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

Grant number: 19/10239-7
Support type:Scholarships in Brazil - Doctorate (Direct)
Effective date (Start): August 01, 2019
Effective date (End): July 31, 2023
Field of knowledge:Engineering - Mechanical Engineering - Transport Phenomena
Principal researcher:Erick de Moraes Franklin
Grantee:Willian Righi Assis
Home 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

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
(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)
ASSIS, W. R.; FRANKLIN, E. M. A Comprehensive Picture for Binary Interactions of Subaqueous Barchans. Geophysical Research Letters, v. 47, n. 18 SEP 28 2020. Web of Science Citations: 1.

Please report errors in scientific publications list by writing to: cdi@fapesp.br.