Thermodynamics of droplets under extreme ambient conditions by molecular simulation

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The thermodynamic properties of fluids play a central role in the investigation and description of droplet dynamics under extreme ambient conditions. In contrast to phenomenological models, molecular modeling and simulation has a sound physical basis and is therefore well suited for predictions of such properties under extreme conditions. After setting up molecular force field models for the relevant substances and studying their fluid interface properties under equilibrium conditions in the first funding period, non-equilibrium processes during evaporation are in the focus of this project phase. Thereby, mass transfer depending on driving gradients of temperature, pressure and chemical potential are sampled and compared to classical transport models. Evaporation processes across planar as well as strongly curved interfaces are simulated by massively-parallel molecular dynamics. Extreme conditions, i.e. being close to criticality, are of particular interest. The simulations will be carried out under stationary, quasi-stationary and instationary boundary conditions, which will allow for the identification of methodological advantages and disadvantages, depending on the scenario. Next to the evaporation of pure real fluids, such as oxygen, acetone and water, also their mixtures will be studied. Moreover, model systems will be considered that can be defined such that assumptions on "ideality", commonly made in classical transport models, are strictly fulfilled.