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

Abstract

When a droplet impacts a fabric mesh at a sufficiently high impact velocity, it not only spreads over the fabric but also penetrates 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 in 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.

Modulating the surface and mechanical properties of textile by oil-in-water emulsion design

“…Recent study 54 suggests a quantitative correlation between droplet spreading ratio, impact velocity, and uid properties by interpolating between the capillary regime (f W e 1/2 ) and viscous regime (f R e 1/5…”

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“…Hence, an additional criterion based on droplet surface tension is derived in this work, which suggests that the liquid droplet can penetrate through the fabric only when the resisting capillary pressure inside the fabric pores (∼4 σ / ) exceeds the impact dynamic pressure (∼ ρV 2 ) that the droplet exerts on the fabric. 51 Hence, the droplet can only penetrate a porous surface or mesh when the dynamic pressure of the droplet is high enough to overcome the capillary pressure of the pores, as shown in the following equations: where ρ is liquid density, σ is the surface tension between the water–air interface, V is impact velocity, ϵ is pore size, and We is the weber number. The calculated values of are tabulated in Table II .…”

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“…They also concluded that the spherical shape of the droplet on the textile does not change when it interacts with porous substrates with a pore size from 100-300 µm in short time periods. Reference [165] analyzed the penetration of droplets in polyester fabric pores with and without an underlying substrate. The spreading ratio of water-glycerol droplets on the substrate is different with and without the underlying substrate because of the volume loss of the liquid [165].…”

“…Reference [165] analyzed the penetration of droplets in polyester fabric pores with and without an underlying substrate. The spreading ratio of water-glycerol droplets on the substrate is different with and without the underlying substrate because of the volume loss of the liquid [165].…”