DNS of ethanol droplet impact onto a smooth surface

In this work, we studied the ethanol droplet spreading process and its dependence on the droplet Weber and Reynolds numbers. We investigated the spreading factor β [1], a critical parameter for characterizing droplet dynamics upon impact, for ethanol droplets over a Weber number range from 35 to 315, using Direct Numerical Simulation (DNS). Subsequently, the DNS results are validated against established empirical correlations. The spreading factor is then studied and compared for ethanol and water droplets. The study employs a Computational Fluid Dynamics (CFD) framework to simulate the impact process, solving the incompressible Navier-Stokes equations using the Finite-Volume method. The gas–liquid interface is defined using the Volume-of-Fluid (VOF) method [2], and the Piecewise Linear Interface Calculation (PLIC) method [3] is employed for interface reconstruction. The DNS tool Free Surface 3D [4] (FS3D), an in-house code at the Institute of Aerospace Thermodynamics, University of Stuttgart, is utilized.