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Predominance of inhalation route in short-range transmission of respiratory viruses:Investigation based on Computational fluid dynamics

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Building Simulation 2023年第5期16卷 765-780页

作者： Wenzhao Chen Li Liu Jian Hang Yuguo Li Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina Department of Building Science Tsinghua UniversityBeijing 100084China School of Atmospheric Sciences Sun Yat-sen Universityand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Faculty of Architecture The University of Hong KongPokfulam RoadHong KongChina

During the coronavirus disease 2019 pandemic,short-range virus transmission has been observed to have a higher risk of causing infection than long-range virus transmission.However,the roles played by the inhalation and large droplet routes cannot be distinguished in practice.A recent analytical study revealed the predominance of short-range inhalation over the large droplet spray route as causes of respiratory infections.In the current study,short-range exposure was analyzed via Computational fluid dynamics(CFD)simulations using a discrete phase model.Detailed facial membranes,including eyes,nostrils,and a mouth,were considered.In CFD simulations,there is no need for a spherical approximation of the human head for estimating deposition nor the“anisokinetic aerosol sampling”approximation for estimating inhalation in the analytical model.We considered two scenarios(with two spheres[Scenario 1]and two human manikins[Scenario 2]),source-target distances of 0.2 to 2 m,and droplet diameters of 3 to 1,500μm.The overall CFD exposure results agree well with data previously obtained from a simple analytical model.The CFD results confirm the predominance of the short-range inhalation route beyond 0.2 m for expiratory droplets smaller than 50μm during talking and coughing.A critical droplet size of 87.5μm was found to differentiate droplet behaviors.The number of droplets deposited on the target head exceeded those exposed to facial membranes,which implies a risk of exposure through the immediate surface route over a short range.

关键词： airborne transmission close contact short-range inhalation large droplet spray Computational fluid dynamics

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Double-skin façade simulation with Computational fluid dynamics:A review of simulation trends,validation methods and research gaps

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Building Simulation 2023年第12期16卷 2307-2331页

作者： Simon Pommerencke Melgaard Ivan Titov Nikolaisson Chen Zhang Hicham Johra Olena Kalyanova Larsen Department of the Built Environment Aalborg UniversityDenmarkThomas Manns Vej 239220 AalborgDenmark

Dynamic simulation of a double-skin façade(DSF)with Computational fluid dynamics(CFD)can be challenging due to the lack of validated models and benchmarking datasets.Furthermore,there is a lack of consensus in the scientific community on what constitutes a successfully validated DSF model.The present review study identifies simulation trends and research gaps for DSFs simulated with CFD.Additionally,this article presents a series of CFD simulations in which key aspects of the DSF modelling are varied:2D or 3D modelling approaches,turbulence viscosity models(TVMs),radiation models,and wall function.These simulation results are compared to the empirical data(both temperature and velocity fields)of a benchmark test with laboratory-controlled boundary conditions.This analysis shows that using the k-εRNG model with enhanced wall treatment and surface-to-surface(S2S)radiation model yields the best results for the 2D case of natural convection flow.Moreover,it is shown that accounting for the velocity field in the validation process is essential to ensure the suitability of a model.Finally,the authors advocate for the use of selected dimensionless numbers to improve the comparability of the different DSF scientific studies.This would also help to identify relevant experimental datasets for validation and suitable CFD simulation settings for specific DSF cases.

关键词： double-skin facade ventilated cavity Computational fluid dynamics empirical validation modelling parameters dimensionless numbers convection

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A simplified approach to modelling blasts in Computational fluid dynamics (CFD)

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Defence Technology（防务技术） 2023年第5期23卷 19-34页

作者： D.Mohotti K.Wijesooriya S.Weckert School of Engineering and Information Technology The University of New South WalesCanberraACT2600Australia Sensors and Effectors Division Defence Science and Technology GroupEdinburghSA5111Australia

This paper presents a time-efficient numerical approach to modelling high explosive(HE)blastwave propagation using Computational fluid dynamics(CFD).One of the main issues of using conventional CFD modelling in high explosive simulations is the ability to accurately define the initial blastwave properties that arise from the ignition and consequent explosion.Specialised codes often employ Jones-Wilkins-Lee(JWL)or similar equation of state(EOS)to simulate blasts.However,most available CFD codes are limited in terms of EOS modelling.They are restrictive to the Ideal Gas Law(IGL)for compressible flows,which is generally unsuitable for blast simulations.To this end,this paper presents a numerical approach to simulate blastwave propagation for any generic CFD code using the IGL EOS.A new method known as the Input Cavity Method(ICM)is defined where input conditions of the high explosives are given in the form of pressure,velocity and temperature time-history curves.These time history curves are input at a certain distance from the centre of the charge.It is shown that the ICM numerical method can accurately predict over-pressure and impulse time history at measured locations for the incident,reflective and complex multiple reflection scenarios with high numerical accuracy compared to experimental measurements.The ICM is compared to the Pressure Bubble Method(PBM),a common approach to replicating initial conditions for a high explosive in Finite Volume modelling.It is shown that the ICM outperforms the PBM on multiple fronts,such as peak values and overall overpressure curve shape.Finally,the paper also presents the importance of choosing an appropriate solver between the Pressure Based Solver(PBS)and Density-Based Solver(DBS)and provides the advantages and disadvantages of either choice.In general,it is shown that the PBS can resolve and capture the interactions of blastwaves to a higher degree of resolution than the DBS.This is achieved at a much higher computational cost,showing that the DBS is much preferred for qui

关键词： Blast loads Computational fluid dynamics Explosions Numerical simulations

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A Computational fluid dynamics investigation of a novel flooded-bed dust scrubber with vibrating mesh

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International Journal of Mining Science and Technology 2022年第3期32卷 525-537页

作者： Zhaokuan Lu Aishwarya Rath Seyed Hassan Amini Aaron Noble Shima Shahab Department of Mechanical Engineering Virginia Polytechnic Institute and State UniversityBlacksburgVA 24061USA Department of Mining Engineering West Virginia UniversityMorgantownWV 26506USA Department of Mining and Minerals Engineering Virginia Polytechnic Institute and State UniversityBlacksburgVA 24061USA

This work proposes a vibrating mesh screen as an alternative to the static mesh screen currently used in conventional flooded-bed dust scrubbers for removing airborne coal mine dust in the continuous mining environment.Fundamental assessments suggest that a vibrating screen may improve the dust collection efficiency of scrubber systems and mitigate the clogging issues associated with the conventional design.To evaluate this hypothesis,Computational fluid dynamics(CFD)simulations were carried out to assess the effects of vibration conditions(i.e.,frequency and amplitude)on the dust particle-mesh interaction and mesh wetting conditions,which are the two decisive factors in determining the dust collection efficiency.The results suggest that the vibrating mesh screen can enhance dust particle collision opportunities on the mesh and increase mesh wetted area as compared to the static mesh screen.The effects of mesh screen aperture,coal dust concentration,and spray nozzle flow rate on the performance of the vibrating mesh are also evaluated.Finally,a simplified three-phase flow simulation including airflow,dust particles,and water droplet spray is performed,and the results reflect a significant improvement of dust collection efficiency in the liquid-coated vibrating mesh screen.

关键词： Dust control Air filtration Flooded-bed scrubber Vibrating mesh filter Continuous miner Computational fluid dynamics Multiphase flow

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Computational fluid dynamics simulation of gas dispersion in complex facilities using Kit Fox field experiments:Validation and statistical evaluation

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Chinese Journal of Chemical Engineering 2022年第4期35卷 412-423页

作者： Narjes Hemati Alam Eslam Kashi Razieh Habibpour Department of Chemical Technologies Iranian Research Organization for Science and TechnologyP.O.Box 33535111TehranIran

Gas release and its dispersion is a major concern in chemical industries.In order to manage and mitigate the risk of gas dispersion and its consequences,it is necessary to predict gas dispersion behavior and its concentration at various locations upon emission.Therefore,models and commercial packages such as Phast and ALOHA have been developed.Computational fluid dynamics(CFD)can be a useful tool to simulate gas dispersion in complex areas and conditions.The validation of the models requires the employment of the experimental data from filed and wind tunnel experiments.It appears that the use of the experimental data to validate the CFD method that only includes certain monitor points and not the entire domain can lead to unreliable results for the intended areas of concern.In this work,some of the trials of the Kit Fox field experiment,which provided a wide-range database for gas dispersion,were simulated by CFD.Various scenarios were considered with different mesh sizes,physical conditions,and types of release.The results of the simulations were surveyed in the whole domain.The data matching each scenario was varied by the influence of the dominant displacement force(wind or diffusivity).Furthermore,the statistical parameters suggested for the heavy gas dispersion showed a dependency on the lower band of gas concentration.Therefore,they should be used with precaution.Finally,the results and computation cost of the simulation could be affected by the chosen scenario,the location of the intended points,and the release type.

关键词： Gas dispersion simulation Computational fluid dynamics Complex terrain Obstructed flow

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Intelligent Control of Cabin Environment Using Computational fluid dynamics for Intelligent Manufacturing

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fluid dynamics & Materials Processing 2022年第3期18卷 563-576页

作者： Xi Wang Guangping Zeng School of Computer and Communication Engineering University of Science and Technology BeijingBeijing100083China

An efficient and versatile intelligent algorithm is developed for the control of the cabin environment of wind power generators.The method can be used to monitor and solve wind power generation problems at the same time.It also provides several advantages with respect to other traditional methods which imply significant workload and maintenance personnel.The functional requirements of the intelligent control system are analyzed,and a control algorithm for the stepping motor is selected and evaluated.Through the comparative analysis of the active power and internal temperature curve for three kinds of output power of the prototype,it is proved that the environmental intelligent control system greatly improves the operation efficiency,solves typical problems in the ventilator room environment,and provides a solid theoretical basis for further research in this field.

关键词： Wind turbine cabin environment control system Computational fluid dynamics

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Optimization of the Internal Circulating fluidized Bed Using Computational fluid dynamics Technology

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fluid dynamics & Materials Processing 2022年第2期18卷 303-312页

作者： Xiangxi Du Muyun Liu Yanhua Sun School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an710049China Shenzhen Cellauto Automation Co. Ltd.ShenzhenChina

The Computational fluid dynamics(CFD)technology is analyzed and calculated utilizing the turbulence model and multiphase flow model to explore the performance of internal circulating fluidized beds(ICFB)based on CFD.The three-dimensional simulation method can study the hydrodynamic properties of the ICFB,and the performance of the fluidized bed is optimized.The fluidization performance of the ICFB is improved through the experimental study of the cross-shaped baffle.Then,through the cross-shaped baffle and funnel-shaped baffle placement,the fluidized bed reaches a coupled optimization.The results show that CFD simulation technology can effectively improve the mass transfer efficiency and performance of sewage treatment.The base gap crossshaped baffle can improve the hydraulic conditions of the fluidized bed and reduce the system energy consumption.The cross-shaped baffle and funnel-shaped baffle can perfect the performance of the reactor and effectively strengthen the treatment in the intense aerobic process of industrial sewage.

关键词： Internal circulating fluidized bed Computational fluid dynamics optimization design internal

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Quantum Implementation of Numerical Methods for Convection-Diffusion Equations:Toward Computational fluid dynamics

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Communications in computational Physics 2023年第2期33卷 425-451页

作者： Bofeng Liu Lixing Zhu Zixuan Yang Guowei He LNM Institute of MechanicsChinese Academy of SciencesBeijing 100190China Department of Modern Mechanics University of Science and Technology of ChinaHefei 230027China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China.

We present quantum numerical methods for the typical initial boundary value problems(IBVPs)of convection-diffusion equations in fluid dynamics.The IBVP is discretized into a series of linear systems via finite difference methods and explicit time marching schemes.To solve these discrete systems in quantum computers,we design a series of quantum circuits,including four stages of encoding,amplification,adding source terms,and incorporating boundary conditions.In the encoding stage,the initial condition is encoded in the amplitudes of quantum registers as a state vector to take advantage of quantum algorithms in space complexity.In the following three stages,the discrete differential operators in classical computing are converted into unitary evolutions to satisfy the postulate in quantum systems.The related arithmetic calculations in quantum amplitudes are also realized to sum up the increments from these stages.The proposed quantum algorithm is implemented within the open-source quantum computing framework Qiskit[2].By simulating one-dimensional transient problems,including the Helmholtz equation,the Burgers’equation,and Navier-Stokes equations,we demonstrate the capability of quantum computers in fluid dynamics.

关键词： Quantum computing partial differential equations Computational fluid dynamics finite difference finite element.

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AMMONIA DISPERSION FROM MULTI-FLOOR VERSUS STANDARD SINGLE-FLOOR PIG PRODUCTION FACILITIES BASED ON Computational fluid dynamics SIMULATIONS

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Frontiers of Agricultural Science and Engineering 2023年第3期10卷 374-389页

作者： Yicong XIN Li RONG Gunther SCHAUBERGER Dejia LIU Xiusong LI Zhihua YANG Songming ZHU Dezhao LIU Key Laboratory of Equipment and Informatization in Environment Controlled Agriculture Ministry of Agriculture and Rural AffairsKey Laboratory of Intelligent Equipment and Robotics for Agriculture of Zhejiang ProvinceInstitute of Agricultural Bio-Environmental EngineeringCollege of Biosystems Engineering and Food ScienceZhejiang UniversityHangzhou 310058China Department of Civil and Architectural Engineering—Building Science Aarhus UniversityAarhus C 8000Denmark WG Environmental Health Unit for Physiology and BiophysicsUniversity of Veterinary MedicineA-1210 ViennaAustria Big Herdsman Machinery Co. Ltd.Qingdao 266000China Zhejiang Huatong Meat Products Co. Ltd.Yiwu 322000China

Multi-floor buildings for raising pigs have recently attracted widespread attention as an emerging form of intensive livestock production especially in eastern China,due to the fact that they can feed a much larger number of animals per unit area of land and thus alleviate the shortage of land available for standard single-floor pig production facilities.However,this more intensive kind of pig building will pose new challenges to the local environment in terms of pollutant dispersion.To compare the dispersion air pollutants(ammonia as a representative)emitted from multi-versus single-floor pig buildings,ammonia dispersion distance and concentration gradients were investigated through three-dimensional simulations based on Computational fluid dynamics.The validation of an isolated cubic model was made to ensure the simulation method was effective.The effects of wind direction,wind speed and emission source concentration at 1.5 m(approximate human inhalation height)during summer were investigated.The results showed that the ammonia dispersion distance of the multi-floor pig building was far greater than that of the single-floor building on a plane of Z=1.5 m.When the wind direction was 67.5°,the wind speed was 2 m·s^(−1) and the emission source concentration was 20 ppmv,the dispersion distance of the multi-floor pig building could reach 1380 m.Meanwhile,the ammonia could accumulate in the yard to 7.68 ppmv.Therefore,future site selection,wind speed and source concentration need to be given serious consideration.Based on the simulation used in this study with source concentration is 20 ppmv,the multi-floor pig buildings should be located 1.4 km away from residential areas to avoid affecting residents.The results of this study should guidance for any future development of multi-floor pig buildings.

关键词： pig building Computational fluid dynamics ammonia dispersion

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Non-invasive assessment of intracranial wall shear stress using high-resolution magnetic resonance imaging in combination with Computational fluid dynamics technique

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Fundamental Research 2022年第2期2卷 329-334页

作者： Yuwen Chen Jia Liu Mingli Li Yannan Yu Zhengzheng Yan Wenshin Shiu Bokai Wu Zaiheng Cheng Yao Meng Yang Liu Weizhuang Yuan Zongmuyu Zhang Weihai Xu Department of Neurology State Key Laboratory of Complex Severe and Rare DiseasesPeking Union Medical Cllege HospitalChinese Academy of Medical Sciences and Peking Union Medical College1 ShuaifuyuanBeijing 100005China Department of Cardiology Second Afliated Hospital of Zhejiang University School of MedicineHangzhouZhejiang 310009China Shenzhen Instiutes of Advanced Technology Chinese Academy of SciencesShenzhen 518055China Shenzhen Key Laboratory for Exascale Engineering and Scientific Computing Shenzhen 518055China Department of Radiology Peking Union Medical College HospitalChinese Acadermy of Medical Sciences1 ShuaifiryuanBeijing 100005China Department of Radiology Stanford UniversityCaliformia 94305United States Department of Neurology Saarland UniversityKirrberger StraSe 66421Germany

In vivo studies on association between wall shear stress(WSS)and intracranial plaque are deficient.Based on the three-dimensional T1-weighted high-resolution magnetic resonance imaging(3DT1 HR-MRI)data of patients with low-grade stenotic(Computational fluid dynamics(CFD)technique.Three-dimensional registration of the CFD model to the HR-MRI was performed with projections based on the resolution and thickness of the images.The relationships between the Wss at each side of the vessel wall and plaque location were analyzed.A total of 94 MCA plaques from 43 patients and 50 normal MCAs were analyzed.In the normal MCAs,WSS was lower at the ventral-inferior wall than at the dorsal-superior wall(proximal segment,p<0.001;middle segment,p<0.001)and lower at the inner wall than at the outer wall of the MCA curve(p<0.001).In atherosclerotic MCAs,similar low Wss regions were observed where plaques developed.The WSS ratio of the ventral-inferior wall to the dorsal-superior wall in atherosclerotic MCAs was lower than that in normal MCAs(p=0.002).The WSS_(inmer-outer)ratio in atherosclerotic MCAs was lower than that in normal MCAs(p=0.002).Low WSS was associated with MCA atherosclerosis formation and occurred mainly at the ventral inferior wall,which was anatomically opposite the orifices of penetrating arteries,and at the inner wall of the MCA curve.Overall,the results were well consistent with the low WSS theory in atherosclerosis formation.The reconstructed WSS model is a promising novel method for assessing an individualized vascular profile once validated by further studies.

关键词： Intracranial atherosclerosis Wall shear stress Atherosclerotic plaque High-resolution magnetic resonance imaging Computational fluid dynamics

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