DiStruc

ESR15 experimental position with Deniz Gunes: Time-dependent structural dynamics of gels in the presence of gravity effects due to inclusions.

This PhD position is for 3 years (starting Autumn 2015) in partnership between the Nestlé Research Center in Lausanne, Switzerland and Forschungszentrum (FZ) Juelich, Germany. The Nestlé Group is the World’s leading Nutrition, Health and Wellness Company. We offer an attractive and dynamic international working environment with constant opportunities for development, reflecting our conviction that people are our most important asset. FZ Juelich is one of the European leading laboratories on soft matter physics dealing with colloidal physics. 

Topic description 

We want to study both experimentally and theoretically, micro- versus macro-rheological effects in the structural evolution of particle suspensions as affected by the motion of spherical inclusions. Gravity field exerts a pressure on the inclusions which may induce motion, depending on the local rheological properties, and modification of the dynamic behavior of the suspension. The effect of the inclusions on the microstructural evolution of the suspension during macroscopic flow and after flow cessation will be studied, whereby structure may evolve or not until yield stress recovery. The study will include the influence of the macroscopic rheological behavior of the suspension, while particle shape (from spheres to rods or platelets) and interparticle potential will be varied. For the experimental study, we will use model systems consisting of suspensions of particles of well-defined size, shape and interaction potential, as well as systems which are relevant for applications in the food industry (e.g. suspensions of protein or fat particles).  Rheology and rheo-optical techniques will be used, in particular following developments in FZ Juelich and other experts in the field involved in the DiStruc project. Experimental results will be compared to theoretical predictions whenever possible, also in interaction with other groups.

Selection criteria

Candidates should have a strong background and taste in either of Chemical Engineering, Physics, or Material Science disciplines.  Building of robust experimental approaches based on solid theoretical background will be key. Strong drive, organizational and reporting skills in English (fluency in written and oral) are required, combined with team player, open-minded attitude, and curiosity. Specific eligibility and mobility conditions apply.

Applications for this position have now CLOSED

Note that Nestlé participates in DiStruc through funding received from the Swiss State Secreteriat for Education, Research and Innovation (SEFRI).

References

1)Hydrodynamic interactions in rod suspensions with orientational ordering. Lettinga M.P.  et al.,  Soft Matter 6 (18), 4556-4562 (2010)

2)Colloidal microstructure effects on particle sedimentation in yield stress fluids Emady H. et al.,  Journal of Rheology 57 (6), 1761-1772 (2013)

3)Shear induced drainage in foamy yield-stress fluids. Goyon, J. et al., Physical Review Letters 104 (12), 128301 (2010)

4)Flow-induced orientation of non-spherical particles: Effect of aspect ratio and medium rheology. Gunes D.Z. et al., Journal of Non-Newtonian Fluid Mechanics, 155 (1-2), 39-50 (2008)