Coalescence of argon droplets with a radius of R=25, 50 and 100 nm was studied with computational fluid dynamics (CFD). The constitutive equations for the CFD simulations were derived from a phase-field model coupled to the Navier-Stokes equations. Therein, the thermodynamics of the fluid were incorporated by an equation of state for the Lennard-Jones truncated and shifted fluid based on perturbation theory (PeTS), along with the influence parameter, expressing the density and density gradient dependent part of a Helmholtz energy functional. Moreover, an expression for the viscosity and the surface tension for adjusting the influence parameter were needed. Surrounded by coexisting vapor, the droplets were initialized with a distance of approximately a single argon molecule diameter. The coalescence process was studied under isothermal conditions at a temperature of T=110 K. To save computational resources, a interface widening approach was used to perform the calculations on a coarser grid, while keeping the correct physics.

Data of the coalescing droplets’ interface contours are stored in .csv files, compressed as .tar.xz archives that can be found in the contour/ subdirectories (Tree view). One .csv file contains the data for a single interface contour described by spatial coordinate pairs x [nm] and r [nm] at the time instance t [ps] indicated by the time stamp in the file name, e.g.: _t000000100.csv => t=100 ps.

The archive "early.tar.xz" contains data for the "early" stages of the coalescence process with fine time resolution (1 ps) and the archive "full.tar.xz" contains data for the "full" process with coarser time resolution (10, 20 and 40 ps for R=25, 50 and 100 nm).

A simple python script to plot coalescing droplets contours from the .csv is provided in the subdirectory python/ (Tree view). It will generate contour plots and save them as .pdf files. Additionally, a sequence of all contours will be created by merging the *.pdf files to a single file.

Extracted from the interface contours, the evolution of the bridge radius r_b [nm] as well as back of drop positions x_bdl [nm] (left) and x_bdr [nm] (right) over time t [ns] can be found in the *_evo.tab files.

All data were stored as .csv files with ',' used as separator character. Although the DaRUS database system converted these files to the .tab format, they can be downloaded in the original file format.

The data set provided for R=100nm was obtained from a simulation employing the interface widening approach with a four times broader interface compared to the true extent under equilibrium conditions. The data provided for R=25 and 50 nm were obtained from simulations without employing the interface widening approach.

Data sets for the droplets with initial radius R=25, 50 and 100 nm are organized in the subdirectories R25nm/, R50nm/ and R100nm/ (Tree view).