arXiv subjects

Maxim Yurkin

Publications and source records attributed to Maxim Yurkin.

3 recordsLinked to original sources

arXiv2026

An Innovative Computational Fluid Dynamics Discrete Dipole Approximation (CFD-DDA) Platform for Predicting Airborne Virus-in-Saliva Disinfection by Ultraviolet Irradiation

All published models of ultraviolet (UV) inactivation of airborne viruses in saliva droplets have neglected UV light scattering. To the best of our knowledge, this work presents the first Computational Fluid Dynamics-Discrete Dipole Approximation (CFD-DDA) platform for investigating the physical mechanisms governing UV disinfection of virus-laden airborne saliva droplets. The DDA solver predicts UV light scattering by both spherical and irregularly shaped saliva droplets, while the CFD solver predicts droplet evaporation and transport in airflow. By coupling the DDA and CFD solvers, we demonstrate that infected saliva droplets, whether spherical or irregularly shaped due to evaporation, experience highly non-uniform UV light scattering that significantly affects virus inactivation and cannot be neglected. This phenomenon has not previously been investigated within a fully three-dimensional framework. The coupled Euler-Lagrange CFD-DDA model further quantifies the effects of (i) the initial droplet size distribution and concentration, (ii) airflow rate, and (iii) droplet interactions with the surrounding airflow and bounding walls on the total number of surviving coronavirus copies $N_s$, assuming a virion diameter of 100 nm, an air temperature of 21 $^{\circ}$C, and a relative humidity of 65%. Based on the DDA results, a new virus inactivation model, referred to as the Dbouk-Yurkin law, is proposed. This model extends the classical Chick-Watson law by explicitly accounting for UV light scattering in both spherical and non-spherical airborne saliva droplets. The proposed three-dimensional CFD-DDA platform provides a powerful framework for improving the understanding of UV-based airborne virus disinfection and for optimizing the design and performance of UV air purification systems.

physics.flu-dyn↗

arXiv2025

Extension of interferometric particle imaging to small ice-crystal sizes using the Discrete Dipole Approximation

Interferometric Particle Imaging (IPI) is a powerful technique to characterize aerosol particles, which so far has been applied only to particles larger than about 100 wavelengths. We extend its applicability to smaller ice crystals, combining rigorous modelling of particle shapes with the Phase Field Modelling and light-scattering simulations with the Discrete Dipole Approximation (DDA). Even for particles with the largest dimension of 11.5 wavelengths (and the smallest one comparable to the wavelength), the 2D Fourier transform of the interferometric image remains linked to the 2D autocorrelation of the particle shape at various viewing angles, validating the general measurement principle. However, the sensor must necessarily have wide viewing angle, which complicates interpretation of apparent particle shape, when such particles are observed from the edge. IPI is, thus, shown to be a powerful optical technology for characterizing ice particles down to a few micrometers in the atmosphere. Meanwhile, DDA is a versatile method for such synthetic experiments and can further supply large datasets for development of various inversion methods.

physics.optics↗

arXiv2025

Microwave scattering by rough polyhedral particles on a surface

The electromagnetic (EM) scattering by non-symmetric wavelength-scale particles on a planar surface has numerous applications in the remote sensing of planetary bodies, both in planetary and geo-sciences. We conduct numerical simulations of EM scattering by rough polyhedral particles (with 12 or 20 faces) using the discrete-dipole approximation and contrast the results to that of spheres. The particles have permittivities corresponding to common minerals in the microwave regime ($\epsilon_r=4.7 + 0.016$i and $7.8 + 0.09$i), and a size-frequency distribution (SFD) consistent with the observed scattering properties (power-law distribution of size parameters between 0.5 and 8 with an index from $-2.5$ to $-3.5$). The assumed substrate permittivity $2.4 + 0.012$i corresponds to a powdered regolith. We present what roles the particle roundness, permittivity, and SFD for a realistic range of parameters play in the EM scattering properties as a function of incidence angle with a focus on backscattering in microwave-remote-sensing applications. The particle roundness and SFD have a clearly observable effect on the polarimetric properties, while the role of permittivity is relatively minor (in the studied range). Among various backscattering observables, the circular polarization ratio is the least sensitive to the decrease of the upper boundary (down to a size parameter of 3) and the index of the SFD.

astro-ph.EP↗