Seminar Announcement, 02/14/2017
Levich Institute Seminar Announcement, 02/14/2017
Tuesday, 02/14/2017
2:00 PM
Steinman Hall, Room #312
(Chemical Engineering Conference Room)

Professor Yannick Hallez
Universite Toulouse III Paul Sabatier

"Electrostatic Effects in Suspensions of Hollow Spheres"

ABSTRACT


Charged colloidal hollow spheres can be encountered in nature, e.g. viral capsids, or manufactured for their optical properties or vectorization capabilities. Understanding the electrostatics in suspensions of such particles is necessary to predict their motion at the microscopic scale and their structure at the macroscopic scale, with consequences on thermodynamics and rheology. Here we derive the DLVO-like interaction potential between two hollow spheres, accounting for shell thickness and dielectric permittivity effects. We validate this potential at the pair level thanks to 3D level set simulations of the Poisson-Boltzmann (PB) equation. Predictions of their equation of state with this potential and semi-theoretical methods are also shown to be often very accurate even in concentrated suspensions by comparison with many-body 3D simulations. This is unlike suspensions of full spheres for which many-body corrections beyond the DLVO theory are necessary. We will discuss the reasons for the need (or not) of these corrections for full and hollow spheres.

[ Left: colloidal hollow sphere with salt ions; Right: simulation of a suspension of such colloids with the electric potential field represented qualitatively with color levels. ]





BRIEF ACADEMIC/EMPLOYMENT HISTORY
  • Engineer in Fluid Mechanics from INPT-ENSEEIHT with a specialty in computational fluid mechanics in 2004.
  • Ph.D. and post-doc at IMFT on the topic of confined turbulent gravity currents (e.g. smoke in a tunnel) and viscous gravity currents (e.g. lava flows) (2005-2009).
  • Post-doc at CERFACS on the coupling of massively parallel solid heat transfer and fluid flow codes (application to airplane anti-icing systems) (2009-2010).
  • Assistant Professor at the Laboratoire de Genie Chimique, Toulouse, France in the "interfaces and divided media engineering" department.


RECENT RESEARCH INTERESTS

Electrostatics and hydrodynamics in colloidal suspensions, equations of state, structure and rheology, particle capture during filtration, continuous transport models for colloidal fluids, high performance computing.


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