理论值, 与实验观察结果一致. 此外, 电导率比值的改变对液滴变形的影响也比较明显, 而介电常数比的改变对液滴变形的影响则不太明显.
To study the electric field effect of conductive droplets with low conductivity, an electrohydrodynamic atomization (EHDA) solver based on the leaky dielectric model and the volume of fluid (VOF) method is designed by the computational fluid dynamics (CFD) software OpenFOAM. The numerical results are compared with Taylor’s analytical values, and the simulation results predict the deformation ways of droplets and the mode of circumfluence inside and outside the droplets. It is found that under the action of an external electric field, the droplets will become “prolate” or “oblate” and form stable circumfluence inside, and they only undergo deformation without any macroscopic motion. As the intensity of the electric field increases, the deformation of the droplets also intensifies. In the case of small deformation, the simulated values are consistent with the analytical values, which verifies the correctness of the numerical method. When the droplet deformation is considerable, the simulation results start to deviate from the theoretical values, which is consistent with the experimental observations. In addition, the effect of the change in conductivity on droplet deformation is also apparent, while the evolution of the dielectric constant ratio has a less pronounced impact on droplet deformation.