Towards a quantitative understanding of pyroclastic flows: Effects of expansion on the dynamics of laboratory fluidized granular flows

Girolami, Laurence; Druitt, Timothy H.; Roche, Olivier

doi:10.1016/j.jvolgeores.2015.03.008

Cited by 16 publications

(18 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where c1 and c2 were empirical constants that increased with the pore pressure diffusion timescale. Other dam-break experiments with synthetic or pyroclastic material showed that the flow runout and duration increased with the initial amount of material expansion (Girolami et al 2008(Girolami et al , 2015, suggesting that flow deflation increased the pore pressure diffusion timescale, in agreement with experiments on static granular columns (Montserrat et al 2012, Roche 2012. The experiments also revealed that deposition of the particles occurred through progressive aggradation whose rate decreased with the initial material expansion (Girolami et al 2008, Roche 2012.…”

Section: Figure 21supporting

confidence: 72%

The contribution of experimental volcanology to the study of the physics of eruptive processes, and related scaling issues: A review

Roche

Carazzo

2019

Journal of Volcanology and Geothermal Research

View full text Add to dashboard Cite

The experimental approach has become a major tool increasingly used by volcanologists in recent decades to investigate the physics of eruptive processes in complement to field and theoretical works. Researchers have developed various methodologies to study volcanic phenomena at reduced length scale. The works involve natural or analogue materials and their types range from first-order tests, to identify fundamental processes and make qualitative comparison with field observations, to more sophisticated experiments in which precise data obtained in a controlled environment can be used to validate outputs of theoretical models. Scaling is a central issue to ensure dynamic similarity between the small-scale experiments and the large-scale volcanic phenomena when natural conditions cannot be simulated due to inherent length scale difference and/or technical limitations. In this respect, dimensionless numbers are used to map physical regimes and to define scaling laws, which allow experimental results to be extrapolated to natural scale. This review presents the variety of experimental studies conducted to investigate subterraneous and aerial volcanic phenomena involving in particular fluid-particle mixtures. We focus on the major scaling issues and the physical regimes investigated, and we also highlight in a historical perspective some of the major advances achieved through experimental studies. Finally we conclude on some perspectives for future works.

show abstract

Section: Figure 21supporting

confidence: 72%

The contribution of experimental volcanology to the study of the physics of eruptive processes, and related scaling issues: A review

Roche

Carazzo

2019

Journal of Volcanology and Geothermal Research

View full text Add to dashboard Cite

show abstract

“…By assuming that dam-break and particle sedimentation are independent, we derive mathematical expressions that relate together the global characteristics of the phenomenon: front velocity U F , sedimenting velocity U sed , overall flow duration T , height h d∞ and length L of the final deposit. These relations are validated by revisiting previous laboratory experiments conducted with volcanic ash by one of the authors [12][13][14][15].…”

Section: Introductionmentioning

confidence: 69%

“…Surprisingly, the values of U sed and U agg measured during the mixture is flowing are found to be constant both in time and all along the channel [12][13][14][15]. Moreover, they are also equal to those determined in the same mixture sedimenting while confined without flowing within the locked reservoir.…”

Section: Introductionmentioning

confidence: 93%

Physical modeling of the dam-break flow of sedimenting suspensions

Girolami

Risso

2020

Phys. Rev. Fluids

View full text Add to dashboard Cite

We develop a physical model of the dam-break flow of fine non-cohesive particles initially fluidized by a gas. By revisiting previous experiments, we show that the dynamics of such flows involves two uncoupled phenomena. On the one hand, the settling of the particles is the same as that of a non-flowing suspension, so that the mass flux of particles that deposit can be related to the sole properties of the suspension. On the other hand, the flow of the gas-particle mixture is similar to that of an equivalent fluid of constant density and low viscosity. The momentum lost by the flowing mixture is thus the product of the deposited mass flux by the longitudinal velocity. These properties allow us to model the time duration of the flow as the time taken by the particles to settle and the slope of the final deposit as the ratio between the growth rate of the deposit height and the velocity of the front of the dam-break flow. Finally, these findings lead to the formulation of consistent shallow-water equations involving specific terms of mass and momentum transfer at the bottom wall, which can be used to compute the dense lower layer of ash flows generated by a volcanic eruption. They also provide tools for the interpretation of field measurements by geologists.

show abstract

“…Huppert and Simpson 1980;Shin et al 2004) and gas-particle (e.g. Roche et al 2010;Girolami et al 2015) flows resulting from dam break collapse. The densimetric Froude number in the collapse and that in the shear flow are directly related to each other, depending on particle accumulation and 3D air entrainment .…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…This effect depends on higher versus lower particle sedimentation rate, respectively, and it is also clear that the three particle sizes differently contribute to the local sedimentation rate (Valentine et al 2011). On the other hand, the 3D building effect on particle sedimentation is to keep in mind when considering our exponential law for the deposits, in that the buildings certainly affected the particle dispersion by flow Girolami et al (2015) and Lube et al (2015), and with the numerical finding of . In pyroclastic density currents, temperature may be higher in the forced regime instead (Sulpizio et al 2014, p. 57; see also Caricchi et al 2014).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

On the interaction between shear dusty currents and buildings in vertical collapse: Theoretical aspects, experimental observations, and 3D numerical simulation

Doronzo

Tullio

Pascazio

et al. 2015

Journal of Volcanology and Geothermal Research

View full text Add to dashboard Cite

Towards a quantitative understanding of pyroclastic flows: Effects of expansion on the dynamics of laboratory fluidized granular flows

Cited by 16 publications

References 25 publications

The contribution of experimental volcanology to the study of the physics of eruptive processes, and related scaling issues: A review

The contribution of experimental volcanology to the study of the physics of eruptive processes, and related scaling issues: A review

Physical modeling of the dam-break flow of sedimenting suspensions

On the interaction between shear dusty currents and buildings in vertical collapse: Theoretical aspects, experimental observations, and 3D numerical simulation

Contact Info

Product

Resources

About