Berkeley Fluids Seminar

University of California, Berkeley

Bring your lunch and enjoy learning about fluids!

Monday, November 14, 2016

3110 Etcheverry Hall, 12:00-13:00

Prof. Eliot Fried (OIST, Japan)

Stokesian dynamics of colloidal suspensions in extensional flow

Abstract: Suspensions of micron-size particles in Newtonian fluids are present in a broad spectrum of biological and engineering applications and understanding their rheological properties is a crucial task. Computational studies of such systems are challenging, but important simplifications occur when the Reynolds number is sufficiently small. In this context, the flow equations become linear and Stokesian dynamics simulations offer a feasible pathway for numerical investigations. We will show how it is possible to apply a box-deformation scheme developed by Andersen, Parrinello, and Rahman in the context of molecular dynamics simulations to the Stokesian dynamics of hard spheres suspended in a Newtonian fluid with fixed background flows. Combining that scheme with the box-reinitialization strategy of Kraynik and Reinelt, a perpetual extensional flow can be simulated. We find that in extensional flows simulations, quantities of rheological interest, such as the effective viscosity of the suspension, are robust against computationally-induced ordering. Such ordering, a well-known spurious effect encountered in shear-flow simulations, is easily suppressed in an extensional background flow simply due to the steric interaction of the hard spheres.

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