000			02814nam a22001577a 4500
082			_a621
100			_aSiddiqui, Hadia Alam _9131560
245			_aMicroplastic Behavior in Idealistic Exhalation Dynamics: Exploring Shape, Density, and Diameter Effects Using CFD / _cHadia Alam Siddiqui
264			_aIslamabad : _bSMME- NUST; _c2025.
300			_a60p. _bSoft Copy _c30cm
500			_aMicroplastics are now ubiquitous contaminants in the atmosphere which have raised substantial public health issues. While extensive research has focused on particle deposition during inhalation, the exhalation phase, a critical component of the complete respiratory cycle, remains comparatively less explored. The study aims at addressing this research gap by conducting a comprehensive computational investigation into the deposition dynamics of microplastic particles during exhalation within an idealized human tracheobronchial airway model from generations G3–G6. A three-dimensional airway geometry was constructed via Weibel's morphometric data, adjusted for a 50-year-old adult. Computational Fluid Dynamics (CFD) simulations are performed using the Reynolds-Averaged Navier-Stokes (RANS) approach with the (SST) 𝑘-𝜔 turbulence model. The Discrete Phase Model (DPM) was employed to track trajectories of spherical microplastic particles 2-22 µm under four exhalation flow rates 125, 300, 500, and 1000 ml/s, representing varying breathing intensities from resting to heavy exercise. The results demonstrate an inverse relationship between exhalation flow rate and overall deposition efficiency (DE). Lower flow rates resulted in the highest DE, as particles had greater residence time for gravitational sedimentation and were less influenced by turbulent dispersion. In contrast, higher flow rates generated significant turbulent kinetic energy, which enhanced particle mixing and reduced net deposition. Furthermore, deposition was strongly governed by inertial impaction, as evidenced by a positive correlation with the Stokes number. Spatial analysis revealed that while high flow rates created intense deposition hotspots at major bifurcations, the cumulative particle deposition isXIV significantly lower than at gentler flow rates, where deposition is more widespread. This study concludes that gentle exhalation poses a greater risk for microplastic retention in the lower bronchial airways. The findings challenge the assumption that higher airflow invariably leads to increased deposition and provide crucial insights into the mechanisms of particle exposure during the exhalation phase.
650			_aMS Mechanical Engineering
700			_aSupervisor : Dr. Ammar Tariq _9126970
856			_uhttp://10.250.8.41:8080/xmlui/handle/123456789/55981
942			_2ddc _cTHE
999			_c615225 _d615225