Gallery of Complex Flow

Labyrinth of gold


Labyrinth formed by fingers of air invading a mixture of glass beads and water in a Hele-Shaw cell.

Read more: Sandnes et al.  Labyrinth patterns in confined granular-fluid systems.  Phys. Rev. Lett., 99, 3, 038001 (2007). (Sandnes_prl038001)

Image credit: Bjornar Sandnes

Cracking wet sand


Complex, branching fracture pattern in a system of nothing more than air, sand and water.

Read More:  Campbell et al., Gas-driven fracturing of saturated granular mediaPhys. Rev. Appl. 8, 064029 (2017).

Complex flows, simple rules

Image credit: James Campbell, Bjornar Sandnes

Complex Flow Triptych


Vertical, horizontal and random patterns of frictional fingers in a gravitational potential.

Read more: Eriksen J.A., Toussaint R., Måløy K.J., Flekkøy E.G., Galland O. and Sandnes B. Pattern formation of frictional fingers in a gravitational potentialPhys. Rev. Fluids 3, 013801 (2018). Eriksen_PRFluids2018_preprint

Breaking ground


Injection of air into a water-saturated bed of grains causes fracturing and deformation of the granular packing.

Read more: Campbell et al., Gas-driven fracturing of saturated granular mediaPhys. Rev. Appl. 8, 064029 (2017).

Image credit: James Campbell

Viscous fingering


Injecting water into glycerol produces a beautiful flow pattern due to the difference in viscosity between the two fluids.

Image credit: Clovis Sauzaret, Bjornar Sandnes


Frictional fluid dynamics


Simultaneous flow of gas, liquid and grains produces a spectacular variation in flow patterns. Here, air is injected into a grain-fluid mixture, with the injection rate increasing from left to right.

Read more: Sandnes et al. Patterns and flow in frictional fluidsNature Commun. 2:288 (2011).

Image credit: Bjornar Sandnes


Granular bulldozing


Simulation of granular material on a conveyor belt piling up against a side wall. Arching effects produces a complex frictional response in the compaction zone.

Read more: Marks et al. Compaction of granular material inside confined geometries. Frontiers in Physics 3, 41 (2015).

Image credit: Benjy Marks


Density-driven convection of CO2


When carbon dioxide dissolves in water, the increased density sets up a convective flow pattern that accelerates the rate of CO2 uptake in geologic sequestration processes.

Image credit: Iuri Michel, Bjornar Sandnes


Granular plugs


Plugs of granular material clogging up a tube. The tube is initially filled with water and grains, and the plugs are shaped by a moving meniscus as air invades from left to right.

Read more: Dumazer et al. Frictional fluid dynamics and plug formation in multiphase millifluidic flowPhys. Rev. Lett. 117, 028002 (2016). Synopsis: Forming Granular Plugs

Image credit: Bjornar Sandnes