Journal Article

FZJ-2021-02857

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Probing nonlinear velocity profiles of shear-thinning, nematic platelet dispersions in Couette flow using x-ray photon correlation spectroscopy

Chen, Y. ; Korculanin, O.FZJ* ; Narayanan, S.Extern* ; Buitenhuis, J.FZJ* ; Rogers, S. A.Extern* ; Leheny, R. L.Extern* ; Lettinga, M. P. (Corresponding author)FZJ*

2021
American Institute of Physics [S.l.]

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Please use a persistent id in citations: http://hdl.handle.net/2128/28128  doi:10.1063/5.0050942

Abstract: We report experiments employing x-ray photon correlation spectroscopy (XPCS) to characterize the velocity profiles of complex fluids in Couette flow. The approach involves modeling the XPCS correlation functions obtained with the incident x-ray beam passing tangentially through the Couette cell gap at various distances from the inner wall. We first demonstrate the technique with measurements on a dilute colloidal dispersion in the Newtonian liquid glycerol, where the expected linear velocity profiles are recovered. We then employ the technique to map the shear-rate-dependent velocity profiles of a shear-thinning dispersion of nematically ordered Gibbsite platelets. The nonlinear velocity profiles of the Gibbsite dispersion include a narrow slip region adjacent to the outer wall and a band with small velocity gradient in the interior of the gap that evolves into a region increasingly resembling plug flow with increasing shear rate. Variations in the velocity profile along the vorticity direction indicate an instability in the interface between this region of small velocity gradient and a region of high velocity gradient near the inner wall. Analysis of the small-angle scattering patterns provides information about the spatial and temporal variations in the nematic order of the Gibbsite dispersion and their coupling to the velocity profile. Additional potential applications of this XPCS-based technique and comparisons with established methods for characterizing velocity profiles are discussed.

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Contributing Institute(s):

1. Biomakromolekulare Systeme und Prozesse (IBI-4)

Research Program(s):

1. 5243 - Information Processing in Distributed Systems (POF4-524) (POF4-524)

Appears in the scientific report 2021

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Database coverage:
; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; National-Konsortium ; Nationallizenz ; PubMed Central ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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