scholarly journals Tracer diffusion in active suspensions

2017 ◽  
Vol 95 (5) ◽  
Author(s):  
Eric W. Burkholder ◽  
John F. Brady
Keyword(s):  
Tracer Diffusion ◽  
Active Suspensions

scholarly journals Lévy fluctuations and mixing in dilute suspensions of algae and bacteria

2011 ◽  
Vol 8 (62) ◽  
pp. 1314-1331 ◽  
Author(s):  
Irwin M. Zaid ◽  
Jörn Dunkel ◽  
Julia M. Yeomans
Keyword(s):  
Graphics Processing Units ◽  
Interaction Model ◽  
Tracer Diffusion ◽  
Theoretical Description ◽  
Active Suspensions ◽  
Tracer Particles ◽  
Dilute Suspensions ◽  
Nutrient Influx ◽  
Non Gaussian ◽  
Micro Organisms

Swimming micro-organisms rely on effective mixing strategies to achieve efficient nutrient influx. Recent experiments, probing the mixing capability of unicellular biflagellates, revealed that passive tracer particles exhibit anomalous non-Gaussian diffusion when immersed in a dilute suspension of self-motile Chlamydomonas reinhardtii algae. Qualitatively, this observation can be explained by the fact that the algae induce a fluid flow that may occasionally accelerate the colloidal tracers to relatively large velocities. A satisfactory quantitative theory of enhanced mixing in dilute active suspensions, however, is lacking at present. In particular, it is unclear how non-Gaussian signatures in the tracers' position distribution are linked to the self-propulsion mechanism of a micro-organism. Here, we develop a systematic theoretical description of anomalous tracer diffusion in active suspensions, based on a simplified tracer-swimmer interaction model that captures the typical distance scaling of a microswimmer's flow field. We show that the experimentally observed non-Gaussian tails are generic and arise owing to a combination of truncated Lévy statistics for the velocity field and algebraically decaying time correlations in the fluid. Our analytical considerations are illustrated through extensive simulations, implemented on graphics processing units to achieve the large sample sizes required for analysing the tails of the tracer distributions.

scholarly journals Loopy Lévy flights enhance tracer diffusion in active suspensions

Nature ◽  
2020 ◽  
Vol 579 (7799) ◽  
pp. 364-367 ◽  
Author(s):  
Kiyoshi Kanazawa ◽  
Tomohiko G. Sano ◽  
Andrea Cairoli ◽  
Adrian Baule
Keyword(s):  
Tracer Diffusion ◽  
Lévy Flights ◽  
Active Suspensions ◽  
Levy Flights

Lithium tracer diffusion in LiNi0.33Mn0.33Co0.33O2 cathode material for lithium-ion batteries

2021 ◽  
Vol 23 (10) ◽  
pp. 5992-5998
Author(s):  
Daniel Uxa ◽  
Helen J. Holmes ◽  
Kevin Meyer ◽  
Lars Dörrer ◽  
Harald Schmidt
Keyword(s):  
Activation Energy ◽  
Cathode Material ◽  
Lithium Ion Batteries ◽  
Lithium Ion ◽  
Tracer Diffusion ◽  
Arrhenius Law

Lithium tracer diffusivities in LiNi0.33Mn0.33Co0.33O2 cathode material for lithium-ion batteries follows the Arrhenius law with an activation energy of 0.85 eV.

Anisotropic diffusion at the field scale in a 4-year multi-tracer diffusion and retention experiment – I: Insights from the experimental data

2014 ◽  
Vol 125 ◽  
pp. 373-393 ◽  
Author(s):  
Thomas Gimmi ◽  
Olivier X. Leupin ◽  
Jost Eikenberg ◽  
Martin A. Glaus ◽  
Luc R. Van Loon ◽  
...  
Keyword(s):  
Experimental Data ◽  
Anisotropic Diffusion ◽  
Tracer Diffusion ◽  
Field Scale

Non-Stoichiometry and Cation Tracer Diffusion Studies in the Magnetite-UlvÖSpinel Solution, (Fe,Ti)3-δO4

1994 ◽  
Vol 369 ◽  
Author(s):  
Sanjeev Aggarwal ◽  
Rudiger Dieckmann
Keyword(s):  
Diffusion Coefficients ◽  
Tracer Diffusion ◽  
Oxygen Activity ◽  
Spinel Solid Solution ◽  
Low Oxygen ◽  
Cation Diffusion ◽  
Deviation From Stoichiometry ◽  
Diffusion Studies ◽  
Tracer Diffusion Coefficients ◽  
Point Defect Structure

AbstractCation diffusion in the spinel solid solution (Fe1-xTix)3-δO4 (0≤ x ≤ 0.3) was investigated at 1200 ºC as a function of oxygen activity, aO2 and cationic composition, x. At different cationic compositions, cation tracer diffusion coefficients, D*Me of Me = Fe and Ti were measured as a function of oxygen activity. Plots of log DMe vs. loga0 show V-shaped curves, indicating that different types of point defects prevail at high anc low oxygen activities. Thermogravimetric experiments were conducted, using a high resolution microbalance, to determine the deviation from stoichiometry in (Fe1-xTix)3-δO4 at 1200 °C. δversus log aO2 curves are S-shaped. An analysis of the oxygen activity dependences of thecation diffusion coefficients and the deviation from stoichiometry with regardto the point defect structure suggests that at high oxygen activities cation vacancies are the predominant defects governing the deviation from stoichiometry and the diffusion ofcations. At low oxygen activities, and at small values of x, cation interstitials determine the deviation from stoichiometry, while they dominate for 0 ≤ x ≤ 0.3 inthe cation diffusion.

Dependence of Diffusion Paths on Thermodynamic Factors in Ternary Systems

2008 ◽  
Vol 277 ◽  
pp. 119-124 ◽  
Author(s):  
Ü. Ugaste ◽  
J. Priimets ◽  
Tony Laas
Keyword(s):  
Approximate Equation ◽  
Ternary Systems ◽  
Diffusion Path ◽  
Tracer Diffusion ◽  
Diffusion Paths ◽  
Slope Function ◽  
Experimental Values ◽  
The Impact ◽  
Tracer Diffusion Coefficients ◽  
Thermodynamic Factors

The impact of thermodynamic factors on deviation from linearity of diffusion path in the ternary system Cu-Fe-Ni is analyzed. For that the slope function of the diffusion path for the diffusion couples 65Ni30Cu5Fe –29.5Ni16.5Cu54Fe, 49.5Ni50.5Fe – 51Ni49Cu and 84Cu16Ni – 50Ni50Fe, annealed at 1000°C for 196h, were calculated by an approximate equation using only thermodynamic data. Results of the calculation were compared with the values of the slope function obtained directly from experimental data. It is shown that despite of the fact that the tracer diffusion coefficients of the components in the system Cu-Fe-Ni are not equal the coincidence between the calculated and experimental values of the slope function is remarkable. This allows us to conclude that at least in this case the deviation of the diffusion path from linearity depends mainly on the thermodynamic properties of the system.

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