Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Snow globe and other special hydrodynamic features

02.05.2017

Stokes Paradox: How small particles move in water

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.


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

Manfred Schlösser

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

Dr. Manfred Schloesser | Max-Planck-Institut für marine Mikrobiologie
Further information:
http://www.mpi-bremen.de

More articles from Life Sciences:

nachricht Accelerated reactions in condensed bio-matter?
19.06.2018 | Heidelberger Institut für Theoretische Studien gGmbH

nachricht Kidney tumor: Genetic trigger discovered
19.06.2018 | Julius-Maximilians-Universität Würzburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

Im Focus: Photoexcited graphene puzzle solved

A boost for graphene-based light detectors

Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...

Im Focus: Water is not the same as water

Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.

From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Kidney tumor: Genetic trigger discovered

19.06.2018 | Life Sciences

Novel method for investigating pore geometry in rocks

18.06.2018 | Earth Sciences

Diamond watch components

18.06.2018 | Process Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>