CFD Benchmark Tests for Indoor Environmental Problems: Part 4 Air-conditioning Airflows, Residential Kitchen Airflows and Fire-Induced Flow

2017

Indoor environmental quality, e.g. air quality and thermal environments, has a potential impact on residents in indoors. Development of a computer simulated person (CSP) for indoor computational fluid dynamics (CFD) simulation can contribute to the improvement of design and prediction method regarding the interaction between indoor air/thermal environmental factors and human responses. In this study, a CSP integrated with a virtual airway was developed and used to estimate inhalation exposure in an indoor environment. The virtual airway is a numerical respiratory tract model for CFD simulation that reproduces detailed geometry from the nasal/oral cavity to the bronchial tubes by way of the trachea. Physiologically based pharmacokinetic (PBPK)-CFD hybrid analysis is also integrated into the CSP. Through the coupled simulation of PBPK-CFD-CSP analysis, inhalation exposure under steady state conditions where formaldehyde was emitted from floor material was analysed and respiratory tissue doses and their distributions of inhaled contaminants are discussed quantitatively.

Section: Methodsmentioning

confidence: 99%

Numerical prediction of tissue dosimetry in respiratory tract using computer simulated person integrated with physiologically based pharmacokinetic–computational fluid dynamics hybrid analysis

Yoo

2017

“…Furthermore, a grid independence check was executed carefully and elaborately and the minimum mesh size near the wall surface, skewness, and size ratio of adjoining meshes were elaborately designed, especially for the room model with the CSP. 40–43 Concerning the respiratory tract model, we have already reported the grid independence check results and the validation results according to experimental data. 21,29…”

Section: Methodsmentioning

confidence: 99%

First- and second-hand smoke dispersion analysis from e-cigarettes using a computer-simulated person with a respiratory tract model

Kuga

Yoo

et al. 2017

The purpose of this study was to investigate, in the human respiratory tract, the flow patterns and adsorption flux (deposition flux) distributions of volatile organic compounds (VOCs) generated by the use of electronic cigarettes (e-cigarettes) through the application of a three-dimensional computational fluid dynamics (CFD) analysis. Two types of human respiratory tract models, which give detailed respiratory tract geometries were reproduced in this study using computed tomography data, for the CFD analysis of inhalation exposure. Complicated flow patterns, nonuniform distributions of VOC concentrations, and heterogeneous adsorption flux distributions were determined within the human respiratory tract models, and individual specificity was confirmed. The CFD simulation results of adsorption flux distributions on the epithelium tissue surfaces of airways denoted the probability distributions of inhalation exposure in respiratory tracts, and high adsorption flux sites representing ‘hot spots’ were delineated for tissue doses of VOCs generated from smoking e-cigarettes. Furthermore, dispersion and diffusion of VOCs in an indoor environment due to exhalation of the vapour phase of e-cigarette emissions were analysed by using a computer-simulated person with a numerical respiratory tract model through an integrated and contiguous analysis of inhalation and exhalation modes during e-cigarette smoking.

“…The model (Abe-Kondoh-Nagano model) has been adopted for the various types of flow field analysis (from laminar to turbulent) and has confirmed the good prediction accuracy for flow field analysis intended for enclosed spaces. [21][22][23][24] A steady and constant breathing airflow rate was used for the breathing condition as a function of metabolic rate and was set at the end of trachea outlet for each model. The turbulent kinetic energy at the inlet, i.e., at the nostril, was specified with a 10% turbulence intensity.…”

Section: Humanmentioning

confidence: 99%

“…The model (Abe–Kondoh–Nagano model) has been adopted for the various types of flow field analysis (from laminar to turbulent) and has confirmed the good prediction accuracy for flow field analysis intended for enclosed spaces. 21–24…”

Section: Airflow Simulationsmentioning

confidence: 99%

Prediction of convective heat transfer coefficients for the upper respiratory tracts of rat, dog, monkey, and humans

Mitsumune

Kuga

et al. 2016

In vivo studies involving mammal surrogate models for toxicology studies have restrictions related to animal protection and ethics. Computer models, i.e., in silico models, have great potential to contribute towards essential understanding of heat and mass transfer phenomena in respiratory tracts in place of in vivo and in vitro studies. Here, we developed numerical upper airway models of a rat, a dog, a monkey, and two humans by using computed tomography data and then applied computational fluid dynamics analysis. Convective heat transfer coefficients were precisely analysed as a function of breathing airflow rate. Based on the computational fluid dynamics simulation results, the correlations between Nusselt (Nu) number and the product of the Reynolds (Re) and Prandtl (Pr) numbers were summarized. The heat transfer efficiency (order of h c and correlation of Nu and RePr) in the upper airway of the dog seems to match those of the human models. On the other hand, the results for the rat and monkey showed clear differences compared with those of human models. The identified fundamental qualities of convective heat transfer phenomena in airways for rats, dogs, monkeys, and humans, have enabled discussions about quantitative differences of heat and mass transfer efficiency between different animals/species.