Effect of droplet deformation and internal circulation on drag coefficient

In the study of sprays, a theoretical gap exists between droplet modeling and reality, especially in high pressure applications like jet engine combustion. In this paper, we use interface-capturing direct numerical simulations of freely deforming droplets to demonstrate the impact of droplet deformation and liquid internal circulation on drag. An increase of over 200% in drag can be seen, depending on the conditions studied. We further showed that these phenomena can be quantified by the pressure and the Weber number, and a correlation for droplet drag was obtained based on these factors.