Modeling transient particle transport in transient indoor airflow by fast fluid dynamics with the Markov chain method

Liu, Wei; Hooff, T. van; An, Yuting; Hu, Simon; Chen, Chun

doi:10.1016/j.buildenv.2020.107323

Cited by 24 publications

(8 citation statements)

References 42 publications

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“…Due to the lack of experimental data on the fluid dynamics of COVID-19 infected droplets, reviewing the available simulations on spreading the droplet through sneezing/coughing are helpful for a better understanding of modeling the COVID-19 transmission. Laminar, transient, and turbulent indoor airflow significantly affect the dispersion and transport of suspended droplets ( Liu et al, 2020 , Liu et al, 2020 , Liu and Chen, 2018 ). Furthermore, the indoor airflow becomes transient due to human behaviors involving walking, coughing, or sneezing.…”

Section: Introductionmentioning

confidence: 99%

“…They found that the direction of the cough and the area of mouth opening during coughing was not related to physiological parameters such as height, weight, and gender. The effects of human expiratory flows on respiratory infection in ventilated environments are investigated by Liu et al, 2020 , Liu et al, 2020 to minimize the infection risk of breathing. Their results indicated the large droplets deposit within a short distance and are hardly affected by the thermal stratification; however, droplet infection to the susceptible people could happen at close contact with the infector.…”

Section: Introductionmentioning

confidence: 99%

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COVID-19 spread in a classroom equipped with partition – A CFD approach

Mirzaie

Lakzian

Khan

et al. 2021

Journal of Hazardous Materials

134

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In this study, the motion and distribution of droplets containing coronaviruses emitted by coughing of an infected person in front of a classroom (e.g., a teacher) were investigated using CFD. A 3D turbulence model was used to simulate the airflow in the classroom, and a Lagrangian particle trajectory analysis method was used to track the droplets. The numerical model was validated and was used to study the effects of ventilation airflow speeds of 3, 5, and 7 m/s on the dispersion of droplets of different sizes. In particular, the effect of installing transparent barriers in front of the seats on reducing the average droplet concentration was examined. The results showed that using the seat partitions for individuals can prevent the infection to a certain extent. An increase in the ventilation air velocity increased the droplets’ velocities in the airflow direction, simultaneously reducing the trapping time of the droplets by solid barriers. As expected, in the absence of partitions, the closest seats to the infected person had the highest average droplet concentration (3.80 × 10 −8 kg/m 3 for the case of 3 m/s).

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

COVID-19 spread in a classroom equipped with partition – A CFD approach

Mirzaie

Lakzian

Khan

et al. 2021

Journal of Hazardous Materials

134

View full text Add to dashboard Cite

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“…Their results can provide high quality data for validating CFD models. In recent study, Liu et al [ 26 ]developed fast fluid dynamics with the Markov chain method to model the transient particle transport in transient indoor airflow. With this new method, the computational time was 7.8 times less than that of the CFD + Eulerian method.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Three Ventilation Strategies in a prefabricated COVID-19 inpatient ward

Ren

Wang

Liu

et al. 2021

Building and Environment

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Prefabricated inpatient wards have been proven to be an efficient alternative to quickly extend the caring capacity for patients. In this study, three typical ventilation strategies were studied using computational fluid dynamics in a prefabricated Coronavirus disease 2019 double-patient ward. Pollutants are the respiratory droplets and aerosols injected from two manikins. They are modelled as particles with different diameters (3 μm, 6 μm, 12 μm, 20 μm, 45 μm and 175 μm) by the Eulerian–Lagrangian model. Three ventilation strategies with an identical air change rate of 12.3 h −1 but different layouts of inlets and outlets are implemented. The flow field, flow structures and particle trajectories have been analysed and compared among the three ventilation strategies. The fate of particles is analysed and compared quantitatively. It is found that small particles (<20 μm) can move along with the main flow streams. Most of them are removed by ventilation to the outlet(s). Large particles (>45 μm) cannot move with the flow streams over a long path. Most of them deposit on solid surfaces in different regions of the ward in each ventilation strategy. Health workers should pay close attention to these polluted areas. Targeted cleaning of the polluted areas is necessary in a prefabricated inpatient ward. To promote the removal of some large particles (e.g., 45 μm) by the outlet(s), the outlet(s) should be installed inside the landing area of large particles and close to the polluted source(s).

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“…Abuhegazy et al provided a CFD simulation of a classroom in FLUENT and a detailed discussion on how windows, glass barriers as well as aerosol size and source might effect the particle trajectories [18]. Other CFD studies have considered the impact of ventilation on the distribution of aerosols from coughing using a commercial software [19] and particle trajectories in OpenFOAM [20] as well as utilizing far-UVC lightning as a virus inactivator [21]. Furthermore, various elements impacting the spread of airborne particles, such as ventilation, air filters and masks, have been considered in assorted CFD publications [22][23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

A GPU-accelerated computational fluid dynamics solver for assessing shear-driven indoor airflow and virus transmission by scale-resolved simulations

Korhonen¹,

Laitinen²,

Isitman³

et al. 2022

Preprint

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We explore the applicability of MATLAB for 3D computational fluid dynamics (CFD) of shear-driven indoor airflows. A new scale-resolving, large-eddy simulation (LES) solver titled DNSLABIB is proposed for MATLAB utilizing graphics processing units (GPUs). In DNSLABIB, the finite difference method is applied for the convection and diffusion terms while a Poisson equation solver based on the fast Fourier transform (FFT) is employed for the pressure. The immersed boundary method (IBM) for Cartesian grids is proposed to model solid walls and objects, doorways, and air ducts by binary masking of the solid/fluid domains. The solver is validated in two canonical reference cases. Then, we demonstrate the validity of DNSLABIB in a room geometry by comparing the results against another CFD software (OpenFOAM). Next, we demonstrate the solver performance in several isothermal indoor ventilation configurations and the implications of the results are discussed in the context of airborne transmission of COVID-19. The novel numerical findings using the new CFD solver are as follows. First, a linear scaling of DNSLABIB is demonstrated and a speed-up by a factor of 3-4 is also demonstrated in comparison to similar OpenFOAM simulations. Second, ventilation in three different indoor geometries are studied at both low (0.1m/s) and high (1m/s) airflow rates corresponding to Re = 5000 and Re = 50000. An analysis of the indoor CO 2 concentration is carried out as the room is emptied from stale, high CO 2 content air. We estimate the air changes per hour (ACH) values for three different room geometries and show that the numerical estimates from 3D CFD simulations may differ by 80-150 % (Re = 50000) and 75-140 % (Re = 5000) from the theoretical ACH value based on the perfect mixing assumption. Third, the analysis of the CO 2 probability distributions (PDFs) indicates a relatively non-uniform distribution of fresh air indoors. Fourth, utilizing a time-dependent Wells-Riley analysis, an example is provided on the growth of the cumulative infection risk which is shown to reduce rapidly after the ventilation is started. The average infection risk is shown to reduce by a factor of 2 for lower ventilation rates (ACH=3.4-6.3) and 10 for the the higher ventilation rates (ACH=37-64). Finally, we utilize the new solver to comment on respiratory particle transport indoors. The primary contribution of the paper is to provide an efficient, GPU compatible CFD solver environment enabling scale-resolved simulations (LES/DNS) of airflow in large indoor 1 geometries on a desktop computer. The demonstrated efficacy of MATLAB for GPU computing indicates a high potential of DNSLABIB for various future developments on airflow prediction.

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Modeling transient particle transport in transient indoor airflow by fast fluid dynamics with the Markov chain method

Cited by 24 publications

References 42 publications

COVID-19 spread in a classroom equipped with partition – A CFD approach

COVID-19 spread in a classroom equipped with partition – A CFD approach

Numerical Study of Three Ventilation Strategies in a prefabricated COVID-19 inpatient ward

A GPU-accelerated computational fluid dynamics solver for assessing shear-driven indoor airflow and virus transmission by scale-resolved simulations

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