Inlet effects on roll-wave development in shallow turbulent open-channel flows

Campomaggiore, Francesca; Cristo, Cristiana Di; Iervolino, Michele; Vacca, Andrea

doi:10.1515/johh-2016-0003

Cited by 10 publications

(8 citation statements)

References 32 publications

(42 reference statements)

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“…The roll wave of flow on slopes is initially produced by surface tension. As the water depth and flow velocity increase, the surface tension effect weakens and a "capillary roll wave" is gradually transformed into an "inertial roll wave" (Campomaggiore et al 2016). The inertial roll wave originates from the inertial instability (Brock 1969;Logan and Iverson 2007).…”

Section: Introductionmentioning

confidence: 99%

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Evolution Rules of Rolling Waves on Slopes Based on Artificial Flat Slopes of Loess

et al. 2020

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We used a fixed-bed flume test and ultrasonic sensor measurement technology to study the evolution of the characteristics of thin-layer flow roll waves on a sloped surface. The results indicated that there was a positive correlation between the velocity of the roll wave and the Reynolds number when the energy slope and roughness were small. In addition, the amplitude of the increase gradually decreased with increases in roughness, and the height of the roll waves showed a single-hump trend of change. When the roughness was relatively small, the frequency of the roll waves increased as the Reynolds number increased, and the ratio of the wavelength to the water depth gradually decreased. As the energy slope increased, both the wave velocity and frequency of the roll waves gradually increased; they peaked when the energy slope was 0.3420. We found that the dominant factors that affected different roll-wave characteristic parameters varied. The roughness of the bed had a relatively prominent impact on the velocity of the roll waves, but the energy slope had a greater effect on the height of the roll waves.

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Section: Introductionmentioning

confidence: 99%

“…Because the roll wave has significant impacts on the origination and transportation of sediments on the slope, its prediction is of great interest to the field of environmental engineering (Campomaggiore et al 2016). Harold (1925) and Cornish (1934) were the first to study the roll wave.…”

Section: Introductionmentioning

confidence: 99%

Evolution Rules of Rolling Waves on Slopes Based on Artificial Flat Slopes of Loess

et al. 2020

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“…For very small p values, the governing equations may be linearized in the neighborhood of the uniform flow condition and analytically solved. The solution is known for the clear-water case, both for constant (Supino, 1960) or variable (Campomaggiore et al, 2016b) friction factor, and it has been previously used as a benchmark for numerical methods aimed to reproduce roll-waves development (Zanuttigh and Lamberti, 2002;Campomaggiore et al, 2016b). This solution has been herein further extended to account for the features of the present flow model, namely the momentum coefficient and the different rheological behavior.…”

Section: Numerical Methods Validationmentioning

confidence: 99%

“…For clear-water flows in turbulent regime, it is widely accepted that the essential features of natural rollwaves train may be reproduced by forcing the shallow water model with a random noise at the inlet. It was shown that both fully hyperbolic (Zanuttingh and Lamberti, 2002;Campomaggiore et al, 2016b) or diffusive (Chang et al, 2000;Huang and Lee, 2015a,b;Cao et al, 2015) models are able to predict the main properties of the roll-waves spatial evolution experimentally observed by Brock (1967). In particular, Brock (1967) observed that the initial development of the phenomenon showed an exponential growth of the perturbations.…”

Section: Introductionmentioning

confidence: 93%

A Strategy for Passive Control of Natural Roll-Waves in Power-Law Fluids through Inlet Boundary Conditions

Cristo

Iervolino

Vacca

2017

JAFM

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The paper investigates the influence of the inlet boundary condition on the spatial evolution of natural rollwaves in a power-law fluid flowing in steep slope channels. The analysis is carried out numerically, by solving the von Kármán depth-integrated mass and momentum conservation equations, in the long-wave approximation. A second-order accurate scheme is adopted and a small random white-noise is superposed to the discharge at the channel inlet to generate the natural roll-waves train. Both shear-thinning and shearthickening power-law fluids are investigated, considering uniform, accelerated and decelerated hypercritical profiles as the unperturbed condition. Independently of the unperturbed profile and of the fluid rheology, numerical simulations clearly enlighten the presence of coalescence, coarsening and overtaking processes, as experimentally observed. All the considered statistical parameters indicate that the natural roll-waves spatial evolution is strongly affected by the unperturbed profile. Compared with the uniform condition, at the beginning of roll-waves development an accelerated profile reduces the growth of the roll-waves with a downstream shift of the non-linear wave interaction. The opposite behavior is observed if the roll wave train develops over a decelerated profile. The comparison with the theoretical outcomes of the linearized near wave-front analysis allows the interpretation of this result in terms of stability of the base flow. It is shown that once the coarsening process starts to take place, the roll-waves spatial growth rate is independent of the unperturbed profile. Present results suggest that an appropriate selection of the flow depth at the channel inlet may contribute to control, either enhancing or inhibiting, the formation of a roll-waves train in power-law fluids.

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“…Through time, chiefly in the last 15 years, the roll wave phenomenon has been reported in the physics literature (Liu & Mei, 1994;Liu & Gollub, 1994;Needham & Merkin, 1987;Hwang & Chang, 1987;Gao et al, 2003), in chemistry (Holmås, 2010), in engineering (He et al, 2020;Mcardell, 2016) and in applied mathematics (Razis et al, 2019;Campomaggiore et al, 2016), under three self-complementary branches: mathematical, numerical and experimental modelling. This reaffirms the multiinter-transdisciplinary aspect of the subject, reflecting in the opportunity/possibility to gather around different researchers (Balmforth, 2011), (e) Channelized Achumani River, La Paz (Ponce & Guzmán, 2019).…”

Section: Introductionmentioning

confidence: 99%

Roll waves and their generation criteria

Ferreira

Maciel

Pereira

2021

RBRH

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Pulsating waves (also known as roll waves) might occur on the free surface of extreme events like mud and debris flows, among others, usually intensifying the caused damage. This technical note aims to inform about the roll wave phenomenon developing in a free-surface laminar flow, and analyze its generation criteria, centered on the concepts of Froude number and disturbance frequency. The complete linear stability analysis of the new depth-averaged model was proven a useful theoretical tool in determining new generation criteria for roll waves developing in non-Newtonian fluids. The results showed that the roll wave generation depends on two criteria: the first is associated to the minimum Froude number, and the second is related to the cut-off frequency. In addition, we have confirmed that the new generation criteria can be verified via numerical simulation based on a second model with full equations (Fluent software). Globally, the emergence of roll waves is favored by the non-Newtonian properties of the flowing fluid and the fact that the cut-off frequency decreases along with the minimum Froude number. Lastly, both generation criteria were tested in order to examine a case study involving the occurrence of roll waves in a watershed.

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Inlet effects on roll-wave development in shallow turbulent open-channel flows

Cited by 10 publications

References 32 publications

Evolution Rules of Rolling Waves on Slopes Based on Artificial Flat Slopes of Loess

Evolution Rules of Rolling Waves on Slopes Based on Artificial Flat Slopes of Loess

A Strategy for Passive Control of Natural Roll-Waves in Power-Law Fluids through Inlet Boundary Conditions

Roll waves and their generation criteria

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