Numerical Assessment of Particle Collection Efficiency of an Adaptor Connecting a Viable Virus Aerosol Sampler and a Point-of-Care Detector

AMIN SHIRKHANI, Sripriya Nannu Shankar, Carlos Mazanas, Z. Hugh Fan, Chang-Yu Wu, University of Florida

     Abstract Number: 641
     Working Group: Instrumentation and Methods

Abstract
Collection and on-the-spot detection of respiratory virus aerosols allow quick actions to minimize exposure. In this study, we carried out computational fluid dynamics (CFD) simulations of aerosol flows in an adaptor, which facilitates the integration of the viable virus aerosol sampler (VIVAS) and a valve-enabled lysis, paper-based RNA enrichment, RNA amplification device (VLEAD), to numerically investigate its collection capability. This adaptor, when attached to VIVAS during sampling, functions as a collector. After sampling, the collection medium containing virus particles is transferred directly to VLEAD with the help of a ball valve located at the bottom of the adaptor, for point-of-care analysis. Ansys FLUENT (Fluent 2021 R2) was used to 1) generate tetrahedron mesh (with approximately 1.2 million elements) and 2) study particle trajectory and impaction on liquid collection medium. In our CFD model, we used steady-state, pressure-based, isothermal, laminar air flow with a velocity of 0.5 m/s at the inlets (eight cylindrical tubes) under ambient operating conditions. Lagrangian approach was utilized for particle tracking, and “trap” condition was set for all the surfaces except for inlets and outlets, which are defined as “escape”. Monodisperse water droplets of varied sizes uniformly distributed at the inlet of the tubes were simulated for their flow through the tubes, and then toward the collection medium surface, through 24 nozzles. Droplets' trajectories were calculated until they left the domain (escaped from the outlet) or trapped on the liquid surface. Based on the number of particles trapped on the surface of the collection medium over the total number of particles at the inlet, physical collection efficiencies of 95.8%, 98.1%, and 100% were recorded for droplet sizes of 0.1, 1, and 5 µm, respectively. Comparison with experimental data to validate these results will be reported at the conference