The turbulent flow in a slug: a re-examination

Cerbus, Rory; Sakakibara, Jun; Gioia, Gustavo; Chakraborty, Pinaki

doi:10.1017/jfm.2019.863

Cited by 5 publications

(2 citation statements)

References 20 publications

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“…Over owed surfaces are subject to counter-rotating foci, separation and saddle points, extinction and even inversion of the velocity, leading to turbulent ows' production, redistribution and dissipation (Ma et al, 2020). Transition from laminar ow to turbulence produces distinct stages of expanding uctuations regions (Cerbus et al, 2019) where large vortices break up to form smaller ones, locally transferring the kinetic energy in a cascading waterfall devoid of long-range transfers (Kalmár-Nagy and Bak, 2019; Ortiz-Suslow and Wang, 2019). The common tenet, based on the Kolmogorov's mean eld theory (Kolmogorov 1941), states that turbulence's multiscale properties are governed by uid viscosity and by the average cascade of kinetic energy transferred from large spatial vortices to small ones (Iyer et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Towards Micro-vortices Generated by Liquid Water’s Structural Heterogeneity

Tozzi

2024

Preprint

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Turbulence is a widespread phenomenon detectable in physical and biological systems. Examining a theoretical model of liquid water flowing in a cylinder at different Raleigh numbers, we propose a novel approach to elucidate the first stages of turbulent flows. The weakly bonded molecular assemblies of liquid distilled water form a fluctuating branched polymer in which every micro-cluster displays different density. Against the common view of liquid water as an incompressible and continuous fluid, we consider it as a non-homogeneous, compressible medium characterised by density differences. We suggest that the occurrence of transient local aggregates in liquid water could produce the vortices and eddies that are the hallmarks of turbulence. As in a two-fluid model, lighter fluid interacts with heavier fluid as if one of the two were an obstacle. Micro-assemblies of such obstacles might justify the presence of micro-vortices and hence of turbulence. We quantify the local changes in velocity, diameter and density required to engender obstacles to the average flow. Then, we explain how these microstructures, equipped with different Raleigh numbers and characterized by high percolation index, could generate boundary layers that contribute to micro-vortices production. We explore the theoretical possibility that three-dimensional turbulence might originate from micro-vortices, contrary to the common view that three-dimensional turbulence is caused by energy cascades from larger to smaller vortices. We conclude that the genesis of turbulence cannot be assessed in terms of collective phenomena, rather is sustained, among many other factors, by the underrated microscopic inhomogeneities of fluids like liquid water.

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Section: Introductionmentioning

confidence: 99%

Towards Micro-vortices Generated by Liquid Water’s Structural Heterogeneity

Tozzi

2024

Preprint

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“…Overflowed surfaces are subject to counter-rotating foci, separation and saddle points, extinction and even inversion of the velocity (Ma et al, 2020) that lead to turbulent flows' production, redistribution and dissipation. Transition from laminar flow to turbulence produces distinct stages of expanding fluctuations regions (Cerbus et al, 2019) where large vortices break up to form smaller ones, locally transferring the kinetic energy in a cascading waterfall devoid of long-range transfers (Kalmár-Nagy and Bak, 2019; Ortiz-Suslow and Wang, 2019).…”

Section: Introductionmentioning

confidence: 99%

Structural and Dynamical Properties of Liquid Water Increase Turbulent Flows

Tozzi¹,

Peters²,

Mariniello³

2022

Preprint

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Turbulence is a fluid dynamic problem refractory to mathematical treatment. Examining a theoretical model of liquid water flowing in a cylinder at different Raleigh numbers, we propose a novel approach to elucidate the first stages of turbulent flows. The weakly bonded molecular assemblies of liquid water form a fluctuating branched polymer in which every micro-cluster displays different density. Against the common view of liquid water as an incompressible and continuous fluid, we suggest that the occurrence of transient local aggregates could be able to generate the vortices and eddies that are the hallmarks of turbulence. We quantify the local changes in velocity, diameter and density required to engender “obstacles” to the average flow. Then, we show how these microstructures, equipped with different Raleigh numbers and characterized by high percolation index, could generate boundary layers that contribute to micro-vortices production. We conclude that the genesis of turbulence cannot be assessed in terms of collective phenomena, rather is sustained, among many other factors, by the underrated microscopic inhomogeneities of fluids like liquid water.

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