scholarly journals Mathematical Model of Airflow and Solid Particles Transport in The Human Nasal Cavity

2021 ◽  
Vol 16 (2) ◽  
pp. 349-366
Author(s):  
P.V. Trusov ◽  
N.V. Zaitseva ◽  
M.Yu. Tsinker ◽  
A.V. Nekrasova
Keyword(s):  
Mathematical Model ◽  
Nasal Cavity ◽  
Particle Diameter ◽  
Suspended Particles ◽  
Machine Building ◽  
Solid Particles ◽  
Dust Particles ◽  
Multiphase Mixture ◽  
Different Temperatures ◽  
The Right

As part of the mathematical model of the human respiratory system, a submodel is considered for the study of the non-steady airflow with solid particles (suspended particulate matter (PM) / dust particles) and the deposition of particles of various sizes in the human nasal cavity. It is assumed that the nasal cavity is divided by the bone-cartilaginous septum into two symmetrical (relative to the nasal septum) parts; the average geometry of the right part of the human nasal cavity is considered. The inhaled air is considered as a multiphase mixture of homogeneous single-component gas and solid dust particles. The Eulerian-Lagrangian approach to modeling the motion of a multiphase mixture is used: a viscous liquid model is used to describe the motion of the carrier gas phase; the carried phase (dust particles) is modeled as separate inclusions of various sizes. The process of heating the inhaled air due to its contact with the walls is also taken into account. The features of the unsteady flow of a multiphase air mixture with dust particles were obtained using Ansys CFX for several scenarios. It has been noted that when studying the airflow in the nasal cavity, it is necessary to take into account the presence of turbulence, for which it is proposed to use the k-ω model. The velocity fields of inhaled air in the nasal cavity have been obtained; presented temperature distributions in the nasal cavity at different time points; made estimates of air heating at different temperatures of inhaled air; gave estimates of the proportion of deposited particles in the nasal cavity depending on the particle size for real machine-building production; presented trajectories of movement of suspended particles. Thus, it is shown that more than 99.7 % of particles with a diameter of more than 10 microns deposit in the human nasal cavity; as the particle diameter and mass decrease, the proportion of deposited particles decreases. Suspended particles with a size of less than 2.5 microns almost do not deposit in the nasal cavity. They can penetrate deeper into the lower airways and lungs of a person with the inhaled air and, having fibrogenic and toxic effect, can cause diseases. The results obtained are in good agreement with the results of individual studies performed by other scientists. Further development of the model involves studying airflow in the human lungs and modeling the formation of diseases caused by the harmful effects of environmental factors (including dust particles) entering the human body by inhalation.

scholarly journals Validation of friction factor predictions in vertical slurry flows with coarse particles

2020 ◽  
Vol 68 (2) ◽  
pp. 119-127 ◽  
Author(s):  
Artur Bartosik
Keyword(s):  
Mathematical Model ◽  
Reynolds Number ◽  
Friction Factor ◽  
Particle Diameter ◽  
Solid Particles ◽  
Coarse Particles ◽  
Carrier Liquid ◽  
Different Types ◽  
Slurry Flows ◽  
The Mathematical Model

AbstractThe paper presents validation of a mathematical model describing the friction factor by comparing the predicted and measured results in a broad range of solid concentrations and mean particle diameters. Three different types of solids, surrounded by water as a carrier liquid, namely Canasphere, PVC, and Sand were used with solids density from 1045 to 2650 kg/m3, and in the range of solid concentrations by volume from 0.10 to 0.45. All solid particles were narrowly sized with mean particle diameters between 1.5 and 3.4 mm. It is presented that the model predicts the friction factor fairly well. The paper demonstrates that solid particle diameter plays a crucial role for the friction factor in a vertical slurry flow with coarse solid particles. The mathematical model is discussed in reference to damping of turbulence in such flows. As the friction factor is below the friction for water it is concluded that it is possible that the effect of damping of turbulence is included in the KB function, which depends on the Reynolds number.

Drug delivery in the nasal cavity after functional endoscopic sinus surgery: a computational fluid dynamics study

2012 ◽  
Vol 126 (5) ◽  
pp. 487-494 ◽  
Author(s):  
X B Chen ◽  
H P Lee ◽  
V F H Chong ◽  
D Y Wang
Keyword(s):  
Nasal Cavity ◽  
Maxillary Sinus ◽  
Endoscopic Sinus Surgery ◽  
Particle Deposition ◽  
Particle Diameter ◽  
Functional Endoscopic Sinus Surgery ◽  
Sinus Surgery ◽  
Airflow Rate ◽  
Sinus Cavity ◽  
The Right

AbstractBackground:Intranasal medication is commonly used for nasal disease. However, there are no clear specifications for intranasal medication delivery after functional endoscopic sinus surgery.Methods:A three-dimensional model of the nasal cavity was constructed from computed tomography scans of an adult Chinese male who had previously undergone functional endoscopic sinus surgery in the right nasal cavity. Computational fluid dynamic simulations modelled airflow and particle deposition, based on discrete phase models.Results:In the right nasal cavity, more particles passed through the upper dorsal region, around the surgical area, and streamed into the right maxillary sinus region. In the left cavity, particles were distributed more regularly and uniformly in the ventral region around the inferior turbinate. A lower inspiratory airflow rate and smaller initial particle velocity assisted particle deposition within the right maxillary sinus cavity. In the right nasal cavity, the optimal particle diameter was approximately 10−5 m for maxillary sinus cavity deposition and 3 × 10−6 m for bottom region deposition. In the right nasal cavity, altered back head tilt angles enhanced particle deposition in the top region of the surgical area, and altered right side head tilt angles helped enhance maxillary sinus cavity deposition.Conclusion:This model indicates that a moderate inspiratory airflow rate and a particle diameter of approximately 10−5 m should improve intranasal medication deposition into the maxillary sinus cavity following functional endoscopic sinus surgery.

Investigation of the different particle size dust releases from rigid filter candles during pulse-jet cleaning

2021 ◽  
pp. 095440622110179
Author(s):  
Xin Luan ◽  
Zhongli Ji ◽  
Longfei Liu ◽  
Ruifeng Wang
Keyword(s):  
Particle Size ◽  
Critical Role ◽  
Operating Conditions ◽  
Solid Particles ◽  
Dust Particles ◽  
Cleaning Efficiency ◽  
Term Operation ◽  
Cleaning Performance ◽  
Experimental Apparatus ◽  
Pulse Jet

Rigid filters made of ceramic or metal are widely used to remove solid particles from hot gases at temperature above 260 °C in the petrochemical and coal industries. Pulse-jet cleaning of fine dust from rigid filter candles plays a critical role in the long-term operation of these filters. In this study, an experimental apparatus was fabricated to investigate the behavior of a 2050 mm filter candle, which included monitoring the variation of pressure dynamic characteristics over time and observing the release of dust layers that allowed an analysis of the cleaning performance of ISO 12103-1 test dusts with different particle size distributions. These results showed the release behavior of these dusts could be divided into five stages: radial expansion, axial crack, flaky release, irregular disruption and secondary deposition. The cleaning performance of smaller sized dust particles was less efficient as compared with larger sized dust particles under the same operating conditions primarily because large, flaky-shaped dust aggregates formed during the first three stages were easily broken into smaller, dispersed fragments during irregular disruption that forced more particles back to the filter surface during secondary deposition. Also, a “low-pressure and long-pulse width” cleaning method improved the cleaning efficiency of the A1 ultrafine test dust from 81.4% to 95.9%.

Theoretical Analysis of CFD-DEM Mathematical Model Solution Change With Varying Computational Cell Size

2018 ◽  
Author(s):  
Annette Volk ◽  
Urmila Ghia
Keyword(s):  
Mathematical Model ◽  
Standard Deviation ◽  
Cell Size ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Independent Solution ◽  
Model Verification ◽  
Computational Cell ◽  
Drag Laws ◽  
Fraction Method

Successful verification and validation is crucial to build confidence in the application of coupled Computational Fluid Dynamics - Discrete Element Method (CFD-DEM). Model verification includes ensuring a mesh-independent solution, which poses a major difficulty in CFD-DEM due to the complicated solution relationship with computational cell size. In this paper, we investigate the theoretical relationship between the solution and computational cell size by tracing the effects of a change in cell size through the mathematical model. The porosity profile for simulations of fixed-particle beds is determined to be Gaussian, and the average and standard deviation of the representative distribution are reported against cell size. We find the standard deviation of bed porosity increases exponentially as the cell size is reduced, and the drag calculations are very sensitive to changes in the porosity standard deviation, resulting in an exponential change in expected drag when the cell size is small relative to the particle diameter. The divided volume fraction method of porosity calculation is shown to be superior to the centred volume fraction method, as it reduces the porosity standard deviation. The sensitivity of five popular drag laws to changes in the porosity profile is presented, and the Ergun and Beetstra drag laws are shown to be the least sensitive to changes in the cell size.

scholarly journals Two-Phase Dusty Fluid Flow Along a Rotating Axisymmetric Round-Nosed Body

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Sadia Siddiqa ◽  
Naheed Begum ◽  
M. A. Hossain ◽  
Rama Subba Reddy Gorla
Keyword(s):  
Boundary Layer ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Solid Particles ◽  
Dust Particles ◽  
Computational Domain ◽  
Two Phase ◽  
Carrier Fluid ◽  
Boundary Layer Equations ◽  
Implicit Finite Difference

This article is concerned with the class of solutions of gas boundary layer containing uniform, spherical solid particles over the surface of rotating axisymmetric round-nosed body. By using the method of transformed coordinates, the boundary layer equations for two-phase flow are mapped into a regular and stationary computational domain and then solved numerically by using implicit finite difference method. In this study, a rotating hemisphere is used as a particular example to elucidate the heat transfer mechanism near the surface of round-nosed bodies. We will investigate whether the presence of dust particles in carrier fluid disturbs the flow characteristics associated with rotating hemisphere or not. A comprehensive parametric analysis is presented to show the influence of the particle loading, the buoyancy ratio parameter, and the surface of rotating hemisphere on the numerical findings. In the absence of dust particles, the results are graphically compared with existing data in the open literature, and an excellent agreement has been found. It is noted that the concentration of dust particles’ parameter, Dρ, strongly influences the heat transport rate near the leading edge.

scholarly journals The β-cyclodextrin/benzene complex and its hydrogen bonds – a theoretical study using molecular dynamics, quantum mechanics and COSMO-RS

2013 ◽  
Vol 9 ◽  
pp. 118-134 ◽  
Author(s):  
Jutta Erika Helga Köhler ◽  
Nicole Grczelschak-Mick
Keyword(s):  
Molecular Dynamics ◽  
Quantum Mechanics ◽  
Hydrogen Bonds ◽  
Md Simulations ◽  
Benzene Molecule ◽  
Glucose Unit ◽  
Hand Orientation ◽  
Different Temperatures ◽  
Dynamics Simulations ◽  
The Right

Four highly ordered hydrogen-bonded models of β-cyclodextrin (β-CD) and its inclusion complex with benzene were investigated by three different theoretical methods: classical quantum mechanics (QM) on AM1 and on the BP/TZVP-DISP3 level of approximation, and thirdly by classical molecular dynamics simulations (MD) at different temperatures (120 K and 273 to 300 K). The hydrogen bonds at the larger O2/O3 rim of empty β-CDs prefer the right-hand orientation, e.g., O3-H…O2-H in the same glucose unit and bifurcated towards …O4 and O3 of the next glucose unit on the right side. On AM1 level the complex energy was −2.75 kcal mol−1 when the benzene molecule was located parallel inside the β-CD cavity and −2.46 kcal mol−1 when it was positioned vertically. The AM1 HOMO/LUMO gap of the empty β-CD with about 12 eV is lowered to about 10 eV in the complex, in agreement with data from the literature. AM1 IR spectra displayed a splitting of the O–H frequencies of cyclodextrin upon complex formation. At the BP/TZVP-DISP3 level the parallel and vertical positions from the starting structures converged to a structure where benzene assumes a more oblique position (−20.16 kcal mol−1 and −20.22 kcal mol−1, resp.) as was reported in the literature. The character of the COSMO-RS σ-surface of β-CD was much more hydrophobic on its O6 rim than on its O2/O3 side when all hydrogen bonds were arranged in a concerted mode. This static QM picture of the β-CD/benzene complex at 0 K was extended by MD simulations. At 120 K benzene was mobile but always stayed inside the cavity of β-CD. The trajectories at 273, 280, 290 and 300 K certainly no longer displayed the highly ordered hydrogen bonds of β-CD and benzene occupied many different positions inside the cavity, before it left the β-CD finally at its O2/O3 side.

scholarly journals Tourist enterprise marketing complex: international and national aspect

2021 ◽  
pp. 124-127
Author(s):  
О.В. Птащенко ◽  
В.А. Вовк
Keyword(s):  
Development Strategy ◽  
Modern Technology ◽  
Machine Building ◽  
Enterprise Management ◽  
Goods And Services ◽  
Marketing Activities ◽  
Marketing Variables ◽  
Business Entities ◽  
The Right

The main features of the marketing complex for the enterprises of the tourist branch are considered in the article. In a market economy, the concept of marketing, as part of improving enterprise management, becomes an integral part of its activities. With the help of a number of controlled marketing variables, business entities can influence customers, stimulate them, encouraging them to certain, desirable for the company actions in the market until the purchase. One of the elements of the marketing complex is the brand. Increasingly, it is important to use it as one of the most important marketing factors that can ensure the success of the company in the market. To a large extent, this success is due to choosing the right branding strategy. This choice, as well as the positioning and development strategy of the brand directly depend on the chosen variety. In addition, it should be noted that the purpose of marketing is not only to benefit companies, but also to build long-term relationships with consumers, meet their demands, improve the quality of goods and services, improve the conditions of their acquisition. It should also be noted that the formation of marketing activities at the enterprise today is impossible without a focus on modern technology. Such technologies include Internet marketing as a modern way of building a business. Principles of tourism marketing: constant search and maximum respect for the consumer, focus on his needs and requirements, which provide the market is not goods and services, and ways to solve consumer problems; flexibility in achieving the set goal by adapting to the requirements of the market with a simultaneous targeted impact on it; a comprehensive approach to the development of marketing plans, which involves the use not of individual marketing activities, and a set of marketing, a combination of individual elements which allows you to achieve a certain goal; focus on the long-term prospects of the enterprise. Thus, the main purpose of each enterprise is to achieve profitability and stability of services. Today it is possible to achieve only through the introduction of basic principles of marketing and the formation of a comprehensive mechanism of marketing activities. At the same time, the high cost of enterprises, for example, machine-building industry, agricultural machinery enterprises should be compensated by the introduction of modern advanced production technologies, rational use of fundamentally new materials, introduction of modern technological policy, including marketing and work aimed at improving skills. All this once again confirms the importance of marketing management today and as a consequence of the constant introduction of the latest marketing tools.

scholarly journals Interpolation of Boundary Condition at Time-Interval of Unknown Lenghth for the Problem of Convective Diffusion in a Three-Layered Water Filter

2019 ◽  
pp. 25-28
Author(s):  
Olha Chernukha ◽  
Yurii Bilushchak
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Boundary Condition ◽  
Boundary Value Problem ◽  
Convective Diffusion ◽  
Lower Boundary ◽  
Time Interval ◽  
Water Filter ◽  
The Right

On the basis of mathematical model of convectivediffusion in a three-layered filter it is formulated a contactinitial-boundary value problem for description of mass transferof pollution accompanying the sorption processes. It is proposedthe algorithm for establishing the estimation of values of soughtfunction (concentration of pollution) at the lower boundary of thefilter on the basis of the interpolation of experimental data. It istaken into account that the right end of the interpolation segmentis unknown. It is determined the exact solutions of contact-initialboundaryvalue problems of mass transfer with provision forboth diffusive and convective mechanisms of transfer as well assorption processes, which is based on integral transformationsover space variables in the contacting regions. Is it designedsoftware and established regularities of convective diffusionprocess in the three-layered filter.

scholarly journals Primary mucosal malignant melanoma of the nasal cavity

2020 ◽  
Vol 6 (5) ◽  
pp. 988
Author(s):  
Subrata Mukhopadhyay ◽  
Misbahul Haque
Keyword(s):  
Computed Tomography ◽  
Malignant Melanoma ◽  
Nasal Cavity ◽  
Maxillary Antrum ◽  
Positron Emission ◽  
Recurrent Epistaxis ◽  
Mucosal Malignant Melanoma ◽  
The Right ◽  
Primary Mucosal Malignant Melanoma ◽  
Enhanced Computed Tomography

<p>Primary mucosal melanoma of the nasal cavity and paranasal sinuses is a very aggressive and rare disease with only about 0.5 % of malignant melanoma arising from the nasal cavity. There are only few reports from India. We report a rare case of sino-nasal mucosal malignant melanoma in a 58 years old female who presented with blackish coloured sino-nasal mass involving right nasal cavity, spontaneous and recurrent epistaxis and obliteration of the right naso-labial fold with occasional pain in the past 10 months. Contrast enhanced computed tomography scan showed a heterogenous mass involving right nasal cavity, right maxillary antrum and right ethmoidal area. A positron emission tomography computed tomography was also done which showed increased uptake in the region mentioned above. Initial biopsy, the mass was diagnosed as malignant melanoma. Total maxillectomy was performed with plan of post-operative radiotherapy.</p>

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