Numerical Simulation of Single-Droplet Dynamics, Vaporization, and Heat Transfer from Impingement onto Static and Vibrating Surfaces

Abstract

A numerical study is presented to examine the behavior of a single liquid droplet initially passing through air or steam, followed by impingement onto a static or vibrating surface. The fluid dynamic equations are solved using the Volume of Fluid method, which includes both viscous and surface tension effects, and the possibility of droplet evaporation when the impact surface is hot. Initially, dynamic behavior is examined for isothermal impingement of a droplet moving through air, first without and then with boundary vibration. Isothermal simulations are used to establish how droplet rebound conditions and the time interval between initial contact to detachment vary with droplet diameter for droplet impingement onto a stationary boundary. Heat transfer is then assessed for a liquid droplet initially at saturation temperature passing through steam, followed by contact with a hot vibrating boundary, in which droplet evaporation commences. The paper shows that, for droplet impingement onto a static boundary, the minimum impact velocity for rebound reduces linearly with droplet diameter, whereas the time interval between initial contact and detachment appears to increase linearly with droplet diameter. With the introduction of a vibrating surface, the minimum relative impact velocity for isothermal rebound is found to be higher than the minimum impact velocity for static boundary droplet rebound. For impingement onto a hot surface, in which droplet evaporation commences, it is shown that large-amplitude surface vibration reduces heat transfer, whereas low-amplitude high-frequency vibration appears to increase heat transfer.

Archive of Mechanical Engineering

“…ANSYS Fluent software is used to investigate the freefall droplet characteristics and its impact on the solid and liquid surface. In a very recent research, Thalackottore Jose and Dunne [63] carried out numerical simulation in ANSYS Fluent software in a 2D model to investigate the droplet impingement on a flat surface rather than a 3D model and obtained a considerable conformity with experimental results. It is reported by [62] that the overall deformation of the droplet trend is matched very well with the experimental and analytical results in 2D simulation instead of the 3D model which requires a very high computational cost.…”

Process Optimization for Manufacturing Functional Nanosurfaces by Roll-to-Roll Nanoimprint Lithography

“…We use four levels of adaptive mesh refinement for each time step during our simulations. The mesh utilized in the simulations is 30 × 30 nm, which was chosen as a compromise between computing time and accuracy [ 17 , 18 , 19 ].…”

Numerical Analysis of Convective Mass Transfer during Multi-Droplet Impingement on a Structured Surface in the Presence of an Adhered Liquid Film—An Application to Spray Etching of PCBs

“…The characterization of mass transfer during multi-droplet impingement in general, and spray etching in particular, requires the accurate tracking of the inherent flow conditions. Numerical modelling of single and multiple droplet impingement is frequently based on the Volume of Fluid (VOF) method [1,[16][17][18][19][20][21][22][23]. Further methods are the Level Set (LS) method [24], combinations of the Level Set and the VOF method (CLSVOF) [25] as well as the Lattice Boltzmann (LB) methods [26].…”

“…The tendency to film rupture decreased with increasing viscosity of the fluid. Thalackottore Jose and Dunne [16] examined the impingement of single droplets onto static and vibrating surfaces. Guggilla et al [17] published a numerical study of two droplets impinging consecutively onto a flat heated wall, focusing on film and heat transfer dynamics.…”