Microfluidic Droplets

This work was predominantly funded by an Australian Research Council Linkage (CSIRO) grant, `Drop deformation in confined microfluidic geometries' (LC0348317).

A parametric study of droplet deformation through a microfluidic contraction-expansion

Dalton Harvie, Malcolm Davidson, Justin Cooper-White, Murray Rudman and Gary Rosengarten

Section under construction

Viscoelastic droplets

Dalton Harvie, Malcolm Davidson and Justin Cooper-White

We have also studied the behaviour of viscoelastic droplets that pass through microfluidic contraction-expansions. The particular simulation shown below is based on an experiment performed in a thin planar contraction, in which a small `packet' of surrounding continuous phase Newtonian fluid was encapsulated within the viscoelastic PEO droplet after it had passed through the 4:1:4 contraction (see the publication).

Above: Simulation of a viscoelastic droplet that is surrounded by a Newtonian fluid and passes through a planar contraction. The simulations are performed in 2D Cartesian coordinates and use an Oldroyd-B `dumbbell' model to capture polymer rheology. Numerically a coupled VOF method was used to simultaneously advect the fluid volume fractions and dumbbell orientation tensors (more details in numerical methods). The shading represents the nondimensional length of the polymers (the square root of the trace of the orientation tensor). The `vectors' indicate the average length and principal orientation of the polymers.

The 2D simulations (above) capture the formation of a precursory forked tail on the droplet while it is within the contraction. They also predict the formation of a stress field, created by the extension and orientation of the polymers, that supports the encapsulation of continuous phase fluid from the rear of the droplet forward, along its centreline. Substantial encapsulation of the surrounding fluid is not predicted by the simulations: This is most probably because of the 2D Cartesian approximation employed to make the problem computationally tractable.

Work is ongoing to simulate this physical process in cylindrical and Cartesian 3D coordinates.

Publications

2004
[18]Simulating the deformation of Newtonian and Non-Newtonian drops through a micro-fluidic contraction (; and ), In 15th Australasian Fluid Mechanics Conference, . [bibtex] [pdf]
2005
[17] Flow focusing in microchannels (; and ), In ANZIAM J. (CTAC2004) (May, Rob; Roberts, A. J., eds.), volume 46(E), . [bibtex] [url]
[16] Using Computational Fluid Dynamics to study the effect of contact angle on microdroplet deformation (; and ), In ANZIAM J. (CTAC2004) (May, Rob; Roberts, A. J., eds.), volume 46(E), . [bibtex] [url]
[15] A parametric study of droplet deformation through a microfluidic contraction (; ; and ), In ANZIAM J. (CTAC2004) (May, Rob; Roberts, A. J., eds.), volume 46(E), . [bibtex] [url]
2006
[14]Simulations of viscoelastic droplet deformation through a micro-fluidic contraction (; and ), In WIT Transactions on Engineering Science, volume 52, . [bibtex] [doi]
[13]A parametric study of droplet deformation through a microfluidic contraction: Low viscosity Newtonian droplets (; ; and ), In Chemical Engineering Science, volume 61, . [bibtex] [doi]
[12]Contact angle effects on microdroplet deformation using CFD (; and ), In Applied Mathematical Modelling, volume 30, . [bibtex] [doi]
[11]Simulations of pendant drop formation of a viscoelastic liquid (; and ), In Korea-Australia Rheology Journal, volume 18, . [bibtex]
2007
[10] Predicting the effect of interfacial flow of insoluble surfactant on the deformation of drops rising in a liquid ( and ), In ANZIAM J. (CTAC2006), volume 48, . [bibtex] [url]
[9]A parametric study of droplet deformation through a microfluidic contraction: Shear thinning liquids (; ; and ), In International Journal of Multiphase Flow, volume 33, . [bibtex] [doi]
[8]Droplet deformation through a microfluidic contraction with interfacial flow of insoluble surfactant ( and ), In 6th International Conference on Multiphase Flow (ICMF 2007), . [bibtex]
2008
[7]Deformation of a viscoelastic droplet passing through a microfluidic contraction (; and ), In Journal of Non-Newtonian Fluid Mechanics, volume 155, . [bibtex] [doi]
[6]Effect of surfactant on drop deformation through a microfluidic contraction: The encapsulation phenomenon ( and ), In HEAT 2008, Fifth International Conference on Transport Phenomena In Multiphase Systems, . [bibtex]
2010
[5] Viscoelastic drop deformation in a micro-contraction ( and ), In 7th International Conference on Multiphase Flow (ICMF), . [bibtex] [url]
2011
[4]Viscoelastic drop deformation in a micro-contraction ( and ), In Fluid Dynamics and Materials Processing, volume 7, . [bibtex]
[3] Comparative evaluation of microfluidic circuit model performance for electroviscous flow (; and ), In ANZIAM J. (CTAC2010) (McLean, W.; Roberts, A. J., eds.), volume 52, . [bibtex] [url]
2014
[2] Effect of surfactants on single bubble sonoluminescence behavior and bubble surface stability (; ; ; ; and ), In Physical Review E, volume 89, . [bibtex] [url] [doi]
2017
[1] Electrophoretically mediated partial coalescence of a charged microdrop (; ; and ), In Chemical Engineering Science, volume 169, . [bibtex] [url] [doi]