Date of Graduation


Document Type


Degree Type



Statler College of Engineering and Mineral Resources


Mechanical and Aerospace Engineering

Committee Chair

Ismail B. Celik.


Cough, sometimes shedding plenty of germs and virus, is the human body's way of cleaning the breathing passages. The virus and germs spread rapidly through ambient air among humans and may cause infection. To reduce ultimately the infections caused by the germs and virus contained in human saliva droplets, it is necessary to understand the vaporization process of human saliva and its role on virus transmission. Virus-laden droplets, shed by an infected person through coughing and sneezing, evaporate until becoming droplet nuclei which will remain airborne for a long time and can infect other people. In other words, evaporation rate is an important factor affecting the transmission of virus and germ contained in human saliva. Accordingly, the present research focuses the evaporation of human saliva droplets, the carriers of virus. Experiments and numerical methods are utilized in this research to study surface tension and evaporation rate. In order to determine which component influences the surface tension and evaporation rate of droplet, different solutions are evaluated. Capillary tubes and a high performance camera are used for measuring the surface tension of these solutions. Evaporation measurements were carried out by taking pictures of droplets hanging vertically from a thin needle or laying on a flat surface. These images were later postprocessed using an in-house developed Matlab code to obtain the evaporation rate. A more general evaporation equation was derived to determine numerically the evaporation rate of the different solutions and then used to analyze the evaporation process of multi-component droplets. Eventually, the numerical results compare reasonably well with the experimental measurements. These findings will help understand the role of temperature and relative humidity of ambient air in virus transmission.