Deposition fraction of ellipsoidal fibers in the human nasal cavity- Influence of non-creeping formulation of hydrodynamic forces and torques

Abstract In this study, deposition fraction of ellipsoidal particles in a 3D-Model of the nasal cavity (right airway) of a 24-year-old healthy woman was simulated for laminar and turbulent inhalation flow rates. The geometry used included the main nasal cavity from the nostril to the beginning of nasopharynx and was constructed in the Ansys-ICEM software from a CT scan image. The numerical simulations of governing equations were obtained using the Ansys-Fluent software. The mean airflow was assumed to be incompressible and steady. For turbulence modeling, the Realizable k-ε model was employed and the Lagrangian trajectory analysis method was used for particle tracking. For evaluating the ellipsoidal particle motions, several user-defined functions (UDFs) were developed and linked to the discrete phase model of the Ansys-Fluent code. The developed UDFs solve for the coupled translational and rotational equations of motion for ellipsoidal fibers and also accounts for the stochastic modeling of turbulence velocity fluctuations. The hydrodynamic forces and torques were calculated based on the non-creeping formulations for various ellipsoidal fibers. Laminar flow condition was assumed for breathing rate of 5.0 lit/min for the rest or light physical activities and turbulent flow condition was assumed for airflow rate of 20 lit/min for high physical activities. To investigate the dispersion and deposition of particles in the model of the human nasal cavity, various fibers with a semi-minor axis of 1, 3, 5 and 10 μm and various aspect ratios were considered. Using the non-creeping flow formulation for hydrodynamic forces and torques, the simulation results showed slight differences in the total deposition fraction of ellipsoidal fibers compared with the corresponding creeping flow model. Small fibers deposit roughly uniformly in the nasal cavity with no hotspot region. For the large inertial fibers, however, the nasal valve is a hot spot region, where the deposition rate reaches to its peak.

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Deposition fraction of ellipsoidal fibers in a model of human nasal cavity for laminar and turbulent flows

Journal of Aerosol Science ◽

10.1016/j.jaerosci.2017.07.008 ◽

2017 ◽

Vol 113 ◽

pp. 52-70 ◽

Cited By ~ 8

Author(s):

M.M. Tavakol ◽

E. Ghahramani ◽

O. Abouali ◽

M. Yaghoubi ◽

G. Ahmadi

Keyword(s):

Nasal Cavity ◽

Turbulent Flows ◽

Deposition Fraction ◽

Laminar And Turbulent Flows

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Deposition Fraction of Ellipsoidal Particles in a Fully Developed Laminar Pipe Flow: Application of New Correlations for Hydrodynamic Forces and Torques

Volume 1D, Symposia: Transport Phenomena in Mixing; Turbulent Flows; Urban Fluid Mechanics; Fluid Dynamic Behavior of Complex Particles; Analysis of Elementary Processes in Dispersed Multiphase Flows; Multiphase Flow With Heat/Mass Transfer in Process Technology; Fluid Mechanics of Aircraft and Rocket Emissions and Their Environmental Impacts; High Performance CFD Computation; Performance of Multiphase Flow Systems; Wind Energy; Uncertainty Quantification in Flow Measurements and Simulations ◽

10.1115/fedsm2014-21634 ◽

2014 ◽

Author(s):

Mohammad Mehdi Tavakol ◽

Omid Abouali ◽

Mahmood Yaghoubi ◽

Goodarz Ahmadi

Keyword(s):

Pipe Flow ◽

Deposition Efficiency ◽

Hydrodynamic Forces ◽

Transport Processes ◽

Creeping Flow ◽

Spherical Particles ◽

Low Reynolds Number Flows ◽

Ellipsoidal Particles ◽

Deposition Fraction ◽

Laminar Pipe Flow

The physics of transport, deposition, detachment and reentrainment re-entrainment of particles suspended in a fluid are of great interests in many practical fluid engineering problems. For spherical particles, analysis of their translational motions is sufficient for a complete description of their transport processes. Prediction of transport and deposition of non-spherical particles, however, is more complicated due to the coupling of particle translational and rotational motions. Most studies related to dispersion of ellipsoidal particles used the traditional creeping flow formulations for hydrodynamic forces and torques. These formulations are valid for very low Reynolds number flows. In this study, dispersion and deposition of ellipsoidal particles in a fully developed laminar pipe flow are analyzed numerically using new correlations for hydrodynamic forces and torques. The deposition efficiency of the ellipsoidal particles in laminar pipe flow are calculated and the results are compared with other theoretical and numerical studies and good agreement is observed.

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Detailed Analysis of Fiber Motion in Human Nasal Airways

10.1115/fedsm2021-65576 ◽

2021 ◽

Author(s):

Jiang Li ◽

J. W. Ma ◽

J. Y. Tu ◽

L. Tian ◽

G. Ahmadi

Keyword(s):

Experimental Data ◽

Nasal Cavity ◽

Particle Transport ◽

Particle Deposition ◽

Deposition Efficiency ◽

Spherical Particles ◽

Nasal Airways ◽

Deposition Fraction ◽

Simulation Results ◽

Fiber Transport

Abstract Information on the fiber particle transport and deposition in human nasal airways is of great importance in inhalation toxicology study. Due to the complex interactions between the inhaled aerosol particles and human respiratory airways, the particles’ toxicity varies with their chemical composition, size, and shape. In the earlier computational study of fiber particle motion in human nasal cavities, overall deposition efficiency curves were evaluated and compared with the available experimental data. The majority of investigations were on micron-scale fiber particles, and the observed deposition fraction is strongly affected by fiber inertial impaction and the geometry of the cavity. The fiber characterization by its equivalent spheres is still not entirely fully understood. Limited existing evidence indicated that, when benchmarked by the impaction parameter, spherical particles tend to have a higher deposition fraction than that of the elongated fiber particles in the nasal cavity. More data is needed to elaborate on these observations and reveal the underlying physics. A more profound understanding of fiber transport in human airways may be obtained by comparing the fibrous particle deposition to that of the spherical particles. In this study, simulations of transport and deposition of elongated particles in a realistic human nasal cavity model for a steady laminar airflow rate were performed. FLUENT 19.2 was used to solve the airflow conditions. The elongated ellipsoidal particle transport and deposition were simulated using the coupled translational and rotational equations of motion. The hydrodynamic drag and torque, shear-induced lift, and gravitational force were included in the analysis. One-way coupling was assumed, and an in-house User Defined Function (UDF) was developed and was implemented into the ANSYS-FLUENT code for analyzing the fiber transport and deposition. The airflow field, the particle deposition efficiency, particle deposition pattern, and single-particle trajectories of fiber and sphere were analyzed and presented. The simulation results were compared with available experimental data and simulation results in the literature.

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A Numerical Investigation of Regional Fiber Deposition in a Realistic Nasal Cavity

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2012-72368 ◽

2012 ◽

Author(s):

Alireza Dastan ◽

Omid Abouali ◽

Goodarz Ahmadi

Keyword(s):

Nasal Cavity ◽

Equations Of Motion ◽

Computer Code ◽

Spherical Particles ◽

Navier Stokes ◽

Continuity Equations ◽

Aspect Ratios ◽

Deposition Fraction ◽

Fiber Deposition ◽

Rotation Motion

In this paper, the motion and deposition of micro fibers in different regions of a realistic human nasal airway were studied using a computational modeling approach. The airflow field in the nasal cavity was simulated by solving the Navier-Stokes and continuity equations. The coupled translational and rotation motion of the fibers were analyzed by a Lagrangian approach assuming one-way coupling. The fibers were assumed to be ellipsoids and a computer code was developed for solving the coupled translational and rotational equations of motion of the ellipsoidal fiber. A large number of fibers were injected at the nostril and the deposition pattern and deposition fraction (DF) of the fibers in different regions of the nasal cavity were evaluated for different breathing rates, various fiber diameters and different fiber aspect ratios. The simulation results for ellipsoidal fibers obtained by solving the coupled translational and rotational equations were compared with those obtained by solving only the translational equations of equivalent spherical particles with a shape factor, which were used in some earlier works.

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