scholarly journals Radial Transport Along the Human Acinar Tree

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
F. S. Henry ◽  
A. Tsuda
Keyword(s):  
Numerical Model ◽  
Entrance Region ◽  
Submicron Particles ◽  
Chaotic Mixing ◽  
Lateral Transport ◽  
Radial Transport ◽  
Intrinsic Motion

A numerical model of an expanding asymmetric alveolated duct was developed and used to investigate lateral transport between the central acinar channel and the surrounding alveoli along the acinar tree. Our results indicate that some degree of recirculation occurs in all but the terminal generations. We found that the rate of diffusional transport of axial momentum from the duct to the alveolus was by far the largest contributor to the resulting momentum in the alveolar flow but that the magnitude of the axial momentum is critical in determining the nature of the flow in the alveolus. Further, we found that alveolar flow rotation, and by implication chaotic mixing, is strongest in the entrance generations. We also found that the expanding alveolus provides a pathway by which particles with little intrinsic motion can enter the alveoli. Thus, our results offer a possible explanation for why submicron particles deposit preferentially in the acinar-entrance region.

Deposition of Submicron Particles by Chaotic Mixing in the Pulmonary Acinus

2021 ◽  
pp. 145-161
Author(s):  
Akira Tsuda ◽  
Frank S. Henry
Keyword(s):  
Fluid Particle ◽  
Submicron Particles ◽  
Chaotic Mixing ◽  
Breathing Frequency ◽  
Particle Trajectories ◽  
Recirculating Flow ◽  
Pulmonary Acinus ◽  
Inhaled Particles ◽  
Hamiltonian Chaos ◽  
Qualitative Changes

In this review, the authors outline the evidence that emerged some 30 years ago that the mechanisms thought responsible for the deposition of submicron particles in the respiratory region of the lung were inadequate to explain the measured rate of deposition. They then discuss the background and theory of what is believed to be the missing mechanism, namely chaotic mixing. Specifically, they outline how that the recirculating flow in the alveoli has a range of frequencies of oscillation and some of these resonate with the breathing frequency. If the system is perturbed, the resonating frequencies break into chaos, and they discuss a number of practical ways in which the system can be disturbed. The perturbation of fluid particle trajectories results in Hamiltonian chaos, which produces qualitative changes in those trajectories. They end the review with a discussion of the effects of chaotic mixing on the deposition of inhaled particles in the respiratory region of the lung.

HREM observation of NiO growth on submicron spheres of pure nickel

1989 ◽  
Vol 47 ◽  
pp. 548-549
Author(s):  
C.M. Teng ◽  
T.F. Kelly ◽  
J.P. Zhang ◽  
H.M. Lin ◽  
Y.W. Kim
Keyword(s):  
Nickel Oxide ◽  
Grain Boundaries ◽  
Pure Nickel ◽  
Submicron Particles ◽  
Crystal Formation ◽  
Nickel Wire ◽  
Liquid Droplets ◽  
Oxide Interface ◽  
Nickel Chromium ◽  
Chromium Alloys

Spherical submicron particles of materials produced by electrohydrodynamic (EHD) atomization have been used to study a variety of materials processes including nucleation of alternative crystallization phases in iron-nickel and nickel-chromium alloys, amorphous solidification in submicron droplets of pure metals, and quasi-crystal formation in nickel-chromium alloys. Some experiments on pure nickel, nickel oxide single crystals, the nickel/nickel(II) oxide interface, and grain boundaries in nickel monoxide have been performed by STEM. For these latter studies, HREM is the most direct approach to obtain particle crystal structures at the atomic level. Grain boundaries in nickel oxide have also been investigated by HREM. In this paper, we present preliminary results of HREM observations of NiO growth on submicron spheres of pure nickel.Small particles of pure nickel were prepared by EHD atomization. For the study of pure nickel, 0.5 mm diameter pure nickel wire (99.9975%) is sprayed directly in the EHD process. The liquid droplets solidify in free-flight through a vacuum chamber operated at about 10-7 torr.

NUMERICAL MODEL TO SIMULATE THE EROSION ON THE SLOPE DUE TO OVERTOPPING

2010 ◽  
Vol 13 (3) ◽  
pp. 78-87
Author(s):  
Hoai Cong Huynh
Keyword(s):  
Numerical Model ◽  
Flow Model ◽  
Bed Load ◽  
Experiment Data ◽  
Step Method ◽  
Morphological Model ◽  
Load Transport ◽  
Bed Load Transport ◽  
The Finite Difference Method ◽  
Good Agreement

The numerical model is developed consisting of a 1D flow model and the morphological model to simulate the erosion due to the water overtopping. The step method is applied to solve the water surface on the slope and the finite difference method of the modified Lax Scheme is applied for bed change equation. The Meyer-Peter and Muller formulae is used to determine the bed load transport rate. The model is calibrated and verified based on the data in experiment. It is found that the computed results and experiment data are good agreement.

A numerical model to verify the communication between Gari and Peccia springs (Cassino, Central Italy)

2015 ◽  
Vol 35 ◽  
pp. 268-271
Author(s):  
Michele Saroli ◽  
Michele Lancia ◽  
Marco Petitta ◽  
Gabriele Scarascia Mugnozza
Keyword(s):  
Numerical Model ◽  
Central Italy
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