发表机构
University of California, Irvine（加州大学尔湾分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文用微扰理论预测低韦伯数下扁球液滴的变形与内部环流，结合边界层、环偶极子镜像及势流分析，给出速度场和压力场，并比较了精确解与微扰法的计算成本。
AI 中文摘要
液滴在气体中运动时，由于沿表面的气动压力变化，会从球形发生变形。本文针对以低韦伯数（We < 1）和雷诺数（Re = O(10)）在气体中平移的轴对称液滴，预测了其变形。该变形分析基于局部压力跃变与两个曲率半径之间的关系。考虑气液界面两侧的薄边界层，其中存在由压力梯度驱动流动（伴随大密度跃变）引起的表面速度跃变，以及由表面张力引起的压力跃变。以韦伯数 $We$ 作为微扰参数，预测了近椭球形状。随后，预测了准稳态的液相内部流函数和速度场，描述了内部环流和涡环结构，涡量分布在整个无粘液体中。气相在扁球液滴上的流动通过一个环偶极子作为液滴内的镜像来描述。环偶极子的半径与 $We$ 相关。给出了气体势流结果，并分别使用精确解析解和基于 $We$ 平方根的微扰分析进行了比较。微扰分析的计算成本较低。对局部曲率、液体环流和气体势流的三种分析被匹配起来，以得到速度场和压力场。镜像环偶极子的适当半径与 $We$ 的平方根相匹配。预测了两个流体中的流函数和两个速度分量以及气体势场。最后对液滴阻力进行了一些评论。
英文摘要
Liquid droplets deform from spherical shape due to aerodynamic variation of pressure along the surface as the droplet moves through a gas. The deformation is predicted for axisymmetric droplets translating through a gas with low Weber numbers, We < 1, and Reynolds number Re = O(10). That deformation analysis is based on the relations between local pressure jump and the two radii of curvature. A thin boundary layer on both sides of the gas-liquid interface is considered with a surface-velocity jump due to pressure-gradient-driven flow with a large density jump and a pressure jump due to surface tension. A near-ellipsoidal shape is predicted using $We$ as a perturbation parameter. Then, the quasi-steady internal liquid-phase stream function and velocity field are predicted, describing internal circulation and a vortex ring structure with vorticity distributed through an inviscid liquid. The gas-phase flow over the oblate droplet is described using a ring doublet as an image within the droplet. The ring-doublet radius is related to We. Gas potential flow results are presented and compared using both the exact analytical solution and a perturbation analysis based on the square root of We. The perturbation analysis provides a lower computational cost. Three analyses for local curvature, liquid circulation, and gas potential flow are matched to yield the velocity and pressure fields. The appropriate radius for the image ring doublet is matched to the square root of We. Liquid-phase stream function, two velocity components in each fluid, and gas potential field are predicted. S Some comments on droplet drag are presented.
