Droplet Impact on Suspended Metallic Meshes: Effects of Wettability, Reynolds and Weber Numbers

Abstract

Liquid penetration analysis in porous media is of great importance in a wide range of applications such as ink jet printing technology, painting and textile design. This article presents an investigation of droplet impingement onto metallic meshes, aiming to provide insights by identifying and quantifying impact characteristics that are difficult to measure experimentally. For this purpose, an enhanced Volume-Of-Fluid (VOF) numerical simulation framework is utilised, previously developed in the general context of the OpenFOAM CFD Toolbox. Droplet impacts on metallic meshes are performed both experimentally and numerically with satisfactory degree of agreement. From the experimental investigation three main outcomes are observed—deposition, partial imbibition, and penetration. The penetration into suspended meshes leads to spectacular multiple jetting below the mesh. A higher amount of liquid penetration is linked to higher impact velocity, lower viscosity and larger pore size dimension. An estimation of the liquid penetration is given in order to evaluate the impregnation properties of the meshes. From the parametric analysis it is shown that liquid viscosity affects the adhesion characteristics of the drops significantly, whereas droplet break-up after the impact is mostly controlled by surface tension. Additionally, wettability characteristics are found to play an important role in both liquid penetration and droplet break-up below the mesh.

On secondary atomization and blockage of surrogate cough droplets in single- and multilayer face masks

“…Thus, the droplet penetration depends on the impact velocity, thickness, and pore size of the mask, while it is independent of the diameter of the impacting droplet provided the droplet diameter is much larger than the pore size of the mask ( D i >> ε) ( 33 , 39 ). For validating the applicability of these criteria, experiments are conducted with different droplet impact velocities of 2 to 10 m/s while maintaining the same droplet diameter for all cases.…”

Droplet impacting a superhydrophobic mesh array: Effect of liquid properties

“…Most of the existing researchers have adopted experiment methodologies [9,20] which provide qualitative rather than quantitative results due to experimental limitations [7][8][9][10][11]. Important physical insights into complex two-phase flow regarding the velocity distribution within the liquid and the energy evolution in the dynamic process are currently inaccessible by experimental techniques.…”

“…In 2019, Wang et al [21] used a many-body dissipative particle dynamics (MDPD) method to simulate water droplet fragmentation after impacting on mesh screens and determined the droplet ejection angle and the penetrated mass. More recently, Vontas et al [20] adopted the volume-of-fluid (VOF) method to investigate droplet impact on various mesh screens.…”

“…However, the influence of droplet properties has not been systematically researched [9]. One exception was the study of Vontas et al [20], which tested a water, acetone, and glycerol mixed droplet impacting a mesh. However, the dimensionless Ohnesorge number in their study was less than the critical value 0.018 [20,22] below which the viscosity effect is negligible in the droplet dynamics.…”

“…One exception was the study of Vontas et al [20], which tested a water, acetone, and glycerol mixed droplet impacting a mesh. However, the dimensionless Ohnesorge number in their study was less than the critical value 0.018 [20,22] below which the viscosity effect is negligible in the droplet dynamics. Therefore a knowledge gap still exists in this configuration, especially for the high-viscosity droplet.…”