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Mohammad Yeasin

Publications and source records attributed to Mohammad Yeasin.

3 recordsLinked to original sources

Computational assessment of incremental pyriform aperture enlargement in plastic surgery: effect on inhaled nasal airflow

Background. The pyriform aperture is a critical anterior bony constriction governing nasal airflow and is clinically relevant to both functional and aesthetic nasal surgery, yet the degree of pyriform aperture enlargement (PAE) needed to capture its aerodynamic benefit is undefined. This study employs high-fidelity computational fluid dynamics (CFD) to quantify the aerodynamic effects of progressive PAE and identify a threshold beyond which further enlargement yields minimal benefit. Methods. A CT-derived three-dimensional nasal airway model was digitally modified to produce baseline, 5%, 10%, 15%, and 20% increases in pyriform aperture cross-sectional area. Pressure-driven large-eddy simulations (LES) were performed at a fixed transnasal pressure difference of 11.25 Pa to quantify changes in inspiratory flow rate, total airway resistance, and local airflow characteristics. Results. Progressive PAE monotonically increased inspiratory flow from 15.063 to 15.252 L/min (approximately 1.25%) and reduced airway resistance from 0.6138 to 0.6028 Pa.min/L (approximately 1.80%). The aerodynamic response was strongly nonlinear, with the greatest improvement occurring between 10% and 15% enlargement. Increasing the aperture from 15% to 20% produced negligible additional improvement. Conclusions. PAE improves nasal airflow by reducing the resistance imposed by the anterior bony constriction. In the anatomical model investigated, approximately 15% area enlargement represented an efficient aerodynamic threshold, after which the dominant resistance shifted toward downstream nasal structures and further enlargement produced little additional benefit. These findings support a conservative, anatomy-dependent approach to PAE and warrant validation across a broader range of patient-specific geometries.

physics.med-ph↗

Mechanics-guided parametric modeling of intranasal spray devices and formulations for targeted drug delivery to the nasopharynx

Improving the efficacy of nasal sprays by enhancing targeted drug delivery to intra-airway tissue sites prone to infection onset is hypothesized to be achievable through an optimization of key device and formulation parameters, such as the sprayed droplet sizes, spray cone angle, and formulation density. This study focuses on the nasopharynx, a primary locus of early viral entry, as the optimal target for intranasal drug delivery. 3D anatomical upper airway geometries reconstructed from high-resolution computed tomography scans were used to numerically evaluate a cone injection approach, with inert particles mimicking the motion of sprayed droplets within an underlying inhaled airflow field. We have considered monodisperse sprayed particles sized between 10 to 50 microns, six densities ranging from 1.0 to 1.5 g/ml for the constituent formulation, and twelve plume angles spanning 1 to 70 degrees subtended by the spray jet at the nozzle position. Large Eddy Simulation-based modeling of the inhaled airflow physics within the anatomical domains was coupled with a Lagrangian particle-tracking framework to derive the drug deposition trend at the nasopharynx. The resulting globally averaged deposition contour map, obtained by interpolating the outcomes for the discrete test parameters, revealed that nasopharyngeal deposition peaked for droplet sizes 25 to 45 microns and plume angles equal to or less than 30 degrees. In addition, the formulation density of 1.0 g/ml yielded the highest mean deposition rate, over the tested range of sprayed particle sizes and plume angles. The findings were experimentally validated through representative physical spray tests conducted in a 3D-printed replica of one of the test geometries and collectively demonstrate that rational optimization of the intranasal spray design is attainable, with substantial enhancement of targeted drug delivery to the nasopharynx.

physics.med-ph↗

Modeling the effect of vorticity on inhaled transport in the upper airway

Localized vortices can have significant influence on transport of inhaled particles through the upper respiratory tract. These vortices have complex three-dimensional structure with details dependent on the anatomical geometry. Using a highly simplified model, we demonstrate that changes in transport characteristics with geometric distortion can be estimated by accounting merely for the net strength and location of the vorticity in a two-dimensional projection. Test cases consider 30 L/min inhaled airflow containing suspended spherical water droplets from 1 micrometer to 30 micrometers in diameter through (1) a healthy upper respiratory tract and (2) a distorted variation mimicking a glottic tumor. The reduced-order model approximates the system by a two-dimensional potential flow with embedded point vortices having features derived from Large Eddy Simulations of inhaled airflow through anatomically realistic, tomography-based, three-dimensional tracts. The effects of vorticity and particle size on changes in particle transport are shown to be consistent between the reduced-order model and the full-scale simulations.

physics.flu-dyn↗