# COVID-19, Simulation and Computational Fluid Dynamics

The 2020 Coronavirus (COVID-19) pandemic has affected everyone in the world, with ramifications in our public health, prosperity and beyond. There are so many lessons we can draw. I will focus on two: Science and Simulation on the one hand, and Community and Collaboration on the other. I will give you my perspective as a professional at a software company.

Let’s do a simple math about the scale of exponential growth and epidemics turning into pandemics: If a person with a contagious infection spreads the disease to just one other person every two days, then after only 10 days, 32 people will be infected, that is 2 to the power of 5. But if the rate of spread is one per day, you have 2 to the power of 10, that is 1024. Again, 32 vs. 1024! These ratios will be more drastic depending on the reproduction number, incubation period, overall length of the pandemic, the population and other factors, but you get the point about exponential growth.

This was simple math to do an Analysis. Why is Simulation important? Because knowing what may happen, in the case of the pandemic, saves lives and avoids economic collapse. In product development, we advocate for Simulation every day, using sophisticated software and methods such as Finite Element Analysis FEA and Computational Fluid Dynamics (CFD) to help designers, engineers and analysts come up with better products faster, cheaper and more efficiently, ultimately improving the quality of life.

In this pandemic, the U.S. Centers for Disease Control (CDC) is promoting “Social distancing.” The recommendation is to stay apart at least six feet, or two meters, to avoid passing infections. Why is it? COVID-19 is an infectious disease that spreads from person to person mainly from droplets when an infected person coughs or sneezes. So, the right distance is a function of the reach of the pathogen.

You can see this complicated phenomenon of sneeze experimentally, using slow motion footage from cameras with extremely high frames per second. Scientifically, sneeze is a very complicated phenomenon, with multi-phase turbulent clouds, gaseous phase coupled with droplets. A face mask can create the obstruction or re-direction between the person sneezing and the person exposed.

With some applications, HVAC design for a building for example, multiple physical tests are very expensive, time-consuming and simply not efficient. Even for a simple application like pressure drop and valve design or heat buildup in a computer box, virtual testing is very beneficial. CFD is extremely useful in these applications and beyond, for gas and liquid flow as well as thermal analysis. Such simulations are fast and cost-effective. Especially during the initial design and engineering phase, they enable the engineer to look at many “what-if” scenarios, improving efficiency and productivity, and thus, have the highest impact. As we see in this pandemic, prevention and early preparation are not only smarter but also cheaper than late mitigation.

Another lesson learned from COVID-19 is the aspect of community and collaboration. Unity in diversity, the world has inter-dependencies that cannot be suppressed or ignored. In our industry, for a product to succeed in the market, you need the collaboration of multiple stakeholders, from product development and design to engineering simulation, manufacturing, marketing, sales and others. Ideally, they would interact in an efficient collaborative interactive environment. Dassault Systemès 3DEXPERIENCE is a platform with this philosophy in mind.

Please check out our OPEN COVID-19 global and online community where we are leveraging collective intelligence to source, qualify, design, engineer and manufacture rapid solutions during this pandemic.

This pandemic has given us a new perspective: the value of life, our families and all our loved ones. We are in this together and everybody has a role to play. In my profession and the field of Simulation, the mission statement of the company I work for, makes more sense to me today than ever before: “Dassault Systèmes provides business & people with 3DEXPERIENCE universes to imagine sustainable innovations capable of harmonizing product, nature and life.

#### Dr. Reza Tabatabai

Reza Tabatabai is a Sr. Technical Manager for Simulation products, focusing on SOLIDWORKS Simulation and SIMULIA works product portfolios at Dassault Systèmes. He has 20 years of industry experience. Reza received his PhD from the Swiss Federal Institute of Technology (ETH Zurich) and was a Lecturer & Research Associate at the University of California at Berkeley.