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The transport of grains as bed-load and the instabilities of a granular bed

Abstract

The transport of granular matter by a fluid flow is frequently found in nature and in industry. It is present, for example, in the erosion of river banks, in the displacement of desert dunes and in hydrocarbon pipelines conveying sand. When the shear stresses exerted by the fluid flow on a granular bed are bounded to some limits, some grains are entrained, but without fluidizing the bed. A mobile granular layer known as bed-load takes place in which the grains stay in contact with the fixed part of the granular bed. Under these conditions, an initially flat granular bed may be unstable, generating ripples and dunes. In the case of rivers, these forms create a supplementary friction between the bed and the water, affecting the water depth and being related to flood and navigation problems. In industry, examples are mostly related to closed-conduit flows conveying grains, such as hydrocarbon pipelines conveying sand. In such cases, bed-forms generate supplementary pressure loss, but also pressure and flow rate transients. Although of importance for many scientific domains, the bed-load and the instabilities of a granular bed are not well understood. This project proposes a theoretical and experimental study concerning the bed-load and the formation of ripples and dunes, contributing to a better knowledge of the subject. The theoretical part will consist of Perturbation Methods, Dimensional Analyses and Stability Analyses for the fluid flow, the bed-load and the bed deformation, respectively. The experimental part will consist of experiments in transparent ducts, where bed-load will occur. The bed-load flow rate, the formation and the migration of ripples and dunes and the fluid flow will be measured by optical techniques. (AU)

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Scientific publications (10)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
MELETTI DE OLIVEIRA, GABRIEL MALTESE; FRANKLIN, ERICK DE MORAES. Transitions between smooth and rough surfaces in turbulent channel flows for d- and k-type rough elements. Journal of the Brazilian Society of Mechanical Sciences and Engineering, v. 40, n. 4 APR 2018. Web of Science Citations: 0.
CUNEZ, FERNANDO DAVID; GOMES DE OLIVEIRA, GABRIEL VICTOR; FRANKLIN, ERICK DE MORAES. Turbulent channel flow perturbed by triangular ripples. Journal of the Brazilian Society of Mechanical Sciences and Engineering, v. 40, n. 3 MAR 2018. Web of Science Citations: 2.
ALVAREZ, CARLOS A.; FRANKLIN, ERICK M. Birth of a subaqueous barchan dune. Physical Review E, v. 96, n. 6 DEC 18 2017. Web of Science Citations: 5.
ALVAREZ, CARLOS A.; FRANKLIN, ERICK DE MORAES. Intermittent gravity-driven flow of grains through narrow pipes. PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS, v. 465, p. 725-741, JAN 1 2017. Web of Science Citations: 3.
MENDES PENTEADO, MARCOS ROBERTO; FRANKLIN, ERICK DE MORAES. Velocity fields of a bed-load layer under a turbulent liquid flow. EXPERIMENTAL THERMAL AND FLUID SCIENCE, v. 78, p. 220-228, NOV 2016. Web of Science Citations: 2.
CARDONA FLOREZ, JORGE EDUAR; FRANKLIN, ERICK DE MORAES. The formation and migration of sand ripples in closed conduits: Experiments with turbulent water flows. EXPERIMENTAL THERMAL AND FLUID SCIENCE, v. 71, p. 95-102, FEB 2016. Web of Science Citations: 4.
FRANKLIN, ERICK DE MORAES. Formation of sand ripples under a turbulent liquid flow. Applied Mathematical Modelling, v. 39, n. 23-24, p. 7390-7400, DEC 2015. Web of Science Citations: 1.
FRANKLIN, ERICK DE MORAES; ZAMBRANO, CARLOS ALVAREZ. Length scale of density waves in the gravitational flow of fine grains in pipes. Journal of the Brazilian Society of Mechanical Sciences and Engineering, v. 37, n. 5, p. 1507-1513, SEP 2015. Web of Science Citations: 2.
FRANKLIN, ERICK DE MORAES; DE FIGUEIREDO, FABIOLA TOCCHINI; ROSA, EUGENIO SPANO. The feedback effect caused by bed load on a turbulent liquid flow. Journal of the Brazilian Society of Mechanical Sciences and Engineering, v. 36, n. 4, p. 725-736, OCT 2014. Web of Science Citations: 4.
FRANKLIN, ERICK DE MORAES; AYEK, GUILHERME AUGUSTO. The perturbation of a turbulent boundary layer by a two-dimensional hill. Journal of the Brazilian Society of Mechanical Sciences and Engineering, v. 35, n. 4, p. 337-346, NOV 2013. Web of Science Citations: 1.

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