Coronavirus Dispersion in an Elevator due to Sneeze

Coronavirus Dispersion in an Elevator Cabin Due to a Sneeze, CFD Simulation by ANSYS Fluent

The coronavirus (COVID-19) is currently recognized as the greatest human challenge in the world; Because this disease, in addition to being dangerous to human health, has a high transmission power between sick people and healthy people.

Coughing or sneezing of a sick person without a mask in space causes the spread of coronaviruses. One of the important recommendations of physicians in preventing the transmission of disease between people is to care about the social distance between people in society.

The elevator cabin is one of the most important spaces in the discussion of coronavirus disease; Because usually a number of people with the shortest possible distance are placed in a small space with a not very strong ventilation system.

In this project, based on the CFD method and using ANSYS Fluent software, an attempt has been made to simulate the coronavirus particles dispersion from the carrier patient cough inside an elevator cabin.

This model includes a computational domain in the form of an elevator cabin in which two humans are modeled; One of them is considered a coronavirus patient who coughs or sneezes and the other person is considered a person who is at a certain distance from the patient and is exposed to the coronavirus particles.

The purpose of this work is to investigate the ability of virus particles to spread inside the elevator interior and the possibility of transmitting it to another person.

According to this definition of injection, human cough virus particles are physically expelled from the patient’s mouth by water droplets that are evaporating in space.

These virus droplets have a temperature of 310 K, a velocity of 31.85 m/s, and a mass flow of 0.018 kg/s, which are emitted at intervals of 0s to 0.1s.

The particle diameter of the virus is not constant during propagation and the rosin-rammler-logamethric distribution method is considered for the size of the diameters.

The present model is designed in three dimensions using SOLIDWORKS and Design Modeler software.  Also, we carried out the meshing of the model using ANSYS Meshing software and the mesh type is unstructured. The element number is 454433.

CFD Methodology

For the present simulation, the discrete phase model (DPM) is used; Because this model allows us to study a mass of particles discretely in a continuous fluid space.

Due to the choice of this model, the wet particles of the coronavirus secreted from the patient’s mouth are considered a discrete phase and the airflow transmitted through the elevator ventilation valves is considered a continuous phase inside the interior of the elevator cabin.

The physical models of discrete particles defined in this simulation include two-way turbulence coupling meaning the two-way interaction between continuous and discrete phase (in addition to the discrete phase being affected by the continuous phase, by activating the interaction with continuous phase mode, the discrete phase also affects the continuous phase), stochastic collision means irregular droplets collide with each other, coalescence means droplets merge with each other, and breakup means The collapse of the droplets.

Following this method and the relevant formulation, the values related to the minimum, maximum and average diameter size determine the exponential parameter of the spread and the number of diameters per injection.

It should be noted that the drop mode is applied when the species transport model is also activated. In addition, the energy equation is activated to consider the temperature changes.

Coronavirus Dispersion in an Elevator Conclusion

At the end of the solution process, we obtain the virus particle tracking at the last second of the simulation process. This particle tracking is based on residence time and particle diameter size.

We also export the animation of the virus dispersion and its disappearance over time and attached it to the project report file. Finally, we obtain three-dimensional contours related to the temperature and mass fraction of oxygen released from the ventilation system and water droplets secreted from the cough.