Snow globe and other special hydrodynamic features

Snow globes. The motion of small flocks in this toy are hardly calculable, specially the ones which are cylindrically shaped. Manfred Schlösser

Consider a snow globe. When shaken, the tiny flakes and particles are set into motion and “it snows”. What lights up kid’s eyes has been a long standing puzzle for scientists, as there has been no consensus on how particles with shapes other than spheres, for example cylinders, settle though water.

This problem is, however, of great relevant and finds application also in the climate research. Now, scientists from Max Planck Institute for Marine Microbiology, Germany have shed light onto this problem, and present a solution.

Scientists, for example, climate researchers and engineers are interested in the sinking of particles in water columns of lakes and oceans. These particles can appear in the form similar to sphere, cylinder and other shapes. Cylindrical organisms with a large length to diameter ratio are quite ubiquitous in the world’s oceans. Such examples are diatoms, fecal pellets and green algae.

The British scientist Sir George Gabriel Stokes found in 19th century a relation for the drag experienced by a solid sphere moving in viscous fluid. Nevertheless, he failed to obtain a solution for a solid cylinder, He further postulated that a rigorous mathematical solution for this problem does not exist, which was referred to as “Stokes’ Paradox” by subsequent researchers. Until now, all approximations presented deviated drastically from one another. Areal consensus appeared unachievable.

While studying the sinking behavior of the dead marine organisms to the sea floor, Arzhang Khalili and Bo Liu from the Max Planck Institute for Marine Microbiology in Bremen found a solution to “Stokes’ Paradox”, and present their results in the Journal of Fluid Mechanics.

How quickly particles sink to the sea floor is of interest to climate researchers, because microorganisms contain bound carbon, which originate from microscopic organisms using photosynthesis. The necessary carbon dioxide comes from the atmosphere.

“With the relation presented by us one can one can calculate carbon balances more accurately’’, says Arzhang Khalili, also Adjunct Professor at Jacobs University Bremen. “When we compared the different available solution of Stokes’ paradox with experimental data no agreement could be found. Only extensive and accurate numerical computer simulation led to successful results.”
And what about the snow globe? One can enjoy watching it without mathematics.

Original publication:

Khalili, A., & Liu, B. (2017). Stokes’ paradox: Creeping flow past a two-dimensional cylinder in an infinite domain. Journal of Fluid Mechanics, 817, 374-387. doi:10.1017/jfm.2017.127

Questions maybe addressed to:


Prof. Dr. Arzhang Khalili
Max-Planck-Institut für Marine Mikrobiologie
Celsiusstraße 1, 28359 Bremen
Te­le­fon: +49 421 2028 636

E-Mail: akhalili(at)mpi-bre­men.de


or to the press office
Dr. Manfred Schlösser
Dr. Fanni Aspetsberger

Phone: +49 421 2028 704

E-Mail: presse(at)mpi-bremen.de

Media Contact

Dr. Manfred Schloesser Max-Planck-Institut für marine Mikrobiologie

More Information:

http://www.mpi-bremen.de

All latest news from the category: Life Sciences and Chemistry

Articles and reports from the Life Sciences and chemistry area deal with applied and basic research into modern biology, chemistry and human medicine.

Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors