Avalanche Behavior in Yield Stress Fluids

Coussot, Philippe; Nguyen, Quoc‐Hung; Huynh, Hieu Thao; Bonn, Daniel

doi:10.1103/physrevlett.88.175501

Cited by 421 publications

(405 citation statements)

References 19 publications

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“…Coussot et al [44] provided evidence for an interplay between yield stress and thixotropy. Møller et al [45] concluded that yield stress and thixotropy of a fluid have the same physical origin.…”

Section: Rheometrymentioning

confidence: 99%

Experimental investigation of the spreading of viscoplastic fluids on inclined planes

Cochard

Ancey

2009

Journal of Non-Newtonian Fluid Mechanics

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a b s t r a c tWe report experimental results related to the dam-break problem for viscoplastic fluids. Using image processing techniques, we were able to accurately reconstruct the free-surface evolution of fixed volumes of fluid suddenly released a plane. We used Carbopol Ultrez 10 as a viscoplastic material; its rheological behavior was closely approximated by a Herschel-Bulkley model for a fairly wide range of shear-rates. Varying the Carbopol concentration allowed us to change the yield stress and bulk viscosity. The yield stress ranged from 78 to 109 Pa, producing Bingham numbers in the 0.07-0.35 range. We investigated the behavior of a 43-kg mass released on a plane, whose inclination ranged from 0 • to 18 • . For each run, we observed that the behavior was nearly the same: at short times, the mass accelerated vigorously on gate opening and very quickly reached a nearly constant velocity. At time t = 1 s, independently of plane inclination and yield stress, the mass reached a near-equilibrium regime, where the front position varied as a power function of time over several decades. We did not observe any run-out phase, during which the mass would have gradually come to a halt. The similarity in the flow behavior made it possible to derive an empirical scaling for the front position in the form x f = t 0.275(sin˛) 1/3 (sin˛) 5/4 , where˛and t denote plane inclination and time, respectively, and which holds for sloping beds (˛> 0).

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Section: Rheometrymentioning

confidence: 99%

Experimental investigation of the spreading of viscoplastic fluids on inclined planes

Cochard

Ancey

2009

Journal of Non-Newtonian Fluid Mechanics

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“…As with the Herschel-Bulkley model on which it is based, the Papanastasiou model is time-independent. In contrast, the time-dependent (thixotropic) model of Coussot et al (2002a) introduces dependency on a timevarying microstructure parameter (λ) in the general form…”

Section: Non-newtonian Fluid Modelsmentioning

confidence: 99%

“…-Method A: assuming all other parameters of the fluid are known, including the critical stress τ c , the initial condition, λ 0 , can be evaluated using the Coussot equation for the critical stress as (Coussot et al, 2002a):…”

Section: Estimation Of Parameters For Time-dependent Coussot Modelmentioning

confidence: 99%

“…Thus, in a thixotropic fluid there is spatial-temporal destruction of microstructure that leads to changes in the effective viscosity that cannot be represented in the standard time-independent models. Coussot et al (2002a) proposed an empirical viscosity model for thixotropic fluids (presented in detail in Sect. 3, below), which captures these fundamental behaviors.…”

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confidence: 99%

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Comparing thixotropic and Herschel–Bulkley parameterizations for continuum models of avalanches and subaqueous debris flows

Jeon

Hodges

2018

Nat. Hazards Earth Syst. Sci.

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Abstract. Avalanches and subaqueous debris flows are two cases of a wide range of natural hazards that have been previously modeled with non-Newtonian fluid mechanics approximating the interplay of forces associated with gravity flows of granular and solid-liquid mixtures. The complex behaviors of such flows at unsteady flow initiation (i.e., destruction of structural jamming) and flow stalling (restructuralization) imply that the representative viscositystress relationships should include hysteresis: there is no reason to expect the timescale of microstructure destruction is the same as the timescale of restructuralization. The nonNewtonian Herschel-Bulkley relationship that has been previously used in such models implies complete reversibility of the stress-strain relationship and thus cannot correctly represent unsteady phases. In contrast, a thixotropic nonNewtonian model allows representation of initial structural jamming and aging effects that provide hysteresis in the stress-strain relationship. In this study, a thixotropic model and a Herschel-Bulkley model are compared to each other and to prior laboratory experiments that are representative of an avalanche and a subaqueous debris flow. A numerical solver using a multi-material level-set method is applied to track multiple interfaces simultaneously in the simulations. The numerical results are validated with analytical solutions and available experimental data using parameters selected based on the experimental setup and without post hoc calibration. The thixotropic (time-dependent) fluid model shows reasonable agreement with all the experimental data. For most of the experimental conditions, the HerschelBulkley (time-independent) model results were similar to the thixotropic model, a critical exception being conditions with a high yield stress where the Herschel-Bulkley model did not initiate flow. These results indicate that the thixotropic relationship is promising for modeling unsteady phases of debris flows and avalanches, but there is a need for better understanding of the correct material parameters and parameters for the initial structural jamming and characteristic time of aging, which requires more detailed experimental data than presently available.

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“…É importante notar que existe um tempo mínimo necessário para a amostra sair do nível de tensão inicial e começar a quebrar a microestrutura, para então iniciar o escoamento. Este tempo é referido na literatura como tempo de avalanche (97). …”

Section: Experimento De Destruiçãounclassified

Um Modelo Constitutivo Fenomenológico Irreversível Para Descrição Reológica De Pastas De Cimento

RODRIGUES¹

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Ao meu orientador Paulo Roberto de Souza Mendes pela honra de desenvolver pesquisa em nível internacional ao seu lado, pelo acompanhamento desse trabalho, especialmente pelos valiosos ensinamentos, discussões e a oportunidade de aprimorar meus conhecimentos.A Flávio H. Marchesini por me inserir no mundo da Reologia e Rafael M. Oliveira pelas muitas discussões físicas e numéricas.Aos professores do Departamento de Engenharia Mecânica pelos cursos ministrados.Aos colegas do Greo (Grupo de Reologia) pela troca de experiência, discussões e pelos momentos espirituosos que tornaram esse trabalho menos árduo, em particular a Bruno Fonseca, Behbood Abedi, Eliana Marin, Luiz Sica, Paulo Henrique, Pedro Tobar, Priscilla Varges, Ricardo Leite, Aline Abdu, Roberta Kamei e William Candela.À Carina Beline pela ajuda nos trâmites administrativos necessários para conclusão dessa tese.A Petrobras, CAPES e à PUC-Rio, pelos auxílios concedidos, sem os quais esse trabalho não poderia ter sido desenvolvido.À minha esposa Gabriela, fundamental nessa etapa da minha vida. Obrigado por me ajudar a ultrapassar os obstáculos que enfrentei, pela compreensão, cumplicidade, carinho e apoio ao longo de todo esse tempo. Te amo.À minha mãe, pela resiliência que a vida lhe impôs, me permitindo chegar até aqui, obrigado por ser quem é e pelo amor incondicional. Te amo. A performance de protocolos geralmente empregados na caracterização reológica de pastas de cimento é investigada. Para este fim duas pastas de cimento foram utilizadas, Pasta A e Pasta B, com a mesma densidade e razão água-cimento, diferindo quanto aos aditivos empregados. O procedimento API (American Petroleum Institute), tal qual, sua modificação é estudada. Curvas de escoamento são determinadas com o auxílio de um reômetro rotacional através de três diferentes métodos (ramp up/ramp down, ramp down e viscosidade mínima). O procedimento API gerou curvas de escoamento que superestimaram (Pasta A) ou subestimaram (Pasta B) a viscosidade dentro da faixa de cisalhamento estudada. Os desvios tornam-se particulamente maiores em baixas taxas, e para Pasta B, por causa de efeitos tixotrópicos, o regime permanente não é atingido. A modificação do protocolo API investigada resultou em curvas de escoamento similares ao método de viscosidade mínima. Um novo modelo constitutivo fenomenológico irreversível é proposto para descrição reológica de pastas de cimento (voltadas para poços de petróleo) sob escoamento de cisalhamento simples. Para esse objetivo uma série de experimentos foram realizados, como taxa de deformação constante, construção e destruição da microestrutura. O modelo proposto utiliza a própria fluidez, recíproca da viscosidade, para descrever a evolução da estrutura da pasta. O efeito macroscópico do fenômeno de hidratação na reologia é introduzido por meio de uma função exponencial para tensão limite de escoamento. Todos os dez parâmetros necessários no modelo são experimentalmente obtíveis. Os resultados mostraram boa concordância entre os dados experimentais e a modelagem, emb...

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Avalanche Behavior in Yield Stress Fluids

Cited by 421 publications

References 19 publications

Experimental investigation of the spreading of viscoplastic fluids on inclined planes

Experimental investigation of the spreading of viscoplastic fluids on inclined planes

Comparing thixotropic and Herschel–Bulkley parameterizations for continuum models of avalanches and subaqueous debris flows

Um Modelo Constitutivo Fenomenológico Irreversível Para Descrição Reológica De Pastas De Cimento

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