scholarly journals Computational Fluid Dynamics Simulation of Airflow and Air Pattern in the Living Room for Reducing Coronavirus Exposure

2021 ◽  
Author(s):  
Majid Bayatian ◽  
Khosro Ashrafi ◽  
Zahra Amiri ◽  
Elahe Jafari
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Indoor Air ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Dynamics Simulation ◽  
Living Room ◽  
Air Velocity ◽  
Cfd Validation ◽  
Airflow Pattern

Abstract Viruses can be transmitted in indoor environments. Important factors in Indoor Air Quality (IAQ) are air velocity, relative humidity, temperature, and airflow pattern and Computational fluid dynamics (CFD) can use for IAQ assessment. The objective of this study is to CFD simulation in the living room to the prediction of the air pattern and air velocity. A computational fluid dynamic model was applied for airflow pattern and air velocity simulation. For simulation, GAMBIT, FLUENT, and CFD post software were used as preprocessing, processing, and post-processing, respectively. CFD validation was carried out by comparing the computed data with the experimental measurements. The final mesh number was set to 1,416,884 elementary cells and SIMPLEC algorithm was used for pressure-velocity coupling. PERSTO, and QUIK schemes have been used for the pressure terms, and the other variables, respectively. Simulations were carried out in ACH equals 3, 6 and 8 in four lateral walls. The maximum error and root mean square error from the air velocity were 14% and 0.10, respectively. Terminal settling velocity and relaxation time were equal to 0.302 ×10− 2 m/s and 0.0308 ×10− 2 s for 10 µm diameter particles, respectively. The stopping distance was 0.0089m and 0.011m for breathing and talking, respectively. The maximum of mean air velocity is in scenario 4 with ACH = 8 that mean air velocity is equal to 0.31 in 1.1m height, respectively. The results of this study showed that avoiding family gatherings is necessary for exposure control and suitable airflow and pattern can be improving indoor air conditions.

Validation of the free area method for modelling fabric air dispersion system without orifices in computational fluid dynamics simulation

2017 ◽  
Vol 27 (7) ◽  
pp. 969-982 ◽  
Author(s):  
Fu-Jiang Chen ◽  
Qin-Yu Wu ◽  
Dan-Dan Huang ◽  
Yun Zhang ◽  
Wang Lu ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Ventilation System ◽  
Dynamics Simulation ◽  
Complex Flow ◽  
Air Velocity ◽  
Dispersion System ◽  
Air Dispersion ◽  
Free Area

The fabric air dispersion system (FADS) is a ventilation terminal made of special polymer fabric. The porous structure of the fabric causes complex flow motion. Due to its advantages over the conventional ventilation system, i.e. ducts and diffusers, the FADS has been widely favoured by architects and researchers. In computational fluid dynamics (CFD) simulation the FADS is usually simplified into a free opening with an area equal to all pores and perforations, called the free area (FA) method in this present work. However, the effectiveness of this simplified method has not been validated. The present work took a half cylindrical FADS without orifices as an example and employed the FA method to simulate the airflow properties inside a chamber under isothermal and non-isothermal conditions. The simulated distributions of air velocity and temperature were compared with those by the direct description (DD) method. Meanwhile, the uniformity of air velocity distribution close to the FADS was validated against test data and the flow visualization using the dry ice as a smoking material. Results demonstrate that the FA method is effective and easy to implement, and performs as well as the DD method in predicting the distribution of airflow generated by the FADS without orifices.

A Study on the Performance of Stratified Air Conditioning Design in Assembly Halls – A Case Study at the Dazhi Cultural Center in Taiwan

2013 ◽  
Vol 368-370 ◽  
pp. 599-602 ◽  
Author(s):  
Ian Hung ◽  
Hsien Te Lin ◽  
Yu Chung Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Indoor Air ◽  
Air Conditioning ◽  
Cfd Simulation ◽  
Indoor Temperature ◽  
Cultural Center ◽  
Computational Fluid Dynamics Cfd

This study focuses on the performance of air conditioning design at the Dazhi Cultural Center and uses a computational fluid dynamics (CFD) simulation to discuss the differences in wind velocity and ambient indoor temperature between all-zone air conditioning design and stratified air conditioning design. The results have strong implications for air conditioning design and can improve the indoor air quality of assembly halls.

Particle Image Velocimetry Experiment and Computational Fluid Dynamics Simulation of Flow Around Rigid Cylinder

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Guangyao Wang ◽  
Ye Tian ◽  
Spyros A. Kinnas
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Particle Image Velocimetry ◽  
Vector Fields ◽  
Particle Image ◽  
Cfd Simulation ◽  
Dynamics Simulation ◽  
Reynolds Stresses ◽  
Rigid Cylinder ◽  
Image Velocimetry

This work focuses on the study of the flow around a rigid cylinder with both particle image velocimetry (PIV) experiment and computational fluid dynamics (CFD) simulation. PIV measurements of the flow field downstream of the cylinder are first presented. The boundary conditions for CFD simulations are measured in the PIV experiment. Then the PIV flow is compared with both Reynolds-averaged Navier–Stokes (RANS) two-dimensional (2D) and large eddy simulation (LES) three-dimensional (3D) simulations performed with ANSYS fluent. The velocity vector fields and time histories of velocity are analyzed. In addition, the time-averaged velocity profiles and Reynolds stresses are analyzed. It is found that, in general, LES (3D) gives a better prediction of flow characteristics than RANS (2D).

scholarly journals A Hybrid RANS-LES Computational Fluid Dynamics Simulation of an FDA Medical device benchmark

Mechanika ◽  
2019 ◽  
Vol 25 (4) ◽  
pp. 291-298
Author(s):  
Primož Drešar ◽  
Jožef Duhovnik
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulence Models ◽  
The United States ◽  
Dynamics Simulation ◽  
Sudden Expansion ◽  
Detached Eddy Simulation ◽  
Cfd Validation ◽  
Eddy Simulation ◽  
Advection Schemes

Computational fluid dynamics (CFD) is a valuable tool that complements experimental data in the development of medical devices. The reliability of CFD still presents an issue and for that reason, no standardized approaches are currently available. The United States Food and Drug Administration (FDA) has initiated the development of a program for CFD validation, and has presented an idealized nozzle benchmark model. In this study, a nozzle flow with sudden expansion has been simulated using advanced RANS-LES turbulence models. Such models partially resolve the flow and are cheaper in computer resources and time in comparison to the Large Eddy Simulation (LES). Furthermore, they are more accurate than standard Reynolds-averaged Navier-Stokes (RANS) models. A collection of hybrid turbulence models has been investigated: Detached Eddy Simulation (DES), Stress Blended Eddy Simulation (SBES), and Scale Adaptive Simulation (SAS), and compared to a standard RANS Shear Stress Transport (SST) model. Subsequently, all models were validated by experimental results already published by different research groups. Particle Image Velociometry (PIV) experiments were performed by inter-laboratory study, and the results are available online for numerical validation.  The flow conditions in this study are only restricted to a turbulence flow at a Reynolds number of Re =6500. Complementing the turbulence models investigation, two advection schemes were tested: high resolution (HR) and bounded central difference scheme (BCD). Among all advanced models the SBES model with BCD scheme has the best agreement with the experimental values.

Computational Fluid Dynamics Simulation of the Right Coronary Artery Moving With the Cardiac Wall

2002 ◽  
Author(s):  
H. Hayashi ◽  
T. Yamaguchi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Coronary Artery ◽  
Right Coronary Artery ◽  
Cfd Simulation ◽  
Dynamics Simulation ◽  
Cardiac Wall ◽  
Computational Fluid Dynamics Cfd ◽  
The Right ◽  
Heart Wall

The beating motion of the heart wall, to which the major coronary arteries are fixed, is interesting, due to its possible mechanical influence on the flow inside the artery, and hence its effect on atherogenesis [1–2]. In this study, we conducted a computational fluid dynamics (CFD) simulation using a simplified model of the right coronary artery, which deforms with heart contractions. The results are discussed with respect to the local hemodynamics characteristics, particularly the streamline pattern and the wall shear stress distribution.

Application of Computational Fluid Dynamics Simulation to Squeeze Film Damper Analysis

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Gil Jun Lee ◽  
Jay Kim ◽  
Tod Steen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Cfd Simulation ◽  
Design Guidelines ◽  
Dynamics Simulation ◽  
Squeeze Film ◽  
Computational Time ◽  
Small Clearance ◽  
Computational Fluid Dynamics Cfd

Squeeze film dampers (SFDs) are used in high-speed turbomachinery to provide external damping to the system. Computational fluid dynamics (CFD) simulation is a highly effective tool to predict the performance of SFDs and obtain design guidance. It is shown that a moving reference frame (MRF) can be adopted for CFD simulation, which saves computational time significantly. MRF-based CFD analysis is validated, then utilized to design oil plenums of SFDs. Effects of the piston ring clearances, the oil groove, and oil supply ports are studied based on CFD and theoretical solutions. It is shown that oil plenum geometries can significantly affect the performance of the SFD especially when the SFD has a small clearance. The equivalent clearance is proposed as a new concept that enables quick estimation of the effect of oil plenum geometries on the SFD performance. Some design practices that have been adopted in industry are revisited to check their validity. Based on simulation results, a set of general design guidelines is proposed.

CFD Simulation and Computation of Pressure Loss of Resistance Muffler

2013 ◽  
Vol 694-697 ◽  
pp. 307-311
Author(s):  
Jia Wei Ren ◽  
Qin Yu Jiang ◽  
Zhen Wang
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Pressure Loss ◽  
Cfd Simulation ◽  
Internal Flow ◽  
Simulation Algorithm ◽  
Air Velocity ◽  
Loss Of Resistance ◽  
Computational Fluid Dynamics Cfd

Computational fluid dynamics (CFD) software was used to simulate the internal flow field of an example muffler, and compared the results with the experimental data, verifying the reliability of the simulation algorithm. On this basis, changed the example muffler structure, researched the pressure loss of muffler which was influenced by the insert duct, the position of the baffle and the inlet air velocity. The corresponding regularities have been obtained with the results of computations, which provide a basis for the design of the muffler.

scholarly journals Computational fluid dynamics simulation of wind-driven inter-unit dispersion around multi-storey buildings: Upstream building effect

2017 ◽  
Vol 28 (2) ◽  
pp. 217-234 ◽  
Author(s):  
Y. W. Dai ◽  
C. M. Mak ◽  
Z. T. Ai
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Concentration Field ◽  
Mass Conservation ◽  
Dynamics Simulation ◽  
Navier Stokes ◽  
Wind Effect ◽  
Tracer Gas ◽  
Airflow Pattern ◽  
Cfd Method

Previous studies on inter-unit dispersion around multi-storey buildings focused mostly on an isolated building. Considering that the presence of an upstream building(s) would significantly modify the airflow pattern around a downstream building, this study intends to investigate the influence of such changed airflow patterns on inter-unit dispersion characteristics around a multi-storey building due to wind effect. Computational fluid dynamics (CFD) method in the framework of Reynolds-averaged Navier-stokes modelling was employed to predict the coupled outdoor and indoor airflow field, and the tracer gas technique was used to simulate the dispersion of infectious agents between units. Based on the predicted concentration field, a mass conservation based parameter, namely re-entry ratio, was used to evaluate quantitatively the inter-unit dispersion possibilities and thus assess risks along different routes. The presence of upstream building(s) could disrupt the strong impingement of approaching flows but brings a more complex and irregular airflow pattern around the downstream multi-storey buildings, leading to a more scattered distribution of re-entry ratio values among different units and uncertain dispersion routes. Generally, the tracer gas concentration in most units was lower than those in an isolated building, although very high concentrations were found in some specific areas.

scholarly journals Hemodynamic analysis for stenosis microfluidic model of thrombosis with refined computational fluid dynamics simulation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yunduo Charles Zhao ◽  
Parham Vatankhah ◽  
Tiffany Goh ◽  
Rhys Michelis ◽  
Kiarash Kyanian ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Shear Rate ◽  
Cfd Simulation ◽  
Critical Role ◽  
Three Dimensions ◽  
Dynamics Simulation ◽  
Water Medium ◽  
Cfd Method

AbstractDisturbed blood flow has been increasingly recognized for its critical role in platelet aggregation and thrombosis. Microfluidics with hump shaped contractions have been developed to mimic microvascular stenosis and recapitulate the prothrombotic effect of flow disturbance. However the physical determinants of microfluidic hemodynamics are not completely defined. Here, we report a refined computational fluid dynamics (CFD) simulation approach to map the shear rate (γ) and wall shear stress (τ) distribution in the stenotic region at high accuracy. Using ultra-fine meshing with sensitivity verification, our CFD results show that the stenosis level (S) is dominant over the bulk shear rate (γ0) and contraction angle (α) in determining γ and τ distribution at stenosis. In contrast, α plays a significant role in governing the shear rate gradient (γ′) distribution while it exhibits subtle effects on the peak γ. To investigate the viscosity effect, we employ a Generalized Power-Law model to simulate blood flow as a non-Newtonian fluid, showing negligible difference in the γ distribution when compared with Newtonian simulation with water medium. Together, our refined CFD method represents a comprehensive approach to examine microfluidic hemodynamics in three dimensions and guide microfabrication designs. Combining this with hematological experiments promises to advance understandings of the rheological effect in thrombosis and platelet mechanobiology.

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