Person

Mathias Nagel

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Related publications (9)

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Boundary elements method for microfluidic two-phase flows in shallow channels

François Gallaire, Mathias Nagel

In the following work we apply the boundary element method to two-phase flows in shallow microchannels, where one phase is dispersed and does not wet the channel walls. These kinds of flows are often encountered in microfluidic Lab-On-A-Chip devices and ch ...

Elsevier2015

A numerical study of droplet trapping in microfluidic devices

François Gallaire, Pierre-Thomas Paul Brun, Mathias Nagel

Microfluidic channels are powerful means of control of minute volumes such as droplets. These droplets are usually conveyed at will in an externally imposed flow which follows the geometry of the micro-channel. It has recently been pointed out by Dangla et ...

Amer Inst Physics2014

We reconsider the radial Saffman-Taylor instability when a fluid injected from a point source displaces another fluid of higher viscosity in a Hele-Shaw cell where the fluids are confined between two neighboring flat plates. The advancing fluid front is un ...

2013

Deformable Droplets, a numerical account

François Gallaire, Mathias Nagel

We simulate confined droplets in microchannels by depth-averaged equations solved by a boundary element method. The retarding effect due to film formation is absent in the depth-averaged approach and added by a nonlinear boundary condition. Although deform ...

2013

Investigation of droplet shedding in flow focusing geometries using the boundary element method.

François Gallaire, Mathias Nagel

Shedding of droplets in a flow focusing junction is standard technique in two-phase microfluidics. This break-up is driven by a capillary instability. Here we present a depth-averaged approach to simulate these complex phenomena. Since the physical mechani ...

2013

Generic path for droplet relaxation in microfluidic channels

François Gallaire, Pierre-Thomas Paul Brun, Mathias Nagel

In two-phase microfluidics, droplets often undergo deformations that drive them away from their circular equilibrium shape. Herein we concentrate on the relaxation of symmetrical deformations to a circle driven by surface tension effects, which are predomi ...

American Physical Society2013

Studying Droplet dynamics by depth-averaged simulation

François Gallaire, Mathias Nagel

Droplets in flat micro channels are deformable, avoid obstacles, interact with one another and undergo separation and coealescence. For the simulation of these micro fluidic two-phase flows we propose a depth-averaged model derived from the Stokes equation ...

2012

Numerical pancake droplets: from capturing to versatile microfluidics

François Gallaire, Mathias Nagel

This article proposes a numerical model for microfluidic two-phase flows in flat channels, also called Hele-Shaw cells. The initially three-dimensional problem is simplified to two-dimensions by depth averaging in the thin direction. The 2D partial differe ...

SOCIETE HYDROTECHNIQUE DE FRANCE2012

Existing linear stability analysis of radial fingering in Hele-Shaw cells use Darcy’s law as a model for the fluid motion. Comparison between experiments and theory reveals a large discrepancy at order 1 capillary numbers. In this work we use the so-called ...

Association Française De Mécanique2011