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Article Dans Une Revue Journal of the Acoustical Society of America Année : 2020

Ultrasonic backscattering and microstructure in sheared concentrated suspensions

Julien Rouyer
  • Fonction : Auteur
Eric Debieu
  • Fonction : Auteur
Frédéric Blanc
Emilie Franceschini

Résumé

Quantitative ultrasound techniques based on the parametrization of the backscatter coefficient (BSC) are used to characterize concentrated particle suspensions. Specifically, a scattering model is fit to the measured BSC and the fit parameters can provide local suspension properties. The scattering models generally assume an isotropic microstructure (i.e., spatial organization) of the scatterers, whereas the sheared concentrated suspensions can develop an anisotropic microstructure. This paper studied the influence of the shear-induced anisotropic microstruc-ture of concentrated suspensions on the ultrasonic backscattering. Experiments were conducted on suspensions of polymethylmetacrylate spheres (5.8 um in radius) sheared in a Couette flow device to obtain anisotropic microstruc-ture and then mixed by hand to obtain isotropic microstructure. Experimental structure factors that are related to the spatial distribution of sphere positions were obtained by comparing the BSCs of one concentrated and one diluted suspension. Finally, Stokesian dynamics numerical simulations of sheared concentrated suspensions are used to determine the pair correlation function, which is linked to the Fourier transform of the structure factor. The experimental structure factors are found to be in good agreement with numerical simulations. The numerical simulation demonstrates that the angular-dependent BSCs and structure factors are caused by the shear-induced anisotropic microstructure within the suspension.
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Dates et versions

hal-03005581 , version 1 (14-11-2020)

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Olivier Lombard, Julien Rouyer, Eric Debieu, Frédéric Blanc, Emilie Franceschini. Ultrasonic backscattering and microstructure in sheared concentrated suspensions. Journal of the Acoustical Society of America, 2020, 147, pp.1359 - 1367. ⟨10.1121/10.0000803⟩. ⟨hal-03005581⟩
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