Using Computational Fluid Dynamics (CFD) analysis, engineers are uniquely positioned to analyze the transmission of droplet particles.”

Mehran Salehi, Senior CFD Analyst, Southland Industries


As the COVID-19 pandemic continues on, scientists, medical professionals, and even engineers have relied on their expertise to study and better understand the behavior of the virus. COVID-19 is primarily spread through person-to-person contact and droplets attached to airborne particles through the air.

As coronavirus infections are continuing to spread quickly and endanger many lives every day, an enormous strain on healthcare infrastructures and economical losses around the world increases. Since there is still no proven treatment or vaccine for this disease, the best procedure to prevent getting this virus is to avoid exposure. Therefore, social distancing has and continues to be an important way to fight this disease.

Using Computational Fluid Dynamics (CFD) Analysis, engineers are uniquely positioned to analyze the transmission of droplet particles. The analysis is extremely useful for simulating particle propagation and dispersion within various situations. Through this analysis, safe petameters can be set to avoid further spreading the disease. Additionally, customized conditions within hospital rooms such as specific layouts and air conditioning should also be taken into consideration.

Typically, CFD allows design engineers to analyze the flow field and temperature distribution within a designated area as well as the thermal and load stresses of corresponding facility structure. By parameterizing the design variables and performing sensitivity analysis, the design phase is shortened, effectively producing optimized design.

CFD Analysis of COVID-19 Spread

In this COVID-19 CFD Analysis Study, the model of two persons standing at six-foot distances from each other is simulated. It shows one person coughing with the speed of 50 m/s. The expelled cough droplets are modeled using a Discrete Particle Model (DPM). These droplets range between 1 and 100 microns in diameter. In this simulation, it is assumed that there is no air conditioning within the room to better capture the full behavior of the coughing flow. However, designing appropriate air conditioning can prevent particles from spreading within more areas by extracting them from the room through returns or isolating them at locations far from other people.

Backed with this knowledge and evolving healthcare practices, individuals can move forward with a better understanding of the COVID-19 behavior through droplet propagation.”

Mehran Salehi, Senior CFD Analyst, Southland Industries

But, now that engineering expertise has been used to show the simulation of COVID-19 particle propagation, what are the implications for individuals as this pandemic continues on? The results from this study confirm that most particles lose their axial momentum within a six-foot range with heavier particles starting to fall to the ground faster due to gravity compared to lighter ones which tend to stay airborne longer. Specifically, in this study, it is assumed that the persons are not wearing face masks or protection to prevent cough droplets from spreading.

Backed with this knowledge and evolving healthcare practices, individuals can move forward with a better understanding of the COVID-19 behavior through droplet propagation, protecting themselves and others.


  • Mehran Salehi, PhD

    CFD Analyst

    As a Computational Fluid Dynamics (CFD) Analyst at Southland Engineering, Mehran Salehi uses thermal and flow simulations to create efficient, optimal, and cost-effective designs for projects. Since joining the industry in 2016, Mehran has utilized his extensive knowledge to predict failure scenarios and reduce costs. He relies on his experience with CFD and fluid mechanics to optimize heating and cooling requirements within mission critical and healthcare facilities. He is also an associate member of the American Society of Heating, Refrigerating, and Air Conditioning Engineers.

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