Model studies on motion of respiratory droplets driven through a face mask

Abstract

Face masks are used to intercept respiratory droplets to prevent spreading of air-borne diseases. Designing face masks with better efficiency needs microscopic understanding on how respiratory droplets move through a mask. Here we study a simple model on the interception of droplets by a face mask. The mask is treated as a polymeric network in an asymmetric confinement, while the droplet is taken as a micrometer sized tracer colloidal particle, subject to driving force that mimics the breathing. We study numerically, using the Langevin dynamics, the tracer particle permeation through the polymeric network. We show that the permeation is an activated process following an Arrhenius dependence on temperature. The potential energy profile responsible for the activation process increases with tracer size, tracer bead interaction, network rigidity and decreases with the driving force and confinement length. A deeper energy barrier led to better efficiency to intercept the tracer particles of a given size in the presence of driving force at room temperature. Our studies may help to design mask with better efficiency.

Transport of particles through RO membrane in steady state condition

“…We choose the interaction parameters such that the polymeric network is uniformly spread throughout the gap between two walls. We characterize interpenetrating network of identical polymeric strands by the inter‐strand correlation function C ( r ) [23] where r is the cross‐strand bead‐bead distance. The C(r) data in Figure 2(a) shows a sharp first peak at $${r = 2}$$ , equal to the polymeric bead diameter.…”

“…These works establish emergence of non‐linearity in flux‐force relation for large driving force [22] and the solute selectivity of system can be tuned by a small change of the external force [22] . In a recent work, we have shown that the permeation of particles driven through an interpenetrating polymeric network is an activated process, the activation barrier being controlled by several parameters, like the driving force, network‐particle interaction and polymer density [23] …”

“…[22] In a recent work, we have shown that the permeation of particles driven through an interpenetrating polymeric network is an activated process, the activation barrier being controlled by several parameters, like the driving force, network-particle interaction and polymer density. [23] There is yet no attempt addressing the microscopic basis to understand the performance of RO membrane including all the aspects, namely, solvent permeation (P), solute rejection (R) and membrane fouling (F). Here, we investigate a simple microscopic model to study the solvent and solute motion in the steady state through an RO membrane in presence of an external force.…”

“…The membrane is modelled as a network of interpenetrating polymeric strands with two different kinds of beads in a 50 : 50 ratio characterized by different interactions among themselves as in our previous study. [23] The network is stabilized within confinement made of two asymmetric walls, each having favourable interaction with a given type of bead. This mimics the asymmetric interface between organic and aqueous phases in IP.…”

Dynamics of aqueous suspension of short Hyaluronic acid chains near DPPC bilayer

“…To find out the origin of the distinct concentration and chain size dependence of the water dynamics, we consider the organization of the HA chains via the cross-chain radial distribution 44 of HA monomers, g xy (r), where r is the distance in the plane parallel to the bilayer, between the COM of two HA monomers belonging to two distinct chains. Figure 5(a) shows g xy (r) vs r plot for different n HA5 .…”