Turbulent channel flow of an elastoviscoplastic fluid

Rosti, Marco E.; Izbassarov, Daulet; Tammisola, Outi; Hormozi, Sarah; Brandt, Luca

doi:10.1017/jfm.2018.591

Cited by 38 publications

(61 citation statements)

References 67 publications

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“…Note that, the flow configuration and domain are the same used by Min et al (2001). Figure 3 highly dissipating schemes or with the inclusion of artificial numerical dissipation; in our simulation, we use the high-order WENO scheme for the advection of the conformation tensor and neglect any artificial dissipation, and we find good agreement of the deformation time history over the whole vortex merging process (Rosti & Brandt 2017;De Vita et al 2018;Rosti et al 2018c;Izbassarov et al 2018).…”

Section: Code Validationmentioning

confidence: 72%

Turbulent duct flow with polymers

et al. 2018

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We have performed direct numerical simulation of the turbulent flow of a polymer solution in a square duct, with the FENE-P model used to simulate the presence of polymers. First, a simulation at a fixed moderate Reynolds number is performed and its results compared with those of a Newtonian fluid to understand the mechanism of drag reduction and how the secondary motion, typical of the turbulent flow in non-axisymmetric ducts, is affected by polymer additives. Our study shows that the Prandtl's secondary flow is modified by the polymers: the circulation of the streamwise main vortices increases and the location of the maximum vorticity move towards the center of the duct. In-plane fluctuations are reduced while the streamwise ones are enhanced in the center of the duct and dumped in the corners due to a substantial modification of the quasi-streamwise vortices and the associated near-wall low-and high-speed streaks; these grow in size and depart from the walls, their streamwise coherency increasing. Finally, we investigated the effect of the parameters defining the viscoelastic behavior of the flow and found that the Weissenberg number strongly influences the flow, with the cross-stream vortical structures growing in size and the in-plane velocity fluctuations reducing for increasing flow elasticity. † Email address for correspondence: merosti@mech.kth.se arXiv:1810.06364v1 [physics.flu-dyn]

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Section: Code Validationmentioning

confidence: 72%

Turbulent duct flow with polymers

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“…The numerical code used in this work has been extensively validated in the past for turbulent flow simulations [35][36][37]. Here, we provide one more comparison with literature results for the specific case of a flexible filament.…”

Section: Validationmentioning

confidence: 99%

Flowing fibers as a proxy of turbulence statistics

et al. 2019

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The flapping states of a flexible fiber fully coupled to a three-dimensional turbulent flow are investigated via state-of-the-art numerical methods. Two distinct flapping regimes are predicted by the phenomenological theory recently proposed by Rosti et al. [Phys. Rev. Lett. 121, 044501, 2018]: the under-damped regime, where the elasticity strongly affects the fiber dynamics, and the over-damped regime, where the elastic effects are strongly inhibited. In both cases we can identify a critical value of the bending rigidity of the fiber by a resonance condition, which further provides a distinction between different flapping behaviors, especially in the under-damped case. We validate the theory by means of direct numerical simulations and find that, both for the over-damped regime and for the under-damped one, fibers are effectively slaved to the turbulent fluctuations and can therefore be used as a proxy to measure various two-point statistics of turbulence. Finally, we show that this holds true also in the case of a passive fiber, without any feedback force on the fluid.

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“…In turbulence, where the Reynolds stress is sufficient to break the plug, the behaviour of the YSF resembles a shear-thinning fluid (Güzel et al 2009a) characterized by a reduced wall-normal turbulence intensity. Recently, Rosti et al (2018) simulated the turbulent channel flow of an EVP fluid and observed that in the turbulent regime the friction factor decreases with increasing Bi, until the flow becomes laminar at high Bi.…”

Section: Other Aspects Of Flowing Ysfmentioning

confidence: 99%

Finite-size spherical particles in a square duct flow of an elastoviscoplastic fluid: an experimental study

et al. 2019

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The present experimental study addresses the flow of a Yield Stress Fluid (YSF) with some elasticity (Carbopol gel) in a square duct. The behaviour of two fluids with lower and higher yield stress is investigated in terms of the friction factor and flow velocities at multiple Reynolds numbers Re * ∈ (1, 200) and, hence, Bingham numbers Bi ∈ (0.01, 0.35). Taking advantage of the symmetry planes in a square duct, we reconstruct the entire 3-component velocity field from 2-dimensional Particle Image Velocimetry (PIV). A secondary flow consisting of eight vortices is observed to recirculate the fluid from the core towards the wall-center and from the corners back to the core. The extent and intensity of these vortices grows with increasing Re * or, alternately, as the plug-size decreases. The second objective of this study is to explore the change in flow in the presence of particles. To this end, almost neutrally-buoyant finite-size spherical particles with duct height, 2H, to particle diameter, d p , ratio of 12 are used at two volume fractions φ = 5 and 10%. Particle Tracking Velocimetry (PTV) is used to measure the velocity of these refractive-index-matched spheres in the clear Carbopol gel, and PIV to extract the fluid velocity. Additionally, simple shadowgraphy is also used for qualitatively visualising the development of the particle distribution along the streamwise direction. The particle distribution pattern changes from being concentrated at the four corners, at low flow rates, to being focussed along a diffused ring between the center and the corners, at high flow rates. The presence of particles induces streamwise and wallnormal velocity fluctuations in the fluid phase; however, the primary Reynolds shear stress is still very small compared to turbulent flows. The size of the plug in the particleladen cases appears to be smaller than the corresponding single phase cases. Similar to Newtonian fluids, the friction factor increases due to the presence of particles, almost independently of the suspending fluid matrix. Interestingly, predictions based on an increased effective suspension viscosity agrees quite well with the experimental friction factor for the concentrations used in this study.

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Turbulent channel flow of an elastoviscoplastic fluid

Cited by 38 publications

References 67 publications

Turbulent duct flow with polymers

Turbulent duct flow with polymers

Flowing fibers as a proxy of turbulence statistics

Finite-size spherical particles in a square duct flow of an elastoviscoplastic fluid: an experimental study

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