Fully turbulent flows of viscoplastic fluids in a rectangular duct

Mitishita, Rodrigo S.; MacKenzie, Jordan; Elfring, Gwynn J.; Frigaard, I.A.

doi:10.1016/j.jnnfm.2021.104570

Cited by 14 publications

(4 citation statements)

References 47 publications

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“…3). The difference in scaling between the experimental work (−7/2) 18 and the current study (−2.3) is mainly due to the higher values of Reynolds and Bingham numbers considered here. The abrupt change in the spectra with Bi Λ is consistent with the bulk flow properties (Re Λ and the volume fraction of the unyielded regions Φ) shown in the inset of Fig.…”

contrasting

confidence: 73%

“…Their work revealed that both elasticity and plasticity have similar effects on the near-wall coherent structures, where the flow is characterized by long streaks disturbed for short periods by localized perturbations. A recent experimental study by Mitishita et al 18 on a turbulent duct flow of Carbopol solution de facto verified the numerical results obtained by Rosti et al 16 on the effect of plasticity on the mean flow profile and Reynolds stresses. Additionally, they observed an increase in the energy content Article https://doi.org/10.1038/s41567-023-02018-2…”

supporting

confidence: 62%

“…There are other EVP models that take into account shear-thinning 32 or thixotropic behaviour 33 ; however, we chose the one described above for its simplicity and the least number of involved parameters. Also, this model proved able to capture the main flow characteristics in a turbulent channel flow 16,18 .…”

Section: Methodsmentioning

confidence: 96%

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Scaling and intermittency in turbulent flows of elastoviscoplastic fluids

2023

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Non-Newtonian fluids have a viscosity that varies with applied stress. Elastoviscoplastic fluids, the elastic, viscous and plastic properties of which are interconnected in a non-trivial way, belong to this category. We have performed numerical simulations to investigate turbulence in elastoviscoplastic fluids at very high Reynolds-number values, as found in landslides and lava flows, focusing on the effect of plasticity. We find that the range of active scales in the energy spectrum reduces when increasing the fluid plasticity; when plastic effects dominate, a new scaling range emerges between the inertial range and the dissipative scales. An extended self-similarity analysis of the structure functions reveals that intermittency is present and grows with the fluid plasticity. The enhanced intermittency is caused by the non-Newtonian dissipation rate, which also exhibits an intermittent behaviour. These findings have relevance to catastrophic events in natural flows, such as landslides and lava flows, where the enhanced intermittency results in stronger extreme events, which are thus more destructive and difficult to predict.

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