Soft Matter and Complex Systems Seminar
Sala Seminaryjna Teoretyczna, ul. Hoża 69
2014-02-28 (09:30) 
Agnieszka Budek (IFT UW)
Viscous fingering patterns in rectangular grid geometry
I study experimentally and numerically two-phase flow in a rectangularnetwork of microfluidic channels. If the pressure gradient is orientedalong the lattice, growth of long and thin dendrites (’thin fingers’)is promoted.The dynamics of thin finger growth is of interest due to theirappearance in a variety of other pattern forming systems, such as thegrowth of dendrites in electrochemical deposition experiments,channeling in dissolving rocks or side-branches growth in crystallization. Due to their simplicity, thin finger models are also attractive for theoreticalanalysis.
A characteristic feature of these systems is a strong competitionbetween the fingers which is a reflection of Saffman-Taylor instabilityacting in a nonlinear regime. Surprisingly, the case of miscible fluidsturns out to be different, with the competition between the fingers hindered due to the strong lateral currents of the displaced fluid, which eventuallycut off the heads of the advancing fingers, thus preventing theirfurther growth. The heads continue to move through the system, preserving their shapes, thus forming the ’miscible droplets’. In immisciblecase this process is hindered by the presence of the surface tension.A detailed analysis of this phenomenon is given with a particular emphasis on the scaling properties of the system.
A characteristic feature of these systems is a strong competitionbetween the fingers which is a reflection of Saffman-Taylor instabilityacting in a nonlinear regime. Surprisingly, the case of miscible fluidsturns out to be different, with the competition between the fingers hindered due to the strong lateral currents of the displaced fluid, which eventuallycut off the heads of the advancing fingers, thus preventing theirfurther growth. The heads continue to move through the system, preserving their shapes, thus forming the ’miscible droplets’. In immisciblecase this process is hindered by the presence of the surface tension.A detailed analysis of this phenomenon is given with a particular emphasis on the scaling properties of the system.
I study experimentally and numerically two-phase flow in a rectangularnetwork of microfluidic channels. If the pressure gradient is orientedalong the lattice, growth of long and thin dendrites (’thin fingers’)is promoted.The dynamics of thin finger growth is of interest due to theirappearance in a variety of other pattern forming systems, such as thegrowth of dendrites in electrochemical deposition experiments,channeling in dissolving rocks or side-branches growth in crystallization. Due to their simplicity, thin finger models are also attractive for theoreticalanalysis.
A characteristic feature of these systems is a strong competitionbetween the fingers which is a reflection of Saffman-Taylor instabilityacting in a nonlinear regime. Surprisingly, the case of miscible fluidsturns out to be different, with the competition between the fingers hindered due to the strong lateral currents of the displaced fluid, which eventuallycut off the heads of the advancing fingers, thus preventing theirfurther growth. The heads continue to move through the system, preserving their shapes, thus forming the ’miscible droplets’. In immisciblecase this process is hindered by the presence of the surface tension.A detailed analysis of this phenomenon is given with a particular emphasis on the scaling properties of the system.
A characteristic feature of these systems is a strong competitionbetween the fingers which is a reflection of Saffman-Taylor instabilityacting in a nonlinear regime. Surprisingly, the case of miscible fluidsturns out to be different, with the competition between the fingers hindered due to the strong lateral currents of the displaced fluid, which eventuallycut off the heads of the advancing fingers, thus preventing theirfurther growth. The heads continue to move through the system, preserving their shapes, thus forming the ’miscible droplets’. In immisciblecase this process is hindered by the presence of the surface tension.A detailed analysis of this phenomenon is given with a particular emphasis on the scaling properties of the system.