This title appears in the Scientific Report :
2023
A Shear-Induced Instability in Glass Forming Colloids&Motility-Induced Inter-Particle Correlations and Dynamics
A Shear-Induced Instability in Glass Forming Colloids&Motility-Induced Inter-Particle Correlations and Dynamics
After a short introduction to colloids, in this presentation I will discuss two different phenomena: (i) In the first part, a shear-induced instability is discussed that leads to stable shear-banded flow profiles, as experimentally observed in glass forming colloids. Shear-gradient induced colloidal...
| Personal Name(s): | Dhont, Jan K.G. |
|---|---|
| Contributing Institute: |
Biomakromolekulare Systeme und Prozesse; IBI-4 |
| Imprint: |
2023
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| Conference: | Invited Seminar, Leon (Mexico), 2023-03-19 - 2023-03-22 |
| Document Type: |
Talk (non-conference) |
| Research Program: |
Information Processing in Distributed Systems |
| Publikationsportal JuSER |
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After a short introduction to colloids, in this presentation I will discuss two different phenomena: (i) In the first part, a shear-induced instability is discussed that leads to stable shear-banded flow profiles, as experimentally observed in glass forming colloids. Shear-gradient induced colloidal mass transport from regions of high shear rate towards regions of low shear rate is essential for the occurrence of the instability. After an intuitive picture for the origin of this instability, an expression for the migration velocity of colloids due to spatial gradients in the shear rate is derived. The resulting coupled equations of motion for the colloid concentration and the Navier-Stokes equation are solved analytically [1], which reproduces the shear-banded velocity profiles that are observed experimentally [2]. (ii) Amongst the various theoretical appoaches towards dynamics and phase behaviour of suspensions of active Brownian particles (ABPs), no attempt has been made to specify motility-induced inter-particle correlations. In the second part, a derivation of explicit expressions for the pair-correlation function for ABPs for small and large swimming velocities and low concentrations is discussed. This allows to derive a generalization of Fick’s law for the colloid concentration that includes self-propulsion. It will be shown that there is a concentration-gradient induced preferred swimming direction, due to inter-particle correlations, which tends to stabilize the system against spinodal phase separation [3]. [1] H. Jin, K. Kang, K.-H. Ahn, J.K.G. Dhont, Soft Matter 10 (2014) 9470[2] R. Besseling, L. Isa, P. Ballesta, G. Petekidis, M.E. Cates, W C.K. Poon, Phys. Rev. Lett. 105 (2010) 268301[3] J.K.G. Dhont, G.W. Park, W.J. Briels, Soft Matter 17 (2021) 5613 |