Airflow Patterns Research Articles

Development of non-isothermal wall jet integrated zonal model with enhanced accuracy using a multi-flow coefficient calibration method

A zonal model is an intermediate model between a nodal model and a computational fluid dynamics (CFD) model. This type of models has been widely used to predict indoor temperature distribution and airflow patterns by compromising prediction accuracy and computational efficiency. However, the zonal model was mainly used to predict the indoor environment of rooms with natural convection or isothermal air supply in previous literature, neglecting its application in non-isothermal air supply. Since driving flow under non-isothermal air supply is more common in air-conditioned spaces, this paper proposes a jet-integrated zonal model (JIZM) to predict the indoor environment of rooms with non-isothermal wall jet supply, extending the applicability of the zonal modelling technique. Meanwhile, a multi-flow coefficient calibration method was developed to improve the performance of the JIZM using a multi-objective genetic algorithm (MOGA). The applicability of the JIZM was evaluated under typical air supply scenarios. The results demonstrated that the JIZM with the proposed calibration method is able to using limited measurement data with calibrated model parameters to predict the air distributions with reasonable accuracy in a fast way, thus offering a better technique in predicting the vertical temperature distribution in air-conditioned rooms compared with a conventional zonal model.

Computational Fluid Dynamics Simulations to Assess Spatial Variability and Optimal Ventilation Scenarios for Biological Laboratory Exposures

Introduction: A significant amount of uncertainty exists regarding potential human exposure to laboratory biomaterials and organisms in Biosafety Level 2 (BSL-2) research laboratories. Computational fluid dynamics (CFD) modeling is proposed as a way to better understand potential impacts of different combinations of biomaterials, laboratory manipulations, and exposure routes on risks to laboratory workers. Methods: In this study, we use CFD models to simulate airborne concentrations of contaminants in an actual BSL-2 laboratory under different configurations. Results: Results show that ventilation configuration, sampling location, and contaminant source location can significantly impact airborne concentrations and exposures. Depending on the source location and airflow patterns, the transient and time-integrated concentrations varied by several orders of magnitude. Contaminant plumes from sources located near a return vent (or exhaust like a fume hood or ventilated biosafety cabinet) are likely to be more contained than sources that are further from the exhaust. Having a direct flow between the source and the exhaust (through-flow condition) may reduce potential exposures to individuals outside the air flow path. Conclusion: Designing a BSL-2 room with ventilation and airflow patterns that maximize through-flow conditions to the return/exhaust vents and minimize dispersion and mixing throughout the room is, therefore, recommended. CFD simulations can also be used to assist in characterizing the impacts of supply and return vent locations, room layout, and source locations on spatial and temporal contaminant concentrations. In addition, proper placement of particle sensors can also be informed by CFD simulations to provide additional characterization and monitoring of potential exposures in BSL-2 facilities.

How Sterile Are Our Operating Rooms? A Comparison of Air Quality During Primary TKA and THA

Introduction: Airborne Biologic Particles (ABPs) are a potential risk factor for infection following total joint arthroplasty. Factors such as temperature and humidity may affect the number of ABPs which can increase the risk of infection. Comparisons of ABP count between Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA) have yet to be made. Our study examines the differences in ABP count between primary THA and TKA procedures. Methods: We analyzed all primary TJA procedures done within the same OR at an academic institution from April 2019 to June 2020. All procedures between the dates of March 15, 2020 – May 4, 2020 were excluded to avoid COVID-related confounding. Intraoperative measurements of temperature, humidity, and ABP count per minute were recorded. A report containing surgical data from the same time was generated using the institution’s Electronic Health Records (EHR) system and cross-referenced to the intraoperative measurements using procedure start and end times. ABP was calculated as an average ABP count per minute. Descriptive statistics were used to evaluate differences in variables of interest. P-values were calculated using t-test for continuous variables and chi square for categorical values. Results: A total of 168 cases were included in the study, comprised of 98 (58.3%) primary THA and 70 (41.7%) primary TKA. No significant differences in room temperature or particle counts across all particle sizes were found between THA and TKA groups. Similarly, time spent in the room was not significantly different between THA and TKA. The only variable that was significantly different between the two groups was average relative humidity, with higher humidity in the THA group (46.9% + 7.56 vs 44.4% + 8.02, p=0.008). Conclusion: There were no significant differences in temperature or particle count between primary THA and primary TKA procedures, suggesting OR air quality was similar between the two procedure types. Further investigation including additional variables such as OR size, airflow patterns, and different procedure types should be performed to better characterize the role of ABPs in air quality and infection risk.

Evaluation of the Effects of Airflow Patterns on Human Thermal Perception

Recently, greenhouse gas emissions have led to irreversible climate change, and in order to mitigate the changes, more and more research is focusing on energy efficiency and environmental protection in the building sector. Improving indoor ventilation airflow as a feasible solution for energy conservation as well as improving human thermal comfort. This study aims to provide reference for optimizing the thermal perception of occupants in indoor ventilation design. This research evaluates the effect of heat perception on students in a stable indoor environment (28 ℃, RH 50%) under two airflow patterns (dynamic and constant). The use of airflow was found to have a positive impact on thermal sensation vote (TSV) and thermal pleasure vote (TPV). There was non-significant difference in the effects of heat perception between airflow modes. This finding is consistent with the findings of Parkinson and de Dear's study. It is worth noting that differences in experimental results may be due to other personal factors (e.g., gender, age, and weight). Further studies are therefore needed to demonstrate the influence of these factors on the thermal perception effect of air movement.

Large-eddy simulation of airflow dynamics around a cluster of buildings

The wind flow around the buildings with different rooftops is studied numerically using large-eddy simulation (LES). The filtered Navier-Stokes equations in LES are used to compute the large eddies, whereas the dynamic Smagorinsky subgrid-scale (SGS) model calculates the small eddies. A turbulent spot method is applied for the synthesis of artificial turbulent fields at the inlet. In this separated and reattached flow, our aim is to analyze the wakes’ vortical structure along with the buildings of different heights and shapes. A large number of engineering applications involve precise predictions of the airflow around buildings to ensure performance and safety. To validate the numerical solver, a comparison is performed with the earlier reported numerical and experimental data. The turbulent flow characteristics are discussed in terms of instantaneous flow structure and time-averaged statistical flow quantities. All the cases are simulated for a Reynolds number [Formula: see text] to understand the turbulent airflow patterns. The flow shows a separable bubble at the leading edge of the rooftop of the building that leads to recirculation at the lee side of the first row of buildings. Due to the recirculation, the suction arises near the leading edge of the building to assure a continuous flow of air around the obstacles. Further, Reynold stresses show high momentum fluxes in the frontal region of the buildings.

Impact of sinonasal anatomic changes after endoscopic anterior skull base surgery on nasal airflow and air conditioning: a computational fluid dynamics study

Objective: To analyze the impact of the sinonasal anatomic changes after endonasal endoscopic anterior skull base surgery on the nasal airflow and heating and humidification by computational fluid dynamics (CFD), and to explore the correlation between the postoperative CFD parameters and the subjective symptoms of the patients. Methods: The clinical data in the Rhinology Department of the First Affiliated Hospital of Zhengzhou University from 2016 to 2021 were retrospectively analyzed. The patients received the endoscopic resection of the anterior skull base tumor were selected as the case group, and the adults whose CT scans had no sinonasal abnormalities were chosen as the control group. The CFD simulation was performed on the sinonasal models after reconstructed from the patients' sinus CT images during the post-surgical follow-up. All the patients were asked to complete the Empty Nose Syndrome 6-Item Questionnaire (ENS6Q) to assess the subjective symptoms. The comparison between two independent groups and the correlation analysis were carried out by using the Mann-Whitney U test and the Spearman correlation test in the SPSS 26.0 software. Results: Nineteen patients (including 8 males and 11 females, from 22 to 67 years old) in the case group and 2 patients (a male of 38 years old and a female of 45 years old) in the control group were enrolled in this study. After the anterior skull base surgery, the high-speed airflow moved to the upper part of the nasal cavity, and the lowest temperature shifted upwards on the choana. Comparing with the control group, the ratio of nasal mucosal surface area to nasal ventilation volume in the case group decreased [0.41 (0.40, 0.41) mm-1 vs 0.32 (0.30, 0.38) mm-1; Z=-2.04, P=0.041], the air flow in the upper and middle part of the nasal cavity increased [61.14 (59.78, 62.51)% vs 78.07 (76.22, 94.43)%; Z=-2.28, P=0.023], the nasal resistance decreased [0.024 (0.022, 0.026) Pa·s/ml vs 0.016 (0.009, 0.018) Pa·s/ml; Z=-2.29, P=0.022], the lowest temperature in the middle of the nasal cavity decreased [28.29 (27.23, 29.35)℃ vs 25.06 (24.07, 25.50)℃; Z=-2.28, P=0.023], the nasal heating efficiency decreased [98.74 (97.95, 99.52)% vs 82.16 (80.24, 86.91)%; Z=-2.28, P=0.023], the lowest relative humidity decreased [(79.62 (76.55, 82.69)% vs 73.28 (71.27, 75.05)%; Z=-2.28, P=0.023], and the nasal humidification efficiency decreased [99.50 (97.69, 101.30)% vs 86.09 (79.33, 87.16)%; Z=-2.28, P=0.023]. The ENS6Q total scores of all patients in the case group were less than 11 points. There was a moderate negative correlation between the proportion of the inferior airflow in the post-surgical nasal cavity negatively and the ENS6Q total scores (rs=-0.50, P=0.029). Conclusions: The sinonasal anatomic changes after the endoscopic anterior skull base surgery alter the nasal airflow patterns, reducing the efficiency of nasal heating and humidification. However, the post-surgical occurrence tendency of the empty nose syndrome is weak.

Computational fluid-particle dynamics modeling of ultrafine to coarse particles deposition in the human respiratory system, down to the terminal bronchiole

Background and objectivesSuspended respirable airborne particles are associated with human health risks and especially particles within the range of ultrafine (< 0.1 μm) or fine (< 2.5 μm) have a high possibility of penetrating the lung region, which is concerned to be closely related to the bronchial or alveoli tissue dosimetry. Nature complex structure of the respiratory system requires much effort to explore and comprehend the flow and the inhaled particle dynamics for precise health risk assessment. Therefore, this study applied the computational fluid-particle dynamics (CFPD) method to elucidate the deposition characteristics of ultrafine-to-coarse particles in the human respiratory tract from nostrils to the 16th generation of terminal bronchi. MethodsThe realistic bronchi up to the 8th generation are precisely and perfectly generated from computed tomography (CT) images, and an artificial model compensates for the 9th-16th bronchioles. Herein, the steady airflow is simulated at constant breathing flow rates of 7.5, 15, and 30 L/min, reproducing human resting-intense activity. Then, trajectories of the particle size ranging from 0.002 – 10 μm are tracked using a discrete phase model. ResultsHere, we report reliable results of airflow patterns and particle deposition efficiency in the human respiratory system validated against experimental data. The individual-related focal point of ultrafine and fine particles deposition rates was actualized at the 8th generation; whilst the hot-spot of the deposited coarse particles was found in the 6th generation. Lobar deposition characterizes the dominance of coarse particles deposited in the right lower lobe, whereas the left upper-lower and right lower lobes simultaneously occupy high deposition rates for ultrafine particles. Finally, the results indicate a higher deposition in the right lung compared to its counterpart. ConclusionsFrom the results, the developed realistic human respiratory system down to the terminal bronchiole in this study, in coupling with the CFPD method, delivers the accurate prediction of a wide range of particles in terms of particle dosimetry and visualization of site-specific in the consecutive respiratory system. In addition, the series of CFPD analyses and their results are to offer in-depth information on particle behavior in human bronchioles, which may benefit health risk assessment or drug delivery studies

Investigation of flow distribution in energy intensive aluminium production reduction cells: An exploratory study

The process of making aluminium often involves electrolytic cells, also known as reduction cells. The reduction cell exhaust manifolds must achieve a steady distribution of exhaust from each cell in the network. This will prevent fugitive pollutants, which are harmful to both human and environmental health. While ducts are adjusted to achieve appropriate flow rates, they become asymmetrical over time. A few case studies available in the literature that discuss the flow distribution in an electrolytic cell, and almost none provide insight into the operational flow distribution of reduction cells in service. As part of this study, the operating flow distribution in service reduction cells is examined, determined which factors contribute to poor gas patterns produced by reduction line cells and analysed the flow conditions that result in sediment deposition within the ducting that connects the reduction cells to the superstructure, which is the novelty of this case study. Various instruments were used to record the temperature and pressure of a smelting facility. Flow information for each cell was collected using Pitot traverses. Infrared thermography of the ducts was used to locate temperature anomalies and possible areas of particle build-up. These tests indicated a number of probable contributing causes that have contributed to the inadequate airflow pattern from each reduction cell.

Evaluation of CFD-predicted thermal comfort uncertainties based on a seated thermal manikin test case

The contribution presents the results of numerical simulation of 3D turbulent airflow and heat transfer around a seated thermal manikin in a model room with mixing ventilation. The main goal of the study is to evaluate the uncertainties caused by a CFD model. The room and the detailed thermal manikin geometry correspond to the experiment of P.V. Nielsen et al. (2007). The 3D computational model based on the RANS approach with the standard k-ε turbulence model is applied. The radiation effects are taken into account with the surface-to-surface radiation model. The study considers (1) the effect of the supply air flow rate variation and (2) the effect of the thermal manikin geometrical shape. For a particular parameters set, the results of numerical simulation are validated using the experimental data available (P.V. Nielsen et al.). The contribution is focused also on studying the effects of various heat transfer mechanisms on the airflow pattern and thermal comfort parameters: the baseline mixing ventilation scenario is compared with the buoyancy-dominated case.

Remote sensing of indoor thermal environment from outside the building through window opening gap by using infrared camera.

Investigation of housing indoor temperature is important for understanding the comfort, health and living conditions of the local residents. The traditional method to measure indoor temperature is to place sensors at the target places, which is not only expensive but also inconvenient for indoor temperature investigation, especially for the investigation at community and city scale. In this study, a novel method was proposed to obtain the indoor temperatures remotely from outside the building through window opening area using and infrared camera. Compared with the traditional contact measurement method, the proposed remote sensing method could detect the indoor temperature without entering the room. Moreover, the infrared image could reflect the spatial distribution information of indoor temperature. To verify the feasibility and accuracy of this method, an experiment was conducted in a test room under heating, transitional, and cooling conditions with various window opening grades. It was found that the infrared images at the window opening area could reflect the spatial distribution of indoor temperature with an accuracy within 0.5 °C under stable heating and transitional conditions. In the fan coil cooling condition, however, although the infrared image can reflect the cold air flow pattern, the deviations between the infrared temperature and the measured room temperature exceeded 1.0 °C. The effect of window opening grade on the recognition accuracy kept within 0.5 °C.

Standard precautions should include 'safe ventilation' to minimise far-afield airborne transmission in health and social care settings.

Standard precautions should include 'safe ventilation' to minimise far-afield airborne transmission in health and social care settings.

Impacts of Development, Dentofacial Disharmony, and Its Surgical Correction on Speech: A Narrative Review for Dental Professionals.

Speech is a communication method found only in humans that relies on precisely articulated sounds to encode and express thoughts. Anatomical differences in the maxilla, mandible, tooth position, and vocal tract affect tongue placement and broadly influence the patterns of airflow and resonance during speech production. Alterations in these structures can create perceptual distortions in speech known as speech sound disorders (SSDs). As craniofacial development occurs, the vocal tract, jaws, and teeth change in parallel with stages of speech development, from babbling to adult phonation. Alterations from a normal Class 1 dental and skeletal relationship can impact speech. Dentofacial disharmony (DFD) patients have jaw disproportions, with a high prevalence of SSDs, where the severity of malocclusion correlates with the degree of speech distortion. DFD patients often seek orthodontic and orthognathic surgical treatment, but there is limited familiarity among dental providers on the impacts of malocclusion and its correction on speech. We sought to review the interplay between craniofacial and speech development and the impacts of orthodontic and surgical treatment on speech. Shared knowledge can facilitate collaborations between dental specialists and speech pathologists for the proper diagnosis, referral, and treatment of DFD patients with speech pathologies.

Influence of natural ventilation design on the dispersion of pathogen-laden droplets in a coach bus

Natural ventilation is an energy-efficient design approach to reduce infection risk (IR), but its optimized design in a coach bus environment is less studied. Based on a COVID-19 outbreak in a bus in Hunan, China, the indoor-outdoor coupled CFD modeling approach is adopted to comprehensively explore how optimized bus natural ventilation (e.g., opening/closing status of front/middle/rear windows (FW/MW/RW)) and ceiling wind catcher (WCH) affect the dispersion of pathogen-laden droplets (tracer gas, 5 μm, 50 μm) and IR. Other key influential factors including bus speed, infector's location, and ambient temperature (Tref) are also considered. Buses have unique natural ventilation airflow patterns: from bus rear to front, and air change rate per hour (ACH) increases linearly with bus speed. When driving at 60 km/h, ACH is only 6.14 h−1 and intake fractions of tracer gas (IFg) and 5 μm droplets (IFd) are up to 3372 ppm and 1394 ppm with ventilation through leakages on skylights and no windows open. When FW and RW are both open, ACH increases by 43.5 times to 267.50 h−1, and IFg and IFd drop rapidly by 1–2 orders of magnitude compared to when no windows are open. Utilizing a wind catcher and opening front windows significantly increases ACH (up to 8.8 times) and reduces IF (5–30 times) compared to only opening front windows. When the infector locates at the bus front with FW open, IFg and IFd of all passengers are <10 ppm. More droplets suspend and further spread in a higher Tref environment. It is recommended to open two pairs of windows or open front windows and utilize the wind catcher to reduce IR in coach buses.

The airflow distribution and aerosol diffusion rules in the negative pressure isolation ward

Negative pressure wards are significant in preventing the spread of infectious pathogens which play a crucial role in fighting against COVID-19. Owing to the negative pressure, contaminated air with pathogens is not able to flow from the wards to non-contaminated zones while fresh filtered air will be transported to the ward via the ventilation system. As airflow controlled by ventilation systems affects the motion of pathogens, for example, infectious aerosol particles, the ability of a negative pressure ward to reduce the risk of infection highly relies on an effective ventilation system. In this investigation, impacts of airflow patterns under various human postures and ventilation processes aerosols diffusion are analyzed via the computational fluid dynamics (CFD) simulation. According to the results, among three airflow patterns, the highest contaminant removal efficiency is 57% at 200 s with the top supply and bottom return mode; besides, in three postures, in the case that the patient is in a standing position, the contaminant removal efficiency is the highest. Furthermore, it is found that the best airflow scheme is a slit tuyere in the ward, with a top supply and side return mode and a sitting position for the patient. This study may provide a reference for the design of airflow in negative pressure isolation wards, control of contaminants, and prevention of viral infections, so as to ensure a good working and recovery environment for medical staff and patients.

Condensation heat transfer between a vertical superhydrophobic aluminum surface and moist air under natural convection

Condensation heat transfer at superhydrophobic surfaces has raised a lot of interest due to their potential application in atmospheric water harvesting and air-conditioning. In moist air, the condensation heat transfer using a superhydrophobic surface can be negatively affected by the existence of a large amount of non-condensable gas, namely, the dry air. Besides, the air flow pattern would substantially affect the surface condensation rate due to the convective mass transfer of water vapor. In this study, the condensation regime of a superhydrophobic aluminum surface vertically positioned in quiescent moist air was visualized and the condensation rate was experimentally investigated. Condensation experiments were also performed by using hydrophobic, hydrophilic, and superhydrophilic surfaces for comparison. The condensation rate of the superhydrophobic surface was consistent with that of other surfaces, though the condensation regimes of the four surfaces were quite different. The average deviation between the experimental condensation rate and the empirical correlation of natural convection heat and mass transfer was within 12%. The result indicates that vapor transfer induced by diffusion and convection in the boundary layer rather than the heat transfer resistance associated with condensate dominates the condensation heat and mass transfer between the moist air and the superhydrophobic surface.

A Novel IoT-Enabled Wireless Sensor Grid for Spatial and Temporal Evaluation of Tracer Gas Dispersion.

Current IoT applications in indoor air focus mainly on general monitoring. This study proposed a novel IoT application to evaluate airflow patterns and ventilation performance using tracer gas. The tracer gas is a surrogate for small-size particles and bioaerosols and is used in dispersion and ventilation studies. Prevalent commercial tracer-gas-measuring instruments, although highly accurate, are relatively expensive, have a long sampling cycle, and are limited in the number of sampling points. To enhance the spatial and temporal understanding of tracer gas dispersion under the influence of ventilation, a novel application of an IoT-enabled, wireless R134a sensing network using commercially available small sensors was proposed. The system has a detection range of 5-100 ppm and a sampling cycle of 10 s. Using Wi-Fi communication, the measurement data are transmitted to and stored in a cloud database for remote, real-time analysis. The novel system provides a quick response, detailed spatial and temporal profiles of the tracer gas level, and a comparable air change rate analysis. With multiple units deployed as a wireless sensing network, the system can be applied as an affordable alternative to traditional tracer gas systems to identify the dispersion pathway of the tracer gas and the general airflow direction.

Understanding airflow pattern and temperature distribution in domestic refrigerators – A review analyzing recent developments and bridging knowledge gaps

Refrigerators have become an essential appliance in every household, and they consume approximately 30% of total electricity among other domestic appliances such as clothes washers, dryers, and air conditioners. With the refrigerator’s comparatively high energy consumption compared with other appliances, existing research has mainly focused on improving the energy efficiency of refrigerators by changing the design of the compressor, heat exchanger, refrigerant, and insulation. However, previous studies have paid very little attention to the research and development of the temperature distribution in the refrigerator, which is a key parameter in determining energy consumption and food safety. Therefore, this review aims to present an overview of recent design developments to improve the temperature distribution and air circulation in domestic refrigerators, including static refrigerators and no-frost refrigerators. This review article discusses the various operation and design factors that can affect the air circulation and temperature uniformity of the refrigerator, including shelf arrangement, the compressor on/off cycle, thermostat settings, evaporator design, ambient conditions, door opening frequency, and product loading temperatures. Additionally, this review provides a summary of the advanced vapor compression cycle based refrigerators that are expected to provide better energy efficiency and independent temperature control in freezer and refrigerator compartments. This review elaborates on the significance of improving the performance of the domestic refrigerator in terms of temperature distribution and air circulation.

Investigating the temperature distribution of non-enclosed atriums with air infiltration in winter

Low-temperature air infiltration and vertical thermal stratification lead to an unsatisfied bottom-occupied environment of the atrium and increase the space heating load in winter. An integrated prediction model was proposed regarding the interaction between thermal stratification and air infiltration. It includes the extended Block model for predicting the vertical temperature distribution in a non-enclosed atrium, the air infiltration model for calculating the buoyancy-driven air infiltration rate, and the Velocity propagating model for describing the airflow pattern within a foyer. By applying this model, we quantitatively analysed the indoor thermal characteristics in different atrium/foyer spatial morphologies. Beyond the indoor net height, the atrium diameter is also a dominant factor affecting the flow rate of air infiltration introduced from the foyer. The lower the section aspect ratio (SAR) and the higher the bottom floor height of the atrium, the warmer the bottom-occupied environment. The foyer's buffer effect mainly promotes occupants' thermal comfort, as lengthening the foyer length increases the heating load of air infiltration into the atrium while helping reduce the horizontal temperature gradient (HTG) when occupants walk across. This study clarified the indoor environmental characteristics in such spaces in winter and explored the interrelated influencing factors. The methodology and conclusions provide insights into practical engineering.

How do caves breathe: The airflow patterns in karst underground.

Caves and their surrounding fracture systems in the vadose zone of karst regions host a unique atmospheric environment. Understanding the airflow patterns in caves is critical to understanding the properties of the subsurface atmosphere and the chemical interactions between air, water, and rock. The most common driver of airflow in caves is the density difference between the subsurface and the outside air, known as the chimney effect. Observations show that seasonal airflow patterns in caves also depend on the geometry of passages. In this work, I present and use a numerical model of a passage embedded and thermally coupled to a rock mass to study the relationship between the airflow pattern and passage geometry. As the outside air enters the subsurface, it approaches thermal equilibrium with the rock mass along a characteristic relaxation length. This determines the temperature and density contrast between the inside and outside air, and the resulting pressure difference, which drives the airflow. In passages with non-uniform outlines and/or cross-sections, the relaxation length may depend on the flow direction, resulting in different airflow velocities in cold and warm periods for the same absolute temperature difference between the massif and the external temperature. In a passage with a V-shaped longitudinal profile, the airflow is triggered by instability which causes the feedback between the relaxation length and airflow velocity. The airflow pattern can also be altered by snow and ice. Heat transfer in the rock and the thermal inertia of the rock also change the relaxation lengths and cause hysteresis in the curve presenting the airflow velocity vs. temperature difference.

Evaluation of infection probability of Covid-19 in different types of airliner cabins.

According to the World Health Organization (https://covid19.who.int/), more than 651 million people have been infected by COVID-19, and more than 6.6 million of them have died. COVID-19 has spread to almost every country in the world because of air travel. Cases of COVID-19 transmission from an index patient to fellow passengers in commercial airplanes have been widely reported. This investigation used computational fluid dynamics (CFD) to simulate airflow and COVID-19 virus (SARS-CoV-2) transport in a variety of airliner cabins. The cabins studied were economy-class with 2-2, 3-3, 2-3-2, and 3-3-3 seat configurations, respectively. The CFD results were validated by using experimental data from a seven-row cabin mockup with a 3-3 seat configuration. This study used the Wells-Riley model to estimate the probability of infection with SARS-CoV-2. The results show that CFD can predict airflow and virus transmission with acceptable accuracy. With an assumed flight time of 4h, the infection probability was almost the same among the different cabins, except that the 3-3-3 configuration had a lower risk because of its airflow pattern. Flying time was the most important parameter for causing the infection, while cabin type also played a role. Without mask wearing by the passengers and the index patient, the infection probability could be 8% for a 10-h, long-haul flight, such as a twin-aisle air cabin with 3-3-3 seat configuration.