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Bed-load instabilities: granular dynamics and interaction with the fluid flow

Grant number: 19/10239-7
Support Opportunities:Scholarships in Brazil - Doctorate (Direct)
Start date: August 01, 2019
End date: November 30, 2023
Field of knowledge:Engineering - Mechanical Engineering - Transport Phenomena
Principal Investigator:Erick de Moraes Franklin
Grantee:Willian Righi Assis
Host Institution: Faculdade de Engenharia Mecânica (FEM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
Associated research grant:18/14981-7 - Modeling of dense granular flows: experiments, numerical simulations and stability analyses, AP.JP2
Associated scholarship(s):21/12910-8 - Segregation of polydisperse particles during dune-dune interaction, BE.EP.DD

Abstract

The transport of granular matter by a turbulent flow is frequent in both nature and industry. Some examples are sand transport by wind in deserts and beaches, sand transport by water in rivers and oceans, and sand transport in pipes such as happens in water pipes, sewer systems and oil pipelines. For horizontal flows, granular matter can be entrained as a moving layer, known as bed load, which keeps contact with the fixed part of the bed. Under certain conditions, the granular bed may deform, giving rise to ripples and dunes. This is an intricate problem: the rise of bedforms disturbs the fluid flow, which in its turn is the responsible for their growth. Although many studies were previously devoted to this problem, the formation and migration of sand dunes is still an open problem. This PhD thesis consists in an experimental investigation of the formation and dynamics of dunes under turbulent flows. The experiments will measure the dunes at both the grain and dune scales and the fluid flow. The displacements of individual grains over the dunes will be determined by using a high-speed camera together with image treatment to compute the trajectories of individual grains. With this, we will obtain typical lengths and velocities of individual grains. For the morphology, the bed will be filmed with a high-resolution camera, and an image processing code will identify the formation of patterns and determine their wavelength, celerity and growth rate. The fluid flow will be measured with a low frequency (4 Hz) PIV device (Particle Image Velocimetry) together with high-frequency visualization by using a continuous laser and a high-speed camera. With this, we will obtain the main characteristics of the turbulent flow (mean velocities, second order moments, etc.). (AU)

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Scientific publications (8)
(The scientific publications listed on this page originate from the Web of Science or SciELO databases. Their authors have cited FAPESP grant or fellowship project numbers awarded to Principal Investigators or Fellowship Recipients, whether or not they are among the authors. This information is collected automatically and retrieved directly from those bibliometric databases.)
ASSIS, W. R.; FRANKLIN, E. M.. A Comprehensive Picture for Binary Interactions of Subaqueous Barchans. Geophysical Research Letters, v. 47, n. 18, . (19/10239-7, 18/14981-7)
ASSIS, W. R.; CUNEZ, F. D.; FRANKLIN, E. M.. Revealing the Intricate Dune-Dune Interactions of Bidisperse Barchans. JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE, v. 127, n. 5, p. 14-pg., . (16/18189-0, 18/14981-7, 19/10239-7)
ASSIS, W. R.; FRANKLIN, E. M.; VRIEND, N. M.. Evolving Dunes Under Flow Reversals: From an Initial Heap Toward an Inverted Dune. JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE, v. 130, n. 2, p. 15-pg., . (21/12910-8, 19/10239-7, 18/14981-7)
LIMA, N. C.; ASSIS, W. R.; BORGES, D. S.; FRANKLIN, E. M.. Barchans Interacting With Dune-Size Obstacles: Details of the Fluid Flow and Motion of Grains. JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE, v. 130, n. 6, p. 17-pg., . (19/10239-7, 22/01758-3, 18/14981-7, 19/20888-2)
ASSIS, WILLIAN R.; BORGES, DANILO S.; FRANKLIN, ERICK M.. On the effect of two-direction seasonal flows on barchans and the origin of occluded dunes. Geomorphology, v. 467, p. 8-pg., . (18/14981-7, 19/10239-7, 22/01758-3)
LIMA, N. C.; ASSIS, W. R.; ALVAREZ, C. A.; FRANKLIN, E. M.. Barchan-Barchan Dune Repulsion Investigated at the Grain Scale. JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE, v. 129, n. 8, p. 14-pg., . (19/20888-2, 18/14981-7, 19/10239-7)
ASSIS, W. R.; BORGES, D. S.; FRANKLIN, E. M.. Barchan Dunes Cruising Dune-Size Obstacles. Geophysical Research Letters, v. 50, n. 14, p. 7-pg., . (18/14981-7, 19/10239-7, 22/01758-3)
LIMA, NICOLAO C.; ASSIS, WILLIAN R.; ALVAREZ, CARLOS A.; FRANKLIN, ERICK M.. Grain-scale computations of barchan dunes. Physics of Fluids, v. 34, n. 12, p. 15-pg., . (18/14981-7, 19/20888-2, 19/10239-7)
Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
ASSIS, Willian Righi. Dinâmica da interação de barcanas subaquáticas. 2023. Doctoral Thesis - Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Mecânica Campinas, SP.