Time-dependent simulations of non-axisymmetric patterns in Taylor–Couette flow of dilute polymer solutions

Thomas, Dennis; Al-Mubaiyedh, Usamah A.; Sureshkumar, R.; Khomami, Bamin

doi:10.1016/j.jnnfm.2006.04.013

Cited by 26 publications

(33 citation statements)

References 61 publications

(160 reference statements)

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“…In addition, a diffusive term κ∇ 2 C is added to (2.2) in the bulk flow region to numerically stabilize the integration of the conformation tensor evolution equation. In order to retain the essential dynamics resulting from flow-microstructure coupling while maintaining numerical stability, the value of scalar stress diffusivity κ must be chosen as low as possible (Sureshkumar & Beris 1995;Thomas et al 2006aThomas et al , 2009). Moreover, we have employed a time-adaptive scheme for selecting the value of κ, which corresponds to a numerical Schmidt number Sc −1 κ [=(κRe)] with maximum of O(10 1 ) in all simulations.…”

Section: Problem Formulationmentioning

confidence: 99%

Elastically induced turbulence in Taylor–Couette flow: direct numerical simulation and mechanistic insight

Liu

Khomami

2013

J. Fluid Mech.

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Direct numerical simulation (DNS) of elastically induced turbulent flows has posed great challenges to researchers engaged in developing first-principle models and simulations that can predict faithfully the complex spatio-temporal dynamics of polymeric flows. To this end, DNS of elastically induced turbulent flow states in the Taylor-Couette (TC) flow are reported here with the aim of paving the way for a mechanistic understanding of this new class of flows. Specifically, the DNS not only faithfully reproduce the key feature of elastically induced turbulent flows, namely, substantial excitation of fluid motion at the smallest temporal and spatial scales, but also for the first time demonstrate the existence of three distinct flow regions in the gap for the inertio-elastic turbulence state: (i) a fluid-inertia (or outflow-) dominated inner-wall region; (ii) a fluid-elasticity (or inflow-) dominated outer-wall region; and (iii) an inflow/outflow core region. Based on this observation, a simple mechanism for the inertio-elastic turbulence in the TC flow has been postulated.

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Section: Problem Formulationmentioning

confidence: 99%

Elastically induced turbulence in Taylor–Couette flow: direct numerical simulation and mechanistic insight

Liu

Khomami

2013

J. Fluid Mech.

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“…It is the so-called flame pattern [69][70][71], which can also be observed when inertia and elasticity both play a role [62]. The flame pattern is constituted of 'diwhirls' [73][74][75][76][77][78][79]. The diwhirls are mostly solitary vortex pairs with a very strong and localized inward flow and a very broad and weak outward flow.…”

Section: F Spatiotemporal Dynamics Of the Secondary Flowsmentioning

confidence: 99%

“…We call it 'antiflame' because pairs of vortices can be created in regions of inflow and they can merge but always by the annihilation of counter-rotating vortices separated by an inflow, shaking some of the arguments made on diwhirls [73][74][75][76][77][78][79]. The anti-flame pattern is followed by a steady vortex flow.…”

Section: F Spatiotemporal Dynamics Of the Secondary Flowsmentioning

confidence: 99%

Interplay between elastic instabilities and shear-banding: three categories of Taylor–Couette flows and beyond

et al. 2012

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In the past twenty years, shear-banding flows have been probed by various techniques, such as rheometry, velocimetry and flow birefringence. In micellar solutions, many of the data collected exhibit unexplained spatiotemporal fluctuations. Recently, it has been suggested that those fluctuations originate from a purely elastic instability of the shear-banding flow. In cylindrical Couette geometry, the instability is reminiscent of the Taylor-like instability observed in viscoelastic polymer solutions. The criterion for purely elastic Taylor-Couette instability adapted to shear-banding flows suggested three categories of shear-banding depending on their stability. In the present study, we report on a large set of experimental data which demonstrates the existence of the three categories of shear-banding flows in various surfactant solutions. Consistent with theoretical predictions, increases in the surfactant concentration or in the curvature of the geometry destabilize the flow, whereas an increase in temperature stabilizes the flow. But experiments also exhibit some interesting behaviors going beyond the purely elastic instability criterion.

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“…The nonlinear evolution of finite amplitude disturbances was investigated by performing timedependent simulations using the algorithm explained in Section 3.2. The initial condition was constructed by superimposing, on the steady state, the eigenfunctions associated with the leading eigenmode for the first simulation performed for a given set of geometric/extensibility parameters [2,31]. A weighting factor was selected in order to ensure that the energy contained in the perturbations was small (a few percent) compared to that of the steady state.…”

Section: Nonlinear Stability Analysismentioning

confidence: 99%

“…As discussed by Thomas et al. [2], several methodological and numerical challenges have to be overcome to develop simulations that can faithfully compute such complex viscoelastic flow patterns. In parallel shear flows, such as the plane Couette and channel/tube Poiseuille flow, quasilinear viscoelastic constitutive equations generally predict the base flow to be linearly stable.…”

Section: Introductionmentioning

confidence: 99%

Effect of purely elastic flow instability on molecular conformation and drag

Sadanandan

Sureshkumar

2006

Journal of Non-Newtonian Fluid Mechanics

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Time-dependent simulations of non-axisymmetric patterns in Taylor–Couette flow of dilute polymer solutions

Cited by 26 publications

References 61 publications

Elastically induced turbulence in Taylor–Couette flow: direct numerical simulation and mechanistic insight

Elastically induced turbulence in Taylor–Couette flow: direct numerical simulation and mechanistic insight

Interplay between elastic instabilities and shear-banding: three categories of Taylor–Couette flows and beyond

Effect of purely elastic flow instability on molecular conformation and drag

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