Abstract

The influence of a magnetic field on the aggregation process of superparamagnetic colloids has been well known on short time for a few decades. However, the influence of important parameters, such as viscosity of the liquid, has received only little attention. Moreover, the equilibrium state reached after a long time is still challenging on some aspects. Indeed, recent experimental measurements show deviations from pure analytical models in extreme conditions. Furthermore, current simulations would require several years of computing time to reach equilibrium state under those conditions. In the present paper, we show how viscosity influences the characteristic time of the aggregation process, with experimental measurements in agreement with previous theories on transient behaviour. Afterwards, we performed numerical simulations on equivalent systems with lower viscosities. Below a critical value of viscosity, a transition to a new aggregation regime is observed and analysed. We noticed this result can be used to reduce the numerical simulation time from several orders of magnitude, without modifying the intrinsic physical behaviour of the particles. However, it also implies that, for high magnetic fields, granular gases could have a very different behaviour from colloidal liquids.

Details

Title
Superparamagnetic colloids in viscous fluids
Author
Darras, A 1 ; Opsomer, E 2 ; Vandewalle, N 3 ; Lumay, G 3 

 GRASP, CESAM - Physics Department, University of Liège, Liège, Belgium; F.R.S.-FRNS, Bruxelles, Belgium; Experimental Physics, Saarland University, Saarbrücken, Germany 
 GRASP, CESAM - Physics Department, University of Liège, Liège, Belgium; Université Paris Diderot, Sorbonne Paris Cité, MSC, CNRS (UMR 7057), Paris, France 
 GRASP, CESAM - Physics Department, University of Liège, Liège, Belgium 
Pages
1-8
Publication year
2017
Publication date
Aug 2017
Publisher
Nature Publishing Group
e-ISSN
20452322
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
1957195584
Copyright
© 2017. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.