Droplet impact of Newtonian fluids and blood on simple fabrics: effect of fabric pore size and underlying substrate

TL;DR

This study investigates how droplet impact and penetration affect spreading on fabrics, revealing that fabric pore size and substrate presence influence spreading ratios, with blood behaving as a Newtonian fluid during impact.

Contribution

It combines experimental measurements and lattice Boltzmann simulations to analyze droplet spreading and penetration on fabrics, highlighting the role of viscous losses and confirming blood's Newtonian behavior.

Findings

Droplet penetration reduces spreading ratio on fabrics.

Viscous losses inside the droplet increase during spreading.

Blood can be modeled as a Newtonian fluid in impact scenarios.

Abstract

When a droplet impacts a fabric mesh at a sufficiently high impact velocity, it not only spreads over the fabric but also penetrate its pores. To determine the influence of this liquid penetration of the fabric on droplet spreading on thin fabric meshes, we measured the droplet spreading ratio on fabric with and without an underlying substrate using a high-speed camera. For fabrics without a substrate, the droplet spreading ratio is reduced as the fabric penetration by the liquid reduces the droplet volume spreading on top of the fabric. Using entropic lattice Boltzmann simulations, we find that the lower droplet spreading ratio on fabrics, both with and without a substrate, is due to an increase of viscous losses inside the droplet during spreading. Comparing droplet impact of blood with its Newtonian counterpart, we show that for spreading on fabrics, just like on smooth surfaces, blood can be approximated as a Newtonian fluid.