In this paper, we demonstrate the application of a generalised Fully Lagrangian Approach to the simulation of polydisperse gas-evaporating droplet flows. The paper focuses on the proposed methodology for modelling the dispersed phase, droplets, in both steady and transient cases. To account for polydispersity, the set of Lagrangian variables is extended to include the droplet size, and the droplet size distribution function is introduced to the droplet parameter set. According to the Lagrangian approach, all the droplet parameters, including the distribution function, are found along the droplet trajectories. An interpolation scheme to convert droplet parameter fields from a Lagrangian to an Eulerian framework for visualising droplet distribution is proposed. The developed methodology was applied to simple 1D and 2D stationary cases for verification, after which it was incorporated into OpenFOAM to simulate steady and periodic flows around a cylinder. In the case of a steady flow, a region devoid of droplets is formed behind the cylinder. From the droplet distribution plots, it was observed that small and medium sized droplets reach a region near to the axis of the symmetry of the flow. In the case of periodic flow, the analysis of droplet distribution is based on instantaneous pictures of the droplet parameters rather than their values along droplet trajectories. In this flow, strongly influenced by vortices, a strong droplet segregation is shown; at various locations one can see a full droplet size spectrum, only small or large droplets, and/or droplets from a narrow size interval. In all cases, the effect of the evaporation is to decrease the maximum value of the droplet distribution function shifted towards smaller-sized droplets.

在本文中，我们展示了广义的完全拉格朗日方法在多分散气体蒸发液滴流模拟中的应用。本文重点介绍了在稳态和瞬态情况下对分散相、液滴进行建模的建议方法。为了说明多分散性，拉格朗日变量集扩展为包括液滴尺寸，并将液滴尺寸分布函数引入液滴参数集。根据拉格朗日方法，所有液滴参数，包括分布函数，都是沿着液滴轨迹找到的。提出了一种将液滴参数场从拉格朗日公式转换为欧拉框架的插值方案，用于可视化液滴分布。将开发的方法应用于简单的一维和二维静止情况进行验证，然后将其合并到 OpenFOAM 中以模拟圆柱周围的稳定和周期性流动。在稳定流动的情况下，在圆柱体后面形成没有液滴的区域。从液滴分布图中，观察到中小尺寸液滴到达靠近流动对称轴的区域。在周期性流动的情况下，液滴分布的分析基于液滴参数的瞬时图像，而不是它们沿液滴轨迹的值。在这个流动中，受到涡流的强烈影响，显示出强烈的液滴分离；在不同的位置，人们可以看到完整的液滴尺寸谱，只有小的或大的液滴，和/或来自狭窄尺寸区间的液滴。在所有情况下，