Stable two-layer flows at all Re; visco-plastic lubrication of shear-thinning and viscoelastic fluids

Moyers-González, Miguel; Frigaard, I.A.; Nouar, Chérif

doi:10.1016/j.jnnfm.2010.08.005

Cited by 16 publications

(4 citation statements)

References 42 publications

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“…This results in a finite unyielded region around the central fluid, preserving stability. Both linear and nonlinear stability results have been established, for Newtonian and non-Newtonian core fluids; see Frigaard (2001), Moyers-Gonzalez et al (2004), Moyers-Gonzalez, Frigaard & Nouar (2010), Hormozi et al (2011b) and Hormozi & Frigaard (2012). Experimental studies have used viscous, shear-thinning and viscoelastic core fluids; see Huen et al (2007) and Hormozi et al (2011c).…”

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confidence: 99%

Macro-size drop encapsulation

et al. 2015

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Viscoplastic fluids do not flow unless they are sufficiently stressed. This property can be exploited in order to produce novel flow features. One example of such flows is viscoplastically lubricated (VPL) flow, in which a viscoplastic fluid is used to stabilize the interface in a multi-layer flow, far beyond what might be expected for a typical viscous-viscous interface. Here we extend this idea by considering the encapsulation of droplets within a viscoplastic fluid, for the purpose of transportation, e.g. in pipelines. The main advantage of this method, compared to others that involve capillary forces is that significantly larger droplets may be stably encapsulated, governed by the length scale of the flow and yield stress of the encapsulating fluid. We explore this set-up both analytically and computationally. We show that sufficiently small droplets are held in the unyielded plug of a Poiseuille flow (pipe or plane channel). As the length or radius of the droplets increases, the carrier fluid eventually yields, potentially breaking the encapsulation. We study this process of breaking and give estimates for the limiting size of droplets that can be encapsulated.

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confidence: 99%

Macro-size drop encapsulation

et al. 2015

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“…The above idea is simplistic but effective and has been further studied by [1][2][3][4][5]. In [1] the linear stability of a plane channel geometry with both fluids modeled as Bingham fluids was studied.…”

Section: Introductionmentioning

confidence: 99%

“…1 will not become linearly unstable to interfacial modes. The underlying mapping technique of [1] is applied also in [4], which considers a two-layer channel flow with a yield stress fluid flowing with either a shear-thinning or viscoelastic fluid. The configurations studied ensure an unyielded plug at the interface (eliminating interfacial instability), but also look at the effects of introducing a strong Couette component into the shear-thinning/visco-elastic layer.…”

Section: Introductionmentioning

confidence: 99%