Eur. Phys. J. Special Topics 222, 199-210 (2013)
https://doi.org/10.1140/epjst/e2013-01835-x

Regular Article

Numerical investigation of the effect of insoluble surfactant on drop formation in microfluidic device

¹ Department of Mechanical Engineering, Eindhoven University of Technology, 5600MB Eindhoven, The Netherlands
² Institute for Complex Molecular Systems, Eindhoven University of Technology, 5600MB Eindhoven, The Netherlands

^a e-mail: P.D.Anderson@tue.nl

Received: 16 April 2013
Revised: 23 April 2013
Published online: 17 June 2013

Abstract

Surfactants are commonly used in droplet-based microfluidics to stabilize the droplet interface. In this study, we investigate the effect of insoluble surfactant on drop formation in a capillary microfluidic device. We use a diffuse-interface method to describe the evolution of interface involving insoluble surfactant. The Navier-Stokes/Cahn-Hilliard equations and the surfactant conservation equation are solved by a finite element method along with a grid deformation method. As the surfactant has a non-uniform distribution during the drop formation in general, the surface tension has a gradient on the interface, which affects the flow field and interface evolution. The surfactant effect is discussed for dripping and jetting regimes.