Computational Fluid Dynamics Investigation of Human Aspiration in Low-Velocity Air: Orientation Effects on Mouth-Breathing Simulations

Conductive olfactory dysfunction (COD) is caused by an obstruction in the nasal cavity and is characterized by changeable olfaction. COD can occur even when the olfactory cleft is anatomically normal, and therefore, the cause in these cases remains unclear. Herein, we used computational fluid dynamics to examine olfactory cleft airflow with a retrospective cohort study utilizing the cone beam computed tomography scan data of COD patients. By measuring nasal–nasopharynx pressure at maximum flow, we established a cut-off value at which nasal breathing can be differentiated from combined mouth breathing in COD patients. We found that increased nasal resistance led to mouth breathing and that the velocity and flow rate in the olfactory cleft at maximum flow were significantly reduced in COD patients with nasal breathing only compared to healthy olfactory subjects. In addition, we performed a detailed analysis of common morphological abnormalities associated with concha bullosa. Our study provides novel insights into the causes of COD, and therefore, it has important implications for surgical planning of COD, sleep apnea research, assessment of adenoid hyperplasia in children, and sports respiratory physiology.

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Simulation and optimization of airlift external circulation membrane bioreactor using computational fluid dynamics

Water Science & Technology ◽

10.2166/wst.2014.079 ◽

2014 ◽

Vol 69 (9) ◽

pp. 1846-1852 ◽

Cited By ~ 5

Author(s):

Zhang Qing ◽

Xu Rongle ◽

Zheng Xiang ◽

Fan Yaobo

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Membrane Fouling ◽

Membrane Bioreactor ◽

Membrane Surface ◽

Aeration Tank ◽

Low Velocity ◽

Simulation And Optimization ◽

External Circulation ◽

Membrane Modules

The airlift external circulation membrane bioreactor (AEC-MBR) is a new MBR consisting of a separated aeration tank and membrane tank with circulating pipes fixed between the two tanks. The circulating pipe is called a H circulating pipe (HCP) because of its shape. With the complex configuration, it was difficult but necessary to master the AEC-MBR's hydraulic characteristics. In this paper, simulation and optimization of the AEC-MBR was performed using computational fluid dynamics. The distance from diffusers to membrane modules, i.e. the height of gas–liquid mixing zone (hm), and its effect on velocity distribution at membrane surfaces were studied. Additionally, the role of HCP and the effect of HCP's diameter on circulation were simulated and analyzed. The results showed that non-uniformity of cross-flow velocity existed in the flat-plate membrane modules, and the problem could be alleviated by increasing hm to an optimum range (hm/B ≥ 0.55; B is total static depth). Also, the low velocity in the boundary layer on the membrane surface was another reason for membrane fouling. The results also suggested that HCP was necessary and it had an optimum diameter to make circulation effective in the AEC-MBR.

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Computational Fluid Dynamics Analysis of Compressible Flow Through a Converging-Diverging Nozzle using the k-ε Turbulence Model

Engineering, Technology & Applied Science Research ◽

10.48084/etasr.3140 ◽

2020 ◽

Vol 10 (1) ◽

pp. 5180-5185 ◽

Cited By ~ 1

Author(s):

M. W. Khalid ◽

M. Ahsan

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Combustion Chamber ◽

Turbulence Model ◽

High Velocity ◽

Chemical Potential ◽

Low Velocity ◽

Ansys Fluent ◽

Computational Fluid Dynamics Analysis ◽

Flow Through

The thrust produced by a rocket motor is mainly dependent upon the expansion of the product gases through a nozzle. The nozzle is used to accelerate the gases produced in the combustion chamber and convert the chemical-potential energy into kinetic energy so that the gases exit the nozzle at very high velocity. It converts the high pressure, high temperature, and low-velocity gas in the combustion chamber into high-velocity gas of lower pressure and low temperature. The design of a nozzle has particular importance in determining the thrust and performance of a rocket. In recent years, it has received considerable attention as it directly impacts the overall performance of the rocket. This paper aims to analyze the variation of flow parameters like pressure, Mach number, and velocity using Finite Volume Method (FVM) solver with the standard k-ε turbulence model in Computational Fluid Dynamics (CFD). The simulation of shockwave inside the divergent nozzle section through CFD is also investigated. In this regard, a nozzle has been designed using Design Modeler, and CFD analysis of flow through the nozzle has been carried out using ANSYS Fluent. The model results are compared with theoretically calculated results, and the difference is negligible.

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