Nav: Home

How nanoparticles affect flow through porous stuff in surprising ways

April 04, 2017

WASHINGTON, D.C., April 4, 2017 -- Those who have mixed oil and vinegar may have unknowingly observed a strange fluid phenomenon called fingering instability. A type of this phenomenon, called viscous fingering (VF), occurs in porous media where fluids of differing viscosity converge in finger-shaped patterns as a result of growing disturbances at the interface.

Such instabilities are encountered in a wide variety of fields. For applications like the oil recovery process, or contaminant transport in soil, where a fluid is injected to displace oil or contaminants, a uniform fluid front is required to achieve the highest volumetric sweep and effectiveness, making such instabilities undesirable.

On the other hand, in microfluidic devices such as micromixers where inertial effects are negligible, VF is an effective means of enhancing the mixing rate of the fluids. Understanding different aspects of this phenomenon, and the variables that can control things like instabilities and velocity distribution dynamics, can potentially offer options to control and utilize these effects more effectively.

A team of researchers at the University of Calgary has been working on this area for a long time and recently made great strides in understanding the phenomenon. They report their findings this week in the journal Physics of Fluids, from AIP Publishing.

"My work is part of the puzzle in the evolution in this research area," said Benham Dastvareh, a researcher at the University of Calgary. "My research allows me to combine my interest in mathematics, numerical methods and fundamental research in transport phenomena, and particularly fluid mechanics."

Employing a comprehensive approach, the Calgary researchers incorporated the nonlinear simulation of the growing fingers and also analytical stability analysis of nanofluid displacement in a porous media. By combining the advantages of these methods, they achieved better and more comprehensive understanding of the phenomenon.

Results revealed that nanoparticles cannot make an otherwise stable flow unstable, but they can enhance or attenuate the instability of an originally unstable flow. Increasing either the nanoparticles' deposition rate or their rate of diffusion destabilized the flow. Furthermore, nanoparticle deposition can change an initial monotonically decreasing viscosity distribution -- one that is purely decreasing or unchanging, to a non-monotonic one, and results in the development of vortex dipoles.

"Analyses of vortex structures along with the viscosity distributions allowed us to explain the observed trends and the resulting finger configurations, Dastvareh said. "This work opens a gate for further studies and represents new findings that can be used to control the growing instabilities in the presence of nanofluids for different applications."

This work may also have potential applications for drug delivery, where nanoparticles can't penetrate easily through a porous medium. "It is possible that viscous fingering could be used to open a channel in the human tissue to transfer these nanoparticles for clinical treatment," Dastvareh said.
The article, "Instabilities of nanofluid flow displacements in porous media," is authored by Behnam Dastvareh and Jalel Azaiez. The article will appear in the journal Physics of Fluids April 4, 2017 (DOI: 10.1063/1.4978890). After that date, it can be accessed at


Physics of Fluids is devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex or multiphase fluids. See

American Institute of Physics

Related Nanoparticles Articles:

Study models new method to accelerate nanoparticles
In a new study, researchers at the University of Illinois and the Missouri University of Science and Technology modeled a method to manipulate nanoparticles as an alternative mode of propulsion for tiny spacecraft that require very small levels of thrust.
Actively swimming gold nanoparticles
Bacteria can actively move towards a nutrient source -- a phenomenon known as chemotaxis -- and they can move collectively in a process known as swarming.
Nanoparticles take a fantastic, magnetic voyage
MIT engineers have designed tiny robots that can help drug-delivery nanoparticles push their way out of the bloodstream and into a tumor or another disease site.
Quantum optical cooling of nanoparticles
One important requirement to see quantum effects is to remove all thermal energy from the particle motion, i.e. to cool it as close as possible to absolute zero temperature.
Nanoparticles help realize 'spintronic' devices
For the first time researchers have demonstrated a new way to perform functions essential to future computation three orders of magnitude faster than current commercial devices.
More Nanoparticles News and Nanoparticles Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...