A study on the three-dimensional unsteady state of indoor radon diffusion under different ventilation conditions

2020 ◽  
pp. 102599
Author(s):  
Dong Xie ◽  
Yangxi Wu ◽  
Chenhua Wang ◽  
Chuck Wah Yu ◽  
Ling Tian ◽  
...  
Keyword(s):  
Indoor Radon ◽  
Three Dimensional ◽  
Unsteady State ◽  
Radon Diffusion ◽  
Ventilation Conditions

scholarly journals Radon measurements with CR-39 track detectors at specific locations in Turkey

2004 ◽  
Vol 19 (1) ◽  
pp. 46-49 ◽  
Author(s):  
Asiye Ulug ◽  
Melek Karabulut ◽  
Nilgün Celebi
Keyword(s):  
Radon Concentration ◽  
Indoor Radon ◽  
Active Faults ◽  
Indoor Radon Concentration ◽  
Arithmetic Means ◽  
Radon Measurements ◽  
New Buildings ◽  
Main Factor ◽  
Ventilation Conditions ◽  
Radon Concentrations

Indoor radon concentration levels at three sites in Turkey were measured using CR-39 solid state nuclear track detectors. The annual mean of radon concentration was estimated on the basis of four quarter measurements at specific locations in Turkey. The measuring sites are on the active faults. The results of radon measurements are based on 280 measurements in doors. The annual arithmetic means of radon concentrations at three sites (Isparta Egirdir, and Yalvac) were found to be 164 Bqm?3, 124 Bqm?3, and 112 Bqm?3 respectively, ranging from 78 Bqm?3 to 279 Bqm?3. The in door radon concentrations were investigated with respect to the ventilation conditions and the age of buildings. The ventilation conditions were determined to be the main factor affecting the in door radon concentrations. The in door radon concentrations in the new buildings were higher than ones found in the old buildings.

Three-Dimensional Numerical Simulation of the Fluid Dynamics in a Coronary Stent

2009 ◽  
Author(s):  
F. Gori ◽  
A. Boghi ◽  
M. Amitrano
Keyword(s):  
Fluid Dynamic ◽  
Three Dimensional ◽  
Coronary Stent ◽  
Shear Stresses ◽  
Unsteady State ◽  
Hemodynamic Variables ◽  
Stent Geometry ◽  
Severe Coronary Artery ◽  
Wall Shear ◽  
Artery Disease

Stents are commonly used to restore blood flow in patients with severe coronary artery disease. Local hemodynamic variables, as wall shear stress, have an important role in the restenosis and their distribution depends on the stent geometry. The objective of the present study is to carry out CFD simulations in a realistic 3D geometry of a coronary stent in physiological conditions. A comparison is performed between two reconstructed stents, made of 12 rings and similar to the real coronary ones, which differ by the position of the struts, where the first type is with closed cells and the second one with open cells. The artery is modeled as a cylinder with rigid walls and the blood is assumed as incompressible Newtonian fluid in laminar flow with constant physical properties. The commercial computational fluid dynamic code FLUENT is used with a mesh composed of non uniform tetrahedrons. The simulations are performed in steady and unsteady state. Wall shear stresses, WSS, as well as its time variations, are investigated in unsteady state with the conclusion that the stent with closed cells have a better fluid dynamic behavior.

Three-Dimensional Numerical Simulation of Non-Newtonian Blood in Two Coronary Stents

2010 ◽  
Author(s):  
F. Gori ◽  
A. Boghi
Keyword(s):  
Fluid Dynamic ◽  
Three Dimensional ◽  
Casson Fluid ◽  
Coronary Stents ◽  
Unsteady State ◽  
Cfd Simulations ◽  
3D Geometry ◽  
Time Variations ◽  
Rigid Walls ◽  
Newtonian Behavior

The objective of the present study is to carry out CFD simulations in a realistic 3D geometry of two coronary stents in physiological conditions and to assess the influence of the non-Newtonian behavior of blood, modeled as Casson fluid. The stents used are made of 12 rings and are similar to real coronary ones. Artery is modeled as a cylinder with rigid walls and the blood is assumed as incompressible non-Newtonian fluid in laminar flow. A commercial computational fluid dynamic code is used with a mesh composed of non uniform tetrahedrons. The simulations are performed in steady and unsteady state. Wall Shear Stress, as well as its time variations and the non-Newtonian behavior, are investigated in unsteady state. Results suggest that the Newtonian behavior is leading to an overestimation of the restenosis percent.

scholarly journals Three dimensional coupled reaction–diffusion modeling of calcium and inositol 1,4,5-trisphosphate dynamics in cardiomyocytes

RSC Advances ◽  
2019 ◽  
Vol 9 (72) ◽  
pp. 42459-42469 ◽  
Author(s):  
Nisha Singh ◽  
Neeru Adlakha
Keyword(s):  
Mathematical Model ◽  
Three Dimensional ◽  
Reaction Diffusion ◽  
Unsteady State ◽  
Diffusion Modeling ◽  
Inositol 1,4,5 Trisphosphate ◽  
Coupled Reaction

We propose a three-dimensional unsteady-state mathematical model to describe the mechanism of cardiomyocytes.

Aerodynamic Comfort Analysis of High-Speed Trains Passing each other at the same Speed through a Tunnel

2011 ◽  
Vol 90-93 ◽  
pp. 2147-2151
Author(s):  
Ya Guang Yan ◽  
Qing Shan Yang ◽  
Jian Zhang
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Pressure Change ◽  
Unsteady State ◽  
Transient Pressure ◽  
Tunnel Length ◽  
Simulation Calculation ◽  
Aerodynamic Effect ◽  
High Speed Trains ◽  
Volume Method

On the basis of the three-dimensional,compressible,unsteady-state,viscous N-S Equation and k-ε turbulence model,the simulation calculation is made with the finite volume method on the aerodynamic effect of two high-speed trains passing each other at the same speed through a tunnel,simulating the pressure change,analysising regularity of the pressure,researching comfort in the train.The following conclusions have been drawn from research:The maximum of transient pressure is concerned with the meeting point,when the two high-speed trains meet in tunnel.When the length,the speed and the sealing factor of the train are same,the transient pressure is maximum with the trains meeting at the midpoint of tunnel.When the tunnel length,the speed of the train,the sealing factor and the point of meeting are same,the transient pressure of the longer train is maximum.When the sealing factor is greater than 15s,the standard of permissible pressure (1250Pa\3s) can be satisfied with all circumstances.

Study of the Phan-Thien–Tanner Equation of Viscoelastic Blood Non- Newtonian Flow in a Pipe-Shaped Artery under an Emotion-Induced Pressure Gradient

2012 ◽  
Vol 67 (10-11) ◽  
pp. 628-632
Author(s):  
Karem Boubaker ◽  
Yasir Khan
Keyword(s):  
Fluid Flow ◽  
Pressure Gradient ◽  
Three Dimensional ◽  
Unsteady State ◽  
Newtonian Flow ◽  
Shooting Technique ◽  
Radial Profiles ◽  
Boubaker Polynomials ◽  
Newtonian Method ◽  
Expansion Scheme

In this paper, a three-dimensional, unsteady state non-Newtonian fluid flow in a pipe-shaped artery of viscoelastic blood is considered in the presence of emotion-induced pressure gradient. The results have been expressed in terms of radial profiles of both axial velocity and viscosity and were presented numerically by using the shooting technique coupled with the Newtonian method and the Boubaker polynomials expansion scheme. The effects of some parameters on the dynamics are analyzed.

Study of Indoor Radon/ Thoron Concentration with Respect to Construction Types of Dwellings in Mizoram, India

2018 ◽  
Vol 6 (2) ◽  
pp. 44-46
Author(s):  
L.Z. Chhangte ◽  
◽  
P.C. Rohmingliana ◽  
Zirlian ngura ◽  
B.K. Sahoo ◽  
...  
Keyword(s):  
Indoor Radon ◽  
Nationwide Survey ◽  
Survey Result ◽  
Cement Concrete ◽  
Indoor Concentration ◽  
Building Type ◽  
Single Entry ◽  
Crawl Space ◽  
Ventilation Conditions

Indoor radon and thoron concentrations have been measured in the year 2015-2016 using the newly developed pin-hole based radon/thoron discriminating dosimeters with single entry. The measurements have been carried out in fifty dwellings of eight different villages/town situated in Saiha and Lawngtlai District, Mizoram. Dwellings were selected from the building type along with an idea of different ventilation conditions which affects the indoor concentration. Reinforce Cement Concrete (RCC) type of buildings are found to have the highest concentration of indoor radon (100.34 ± 7 Bq/m3) and thoron (41.41 ± 18 Bq/m3) and grounded house are found to have higher concentration compared to that of house with crawl space. However, the concentrations obtained in this work lies in the range covered by nationwide survey result as well as the ICRP regulations.

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