Publications by Year: 2018

2018
Edery, Y. ; Berg, S. ; Weitz, D. Surfactant Variations in Porous Media Localize Capillary Instabilities during Haines Jumps. Physical Review Letters 2018, 120. Publisher's VersionAbstract
We use confocal microscopy to measure velocity and interfacial tension between a trapped wetting phase with a surfactant and a flowing, invading nonwetting phase in a porous medium. We relate interfacial tension variations at the fluid-fluid interface to surfactant concentration and show that these variations localize the destabilization of capillary forces and lead to rapid local invasion of the nonwetting fluid, resulting in a Haines jump. These spatial variations in surfactant concentration are caused by velocity variations at the fluid-fluid interfaces and lead to localization of the Haines jumps even in otherwise very uniform pore structure and pressure conditions. Our results provide new insight into the nature of Haines jumps, one of the most ubiquitous and important instabilities in flow in porous media.
Zhang, H. ; Zhu, Y. ; Qu, L. ; Wu, H. ; Kong, H. ; Yang, Z. ; Chen, D. ; Mäkilä, E. ; Salonen, J. ; Santos, H. A. ; et al. Gold nanorods conjugated porous silicon nanoparticles encapsulated in calcium alginate nano hydrogels using microemulsion templates. Nano Letters 2018, 18, 1448-1453. Publisher's Version hongbo_zhang_et_al_2018_nanoletters.pdf
Montessori, A. ; Lauricella, M. ; La Rocca, M. ; Succi, S. ; Stolovicki, E. ; Zibalt, R. ; Weitz, D. Regularized lattice Boltzmann multicomponent models for low capillary and Reynolds microfluidics flows. Computers & Fluids 2018, 167, 33-39. Publisher's VersionAbstract
We present a regularized version of the color gradient lattice Boltzmann (LB) scheme for the simulation of droplet formation in microfluidic devices of experimental relevance. The regularized version is shown to provide computationally efficient access to capillary number regimes relevant to droplet generation via microfluidic devices, such as flow-focusers and the more recent microfluidic step emulsifier devices.
Stolovicki, E. ; Ziblat, R. ; Weitz, D. A. Throughput enhancement of parallel step emulsifier devices by shear-free and efficient nozzle clearance. Lab on a Chip 2018, 132-138. Publisher's Version