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1.
Patient Saf Surg ; 16(1): 26, 2022 Aug 06.
Article in English | MEDLINE | ID: covidwho-2032619

ABSTRACT

BACKGROUND: Airborne transmission diseases can transfer long and short distances via sneezing, coughing, and breathing. These airborne repertory particles can convert to aerosol particles and travel with airflow. During the Coronavirus disease 2019 (COVID-19) pandemic, many surgeries have been delayed, increasing the demand for establishing a clean environment for both patient and surgical team in the operating room. METHODS: This study aims to investigate the hypothesis of implementing a protective curtain to reduce the transmission of infectious contamination in the surgical microenvironment of an operating room. In this regard, the spread of an airborne transmission disease from the patient was evaluated, consequently, the exposure level of the surgical team. In the first part of this study, a mock surgical experiment was established in the operating room of an academic medical center in Norway. In the second part, the computational fluid dynamic technique was performed to investigate the spread of airborne infectious diseases. Furthermore, the field measurement was used to validate the numerical model and guarantee the accuracy of the applied numerical models. RESULTS: The results showed that the airborne infectious agents reached the breathing zone of the surgeons. However, using a protective curtain to separate the microenvironment between the head and lower body of the patient resulted in a 75% reduction in the spread of the virus to the breathing zone of the surgeons. The experimental results showed a surface temperature of 40 ˚C, which was about a 20 ˚C increase in temperature, at the wound area using a high intensity of the LED surgical lamps. Consequently, this temperature increase can raise the patient's thermal injury risk. CONCLUSION: The novel method of using a protective curtain can increase the safety of the surgical team during the surgery with a COVID-19 patient in the operating room.

2.
Case Studies in Chemical and Environmental Engineering ; : 100257, 2022.
Article in English | ScienceDirect | ID: covidwho-2031229

ABSTRACT

Owing to the spread of COVID-19, the need for an inspection center that can quickly determine whether travelers using the airport are infected has emerged. For rapid determination, not only polymerase chain reaction tests but also antigen–antibody tests and on-site analysis systems are required. However, because it is time- and cost-intensive to construct a building that meets the standards for negative pressure facilities, modular negative pressure facilities are being installed as alternatives. Existing negative pressure facilities have problems such as increased energy consumption due to outdoor air load and condensation due to differences in indoor and outdoor temperatures and humidities caused by excessive external air inflow to achieve the target negative pressure and air change rate (ACH). In addition, owing to the installation of additional devices, additional construction is required to use them for other purposes in the future. To solve these problems, in this study, energy recovery ventilation (ERV) was employed to develop a heating, ventilation and air conditioning (HVAC) solution for the Incheon International Airport COVID-19 Testing Center. To shorten the development period, virtual product design (VPD) using computational fluid dynamics analysis-based design of experiments was performed. Owing to the application of VPD, the Incheon International Airport Modular COVID-19 Testing Center was completed in 2 weeks. The target pressure was measured in all spaces by applying the optimal conditions derived through VPD. In addition, owing to the application of ERV, the ACH of an airborne infectious isolation room exceeded the value suggested by international organizations.

3.
7th Thermal and Fluids Engineering Conference, TFEC 2022 ; 2022-May:1119-1128, 2022.
Article in English | Scopus | ID: covidwho-2027167

ABSTRACT

Aerated ponds are essential in water treatment systems. However, fecal-oral transmission is a common dissemination route for many viruses, for this reason, aerated ponds could become unsafe within the current scenario of COVID-19 global pandemic. This paper has employed a CFD approach to study how the aeration process in an aerated pond can promote possible virus transmission. An aerated pond located in a water treatment plant in the city of Guayaquil, Ecuador was studied. A two-dimensional domain was developed with a structured mesh validated with a sensitivity study. The multiphase volume-of-fluid model is used to simulate the aeration process with a k-ε realizable turbulence model, and a discrete phase model is used to model the trajectories of water droplets due to the turbulence of the aeration process. The trajectory of water droplets was modeled, reaching a maximum height of 26.3 cm above the surface of the pond with a velocity of 1.38 m/s. The effect of promoting possible virus transmission by these droplets turned out to be low, compared to other processes considered. Nevertheless, parameters such as inlet air velocity, number of aerators and air flow rate could change due to design and operating conditions of water treatment systems, resulting in a possible increase of the maximum height of the water droplets. © 2022 Begell House Inc.. All rights reserved.

4.
Building and Environment ; : 109530, 2022.
Article in English | ScienceDirect | ID: covidwho-2003904

ABSTRACT

This study used Computational Fluid Dynamics (CFD) to investigate air disinfection for SARS-CoV-2 by the Upper-Room Germicidal Ultraviolet (UR-GUV), with focus on ceiling impact. The study includes three indoor settings, i.e., low (airport bus), medium (classroom) and high (rehearsal room) ceilings, which were ventilated with 100% clean air (CA case), 80% air-recirculation with a low filtration (LF case), and 80% air-recirculation with a high filtration (HF case). According to the results, using UR-GUV can offset the increased infection risk caused by air recirculation, with viral concentrations in near field (NF) and far field (FF) in the LF case similar to those in the CA case. In the CA case, fraction remaining (FR) was 0.48–0.73 with 25% occupancy rate (OR) and 0.49–0.91 with 45% OR in the bus, 0.41 in NF and 0.11 in FF in the classroom, and 0.18 in NF and 0.09 in FF in the rehearsal room. Obviously, UR-GUV performance in NF can be improved in a room with a high ceiling where FR has a power relationship with UV zone height. As using UR-GUV can only extend the exposure time to get infection risk of 1% (T1%) to 8 min in NF in the classroom, and 47 min in NF in the rehearsal room, it is necessary to abide by social distancing in the two rooms. In addition, T1% in FF was calculated to be 18.3 min with 25% OR and 21.4% with 45% OR in the airport bus, showing the necessity to further wear a mask.

5.
AIAA AVIATION 2022 Forum ; 2022.
Article in English | Scopus | ID: covidwho-1993728

ABSTRACT

As part of the Summer High School Intensive in Next Generation Engineering (SHINE) with the University of Southern California's (USC) Viterbi School of Engineering, this work examines the transmission of the COVID-19 virus through respiratory droplets expelled from an infected individual. Social distancing and face masking protocols have been implemented to reduce the spread of droplets. This study aimed to assess the effectiveness of the recommendations using computational fluid dynamics simulations based upon the ANSYS Fluent Student Edition with two-dimensional axisymmetric simulations. The four most common ways of spreading respiratory droplets, including breathing, talking, coughing, and sneezing, were examined. Before completing the droplet spray simulations, several canonical jet flows were simulated to verify the validity of Fluent's application. Specifically, laminar and turbulent free jets were modeled and compared against experimental data. In addition, standard features of jets such as self-similarity, spreading ratios, and centerline velocity decay were verified from the solutions. Once the computations were validated, simulations were completed for each of the four cases at the six-foot recommended social distancing to determine the droplet concentration reduction. The simulations were run at increasing grid resolution to verify grid and time-step independence. Finally, the simulations were repeated for the case with face masks to assess the additional reduction of droplets reaching the receiver at the recommended distance. At the recommended social distancing with masking, the number of droplets coming into contact with others was reduced to negligible amounts. The simulations showed the recommended protocols are highly effective at reducing the transmission of COVID-19. © 2022, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

6.
ASHRAE Transactions ; 127:246-253, 2021.
Article in English | ProQuest Central | ID: covidwho-1980710

ABSTRACT

The purpose of a ventilation system for indoor spaces is to create a safe environment for the occupants by diluting the concentration levels of hazardous contaminants and to minimize the risk of infection due to spread of airborne pathogens. The effectiveness of ventilation system depends on several inter related factors including the supply airflow rate, number and locations of supply diffusers, and number and locations of return grilles. With the help of Computational Fluid Dynamics (CFD) analyses, this study systematically evaluates the impact of three different HVAC configurations on the airflow patterns, distribution of contaminant, and the risk of infection in a small office space with two cubicles. The HVAC configuration with a single supply and a single return can create adverse airflow patterns which can promote spread of contaminants and increase the risk of infection farther from the source. When an additional supply diffuser is introduced with the same single return, the zone of high risk of infection remained in the vicinity of the source. However, the overall risk of infection in the space remained the same. Addition of another return created aerodynamic containment zones in the space which provided easy path for the contaminated air to leave the space and reduced the overall risk of infection. Since the location of an infected individual is not known a priori, the aerodynamic containment with distributed supply and distributed return can be the best strategy for reducing the probability of infection in indoor spaces. These studies demonstrate that CFD analyses can help in identifying the potential risk of high infection due to poor airflow distribution into a space and can provide valuable insights for developing appropriate mitigation strategies to create safe indoor environment.

7.
Energies ; 15(14):11, 2022.
Article in English | Web of Science | ID: covidwho-1979187

ABSTRACT

Aerosol pollutant particles indoors significantly affect public health. The conventional wisdom is that natural ventilation will alleviate the dispersion of airborne or aerosol particles. However, we show that the problem is far more complex and that natural ventilation should be applied under specific conditions to be effective. We performed several simulations of a simplified (and easily reproducible) room with a window opening and aerosol particles stratified layers. Opening a window can scatter particles present in stratified layers indoors and potentially contribute to the degradation of indoor air quality for a significant period of time. Moreover, we show that thermal instabilities arising from the temperature gradients due to temperature differences between the indoor and outdoor environment spread the particles randomly indoors, adversely affecting air quality and architectural design. Recommendations for more efficient natural ventilation minimizing aerosol pollutant particles dispersed indoors are provided.

8.
ASHRAE Transactions ; 128:340-347, 2022.
Article in English | ProQuest Central | ID: covidwho-1970581

ABSTRACT

The wavelength band of200-280 nm of UV-C radiation generated by the Ultraviolet Germicidal Irradiation (UVGI) system can destroy the reproduction ability of microorganisms. Severalfactors related to UVfixtures, HVAC layout, and the resulting airflow flow patterns can affect the performance of upper-room UVGI applications. With the help of Computational Fluid Dynamics (CFD) analyses, this study systematically evaluates the impact of UV-C intensities on the effectiveness of an upper room UVGI system. It shows that the addition of even a small amount of UV-C energy in the upper region of space can significantly reduce the probability of infection as predicted by the Wells-Riley model. Increasing the UV-C output shows a further reduction in the infection probability, although with a diminishing impact. A further investigation is necessary to evaluate the effect of airflow patterns on the performance of UVGI systems. These studies demonstrate that CFD analyses can help optimize the performance of UVGI systems to minimize the probability of infection in indoor spaces.

9.
22nd Annual International Conference on Computational Science, ICCS 2022 ; 13353 LNCS:356-369, 2022.
Article in English | Scopus | ID: covidwho-1958889

ABSTRACT

In this study, we conducted a computational fluid dynamics analysis to estimate the trajectory of the virus-laden droplets. As numerical models, two human body models with airways were prepared. These models are represented by unstructured grids. Having calculated the unsteady airflow in the room, we simulated the trajectory of droplets emitted by the human speaking. In addition, inhaling the droplets into the lung of the conversation partner was simulated. The number of the droplets adhered to the respiratory lining of the partner was counted separately on the nasal cavity, oral cavity, trachea, bronchi, and bronchial inlet surface. The diameters of the droplets were also investigated in the same manner. It was noticeable that more than 80% of the droplets inhaled by the conversation partner adhered to the bronchial inlet surface. Also, the conversation partner did not inhale droplets larger than 35 μm in diameter. It was found that when the distance between two people was 0.75 m, more droplets adhered to the partner’s torso. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

10.
Journal of Aerosol Science ; 166:106051, 2022.
Article in English | ScienceDirect | ID: covidwho-1956188

ABSTRACT

Early in the CoViD-19 pandemic, musical practices, especially singing and playing wind instruments, have been pointed out as having a high risk disease transmission due to aerosol production. However, characterization of these emission sources was not consolidated. This study focuses on the generation of aerosols and potential reduction in the context of playing wind instruments and singing. Aerosol concentration reduction means are evaluated using aerosol measurements in clean room and Computational Fluid Dynamics. Measurements at the bell of a clarinet and in front of singers are performed with or without a protection (bell cover for clarinet and surgical mask for singers). Numerical results on clarinet suggest that most of the supermicron (≥1μm) particles are trapped on the walls of the instruments, which act as a filter, depending on toneholes configurations (closed or opened) changing the frequency of sound produced. Experimental results are consistent since almost only submicron particles contribute to the measured number concentration during playing clarinet. First of all, the high inter and intra-individuals variability is highlighted, with high coefficients of variation. This study highlights the impact of fingerings on the generated particles and the efficiency of protections such as bell cover (from 3 to 100 times), depending on the played note and players. Results for singers show that surgical masks significantly reduce the aerosol concentration (from 8 to 170 times) in front of the mouth. The evolution of aerosol concentration is also correlated with sound intensity.

11.
Energy Reports ; 2022.
Article in English | ScienceDirect | ID: covidwho-1956129

ABSTRACT

Many issues have emerged more clearly than before in multi-storey residential buildings during quarantine and lockdown caused by the global pandemic COVID-19. Among these problems is the deterioration in people’s mental and physical health inside the home caused by quarantine and closure. This deterioration is due to inadequate passive ventilation, natural lighting, and the lack of green open spaces in and around traditional multi-storey residential buildings. Also, one of the most severe problems is the airborne infection transmission from a positive covid-19 person to others due to the lack of control in the entrance of buildings against an infected person. In this paper, we modified the shape of a traditional multi-storey residential building. Using Design-Builder and Autodesk CFD software, we create a simulation to compare the amount of natural ventilation and lighting before and after modifying the building’s shape. This work aims to increase the passive ventilation and daylight inside the building. Also, to achieve the biophilic concept to provide open spaces for each apartment to improve the mental and physical health of the residents. In addition, it protects the building users from infection with the virus. Through this study, we found that passive ventilation and daylight achieved more efficiency in the building that we have modified in its shape, which led to a 38% reduction in energy consumption. In summary, these findings suggest that by modifying the mass of the traditional multi-storey residential building with open green spaces provided for each apartment, the natural connection with the inhabitants of the building was sufficiently provided. Moreover, all this will significantly help improve residents’ mental and physical state, and it will also help prevent the spread of various diseases inside the homes.

12.
Atmos Pollut Res ; 13(7): 101473, 2022 Jul.
Article in English | MEDLINE | ID: covidwho-1944213

ABSTRACT

The spread of respiratory diseases via aerosol particles in indoor settings is of significant concern. The SARS-CoV-2 virus has been found to spread widely in confined enclosures like hotels, hospitals, cruise ships, prisons, and churches. Particles exhaled from a person indoors can remain suspended long enough for increasing the opportunity for particles to spread spatially. Careful consideration of the ventilation system is essential to minimise the spread of particles containing infectious pathogens. Previous studies have shown that indoor airflow induced by opened windows would minimise the spread of particles. However, how outdoor airflow through an open window influences the indoor airflow has not been considered. The aim of this study is to provide a clear understanding of the indoor particle spread across multiple rooms, in a situation similar to what is found in quarantine hotels and cruise ships, using a combination of HVAC (Heating, Ventilation and Air-Conditioning) ventilation and an opening window. Using a previously validated mathematical model, we used 3D CFD (computational fluid dynamics) simulations to investigate to what extent different indoor airflow scenarios contribute to the transport of a single injection of particles ( 1 . 3 µ m ) in a basic 3D multi-room indoor environment. Although this study is limited to short times, we demonstrate that in certain conditions approximately 80% of the particles move from one room to the corridor and over 60% move to the nearby room within 5 to 15 s. Our results provide additional information to help identifying relevant recommendations to limit particles from spreading in enclosures.

13.
International Journal of Numerical Methods for Heat & Fluid Flow ; 32(9):2964-2981, 2022.
Article in English | ProQuest Central | ID: covidwho-1948670

ABSTRACT

Purpose>The purpose of this paper is to devise a tool based on computational fluid dynamics (CFD) and machine learning (ML), for the assessment of potential airborne microbial transmission in enclosed spaces. A gated recurrent units neural network (GRU-NN) is presented to learn and predict the behaviour of droplets expelled through breaths via particle tracking data sets.Design/methodology/approach>A computational methodology is used for investigating how infectious particles that originated in one location are transported by air and spread throughout a room. High-fidelity prediction of indoor airflow is obtained by means of an in-house parallel CFD solver, which uses a one equation Spalart–Allmaras turbulence model. Several flow scenarios are considered by varying different ventilation conditions and source locations. The CFD model is used for computing the trajectories of the particles emitted by human breath. The numerical results are used for the ML training.Findings>In this work, it is shown that the developed ML model, based on the GRU-NN, can accurately predict the airborne particle movement across an indoor environment for different vent operation conditions and source locations. The numerical results in this paper prove that the presented methodology is able to provide accurate predictions of the time evolution of particle distribution at different locations of the enclosed space.Originality/value>This study paves the way for the development of efficient and reliable tools for predicting virus airborne movement under different ventilation conditions and different human positions within an indoor environment, potentially leading to the new design. A parametric study is carried out to evaluate the impact of system settings on time variation particles emitted by human breath within the space considered.

14.
AIP Advances ; 12(7), 2022.
Article in English | Scopus | ID: covidwho-1947749

ABSTRACT

The present paper investigates droplet and aerosol emission from the human respiratory function by numerical and experimental methods, which is analyzed at the worst-case scenario, a violent sneeze without a face covering. The research findings develop the understanding of airborne disease transmission relevant to COVID-19, its recent variants, and other airborne pathogens. A human sneeze is studied using a multiphase Computational Fluid Dynamics (CFD) model using detached eddy simulation coupled to the emission of droplets that break up, evaporate, and disperse. The model provides one of the first experimental benchmarks of CFD predictions of a human sneeze event. The experiments optically capture aerosols and droplets and are processed to provide spatiotemporal data to validate the CFD model. Under the context of large random uncertainty, the studies indicate the reasonable correlation of CFD prediction with experimental measurements using velocity profiles and exposure levels, indicating that the model captures the salient details relevant to pathogen dispersion. Second, the CFD model was extended to study the effect of relative humidity with respect to the Wells curve, providing additional insight into the complexities of evaporation and sedimentation characteristics in the context of turbulent and elevated humidity conditions associated with the sneeze. The CFD results indicated correlation with the Wells curve with additional insight into features, leading to non-conservative aspects associated with increased suspension time. These factors are found to be associated with the combination of evaporation and fluid-structure-induced suspension. This effect is studied for various ambient air humidity levels and peaks for lower humidity levels, indicating that the Wells curve may need a buffer in dry climates. Specifically, we find that the increased risk in dry climates may be up to 50% higher than would be predicted using the underlying assumptions in Wells' model. © 2022 Author(s).

15.
Environ Technol Innov ; 28: 102837, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-1936411

ABSTRACT

The threat of epidemic outbreaks like SARS-CoV-2 is growing owing to the exponential growth of the global population and the continual increase in human mobility. Personal protection against viral infections was enforced using ambient air filters, face masks, and other respiratory protective equipment. Available facemasks feature considerable variation in efficacy, materials usage and characteristic properties. Despite their widespread use and importance, face masks pose major potential threats due to the uncontrolled manufacture and disposal techniques. Improper solid waste management enables viral propagation and increases the volume of associated biomedical waste at an alarming rate. Polymers used in single-use face masks include a spectrum of chemical constituents: plasticisers and flame retardants leading to health-related issues over time. Despite ample research in this field, the efficacy of personal protective equipment and its impact post-disposal is yet to be explored satisfactorily. The following review assimilates information on the different forms of personal protective equipment currently in use. Proper waste management techniques pertaining to such special wastes have also been discussed. The study features a holistic overview of innovations made in face masks and their corresponding impact on human health and environment. Strategies with SDG3 and SDG12, outlining safe and proper disposal of solid waste, have also been discussed. Furthermore, employing the CFD paradigm, a 3D model of a face mask was created based on fluid flow during breathing techniques. Lastly, the review concludes with possible future advancements and promising research avenues in personal protective equipment.

16.
Pharmaceutical Technology ; 45(11):34-40, 2021.
Article in English | EMBASE | ID: covidwho-1935337
17.
IEEE Conference on Virtual Reality and 3D User Interfaces (IEEE VR) ; : 855-856, 2022.
Article in English | Web of Science | ID: covidwho-1927532

ABSTRACT

One key factor in stopping the spread of COVID-19 is practicing social distancing. Visualizing possible sneeze droplets' transmission routes in front of an infected person might be an effective way to help people understand the importance of social distancing. This paper presents a mobile virtual reality (VR) interface that helps people visualize droplet dispersion from the target person's view. We implemented a VR application to visualize and interact with the sneeze simulation data immersively. Our application provides an easy way to communicate the correlation between social distance and infected droplets exposure, which is difficult to achieve in the real world.

18.
Sustainable Cities and Society ; : 104048, 2022.
Article in English | ScienceDirect | ID: covidwho-1926896

ABSTRACT

Previous studies show that upper-room ultraviolet germicidal irradiation (UVGI) systems can help contain infectious airborne viruses indoors. However, there has been a lack of research on the performance of an upper-room UVGI system in learning environments such as a school classroom. Since classrooms are more vulnerable to airborne transmission of diseases due to high occupancy for long hours, airborne infection characteristics are different from other occupied indoor environments (e.g., offices and residences). The objective of this study is to investigate UVGI system performance in a classroom considering detailed effects of ventilation rate, UV fluence rate, and UV radiating volume. Two analytical models, a one-zone and a two-zone material balance model, along with computational fluid dynamics (CFD) simulations, were employed to analyze viral aerosol concentrations under a representative range of classroom operating conditions. The CFD results show that increasing ventilation rate from 1.1 h–1 to 5 h–1 yields about 85% of airborne disinfection while doubling UV radiating volume results in a 60% disinfection. However, increasing UV fluence rate from 25 μW∙cm–2 to 50 μW∙cm–2 yields a moderate additional disinfection of 18%. Overall, the study results reveal that operating a UVGI system in an occupied classroom can markedly disinfect airborne viruses up to 96%, which is as effective as increasing ventilation rate more than five times. Furthermore, the results suggest that the one-zone and two-zone analytical models used in several previous studies could result in notably meaningful errors in analyzing viral aerosol concentrations, especially in occupied rooms with a highly non-uniform airflow distribution.

19.
Building Simulation ; : 14, 2022.
Article in English | Web of Science | ID: covidwho-1926088

ABSTRACT

Numerous short-term exposure events in public spaces were reported during the COVID-19 pandemic, especially during the spread of Delta and Omicron. However, the currently used exposure risk assessment models and mitigation measures are mostly based on the assumption of steady-state and complete-mixing conditions. The present study investigates the dynamics of airborne transmission in short-term events when a steady state is not reached before the end of the events. Large-eddy simulation (LES) is performed to predict the airborne transmission in short-term events, and three representative physical distances between two occupants are examined. Both time-averaged and phase-averaged exposure indices are used to evaluate the exposure risk. The results present that the exposure index in the short-term events constantly varies over time, especially within the first 1/ACH (air changes per hour) hour of exposure between occupants in close proximity, posing high uncertainty to the spatial and temporal evolutions of the risk of cross-infection. The decoupling analysis of the direct and indirect airborne transmission routes indicates that the direct airborne transmission is the predominated route in short-term events. It suggests also that the general dilution ventilation has a relatively limited efficiency in mitigating the risk of direct airborne transmission, but determines largely the occurrence time of the indirect one. Given the randomness, discreteness, localization, and high-risk characteristics of direct airborne transmission, a localized method that has a direct interference on the respiratory flows would be better than dilution ventilation for short-term events, in terms of both efficiency and cost.

20.
27th International Conference on Parallel and Distributed Computing, Euro-Par 2021 ; 13098 LNCS:255-266, 2022.
Article in English | Scopus | ID: covidwho-1919678

ABSTRACT

This work has started from the necessity of improving the accuracy of numerical simulations of COVID-19 transmission. Coughing is one of the most effective ways to transmit SARS-CoV-2, the strain of coronavirus that causes COVID-19. Cough is a spontaneous reflex that helps to protect the lungs and airways from unwanted irritants and pathogens and it involves droplet expulsion at speeds close to 50 miles/h. Unfortunately, it’s also one of the most efficient ways to spread diseases, especially respiratory viruses that need host cells in which to reproduce. Computational Fluid Dynamics (CFD) are a powerful way to simulate droplets expelled by mouth and nose when people are coughing and/or sneezing. As with all numerical models, the models for coughing and sneezing introduce uncertainty through the selection of scales and parameters. Considering these uncertainties is essential for the acceptance of any numerical simulation. Numerical forecasting models often use Data Assimilation (DA) methods for uncertainty quantification in the medium to long-term analysis. DA is the approximation of the true state of some physical system at a given time by combining time-distributed observations with a dynamic model in an optimal way. DA incorporates observational data into a prediction model to improve numerically forecast results. In this paper, we develop a Variational Data Assimilation model to assimilate direct observation of the physical mechanisms of droplet formation at the exit of the mouth during coughing. Specifically, we use high-speed imaging, from prior research work, which directly examines the fluid fragmentation at the exit of the mouths of healthy subjects in a sneezing condition. We show the impact of the proposed approach in terms of accuracy with respect to CFD simulations. © 2022, Springer Nature Switzerland AG.

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