Effect of gravitational field on droplet generation in microfluidic device: A numerical study

Droplet-based microfluidic platforms get more attention every day due to their increasing usage in chemical and biological applications such as cell lysis and micromixing. The aim of this study is to investigate the effects of the gravitational field on a droplet generation microfluidic chip and the secondary flows inside a generated droplet. In this study, a numerical simulation of a flow-focusing device with a T-junction geometry is simulated through the finite element method. It is assumed that the fluid is incompressible and Newtonian while the fluid flow is laminar. The results show that the chip’s orientation significantly affects the droplet formation process since body force influence on the fluids with un-matched densities, differs. The less-dense fluid tends to move upward in the presence of gravity force. Furthermore, the gravitational field has a noticeably impact on the droplet’s secondary flow and causes unsymmetric vortices while making a non-uniform fluid flow in the central part of the droplet. The provided simulation results can be implied in further studies on microfluidic systems in variable gravitational environments such as space science applications.