Ifsttar PhD subject

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Title : Unsaturated Wet Granular Flows: In-Situ X-Ray Microtomography for Studying Liquid Bridge Dynamics Under Shear

Main host Laboratory - Referent Advisor Navier  -  FALL Abdoulaye      tél. : +33 181668475

Director of the main host Laboratory SULEM Jean  -

PhD Speciality Physique

Axis of the performance contract 2 - COP2017 - More efficient and resilient infrastructure

Main location Marne-la-Vallée

Doctoral affiliation UNIVERSITE GUSTAVE EIFFEL

PhD school SCIENCES, INGENIERIE ET ENVIRONNEMENT (SIE)

Planned PhD supervisor FALL Abdoulaye  -    -

Planned financing Contrat doctoral  - Université Gustave Eiffel

Abstract

Background and Problem Statement:
Wet granular materials, comprising solid grains interspersed with liquid bridges or clusters, play a critical role in numerous natural and industrial processes, including soil mechanics, pharmaceuticals, and food processing. These materials exhibit unique mechanical behavior driven by the
interplay between solid grains and liquid phases, particularly in the unsaturated regime where capillary forces dominate. A key challenge in understanding these systems is accurately characterizing the formation and rupture of liquid bridges, which significantly influence the material’s rheological properties under deformation.
Recent advancements in X-ray microtomography developed in our group, combined with image analysis and machine learning techniques, have opened new possibilities for high-resolution 3D
imaging of wet granular flows. However, the dynamics of liquid morphologies and their evolution under shear conditions remain inadequately understood, particularly the transition between different liquid bridge types and the factors that govern their stability and rupture.
This project aims to bridge this gap by studying the dynamics of liquid bridge formation and rupture in wet granular materials using fast X-ray microtomography. By investigating the evolution of liquid morphologies under shear stress, this research will provide insights into the
microstructural changes governing macroscopic flow behavior.
Objectives of the PhD:
The primary objective of this PhD project is to study the dynamic behavior of liquid bridges and other liquid morphologies in unsaturated wet granular flows. Specific goals include:
1. Development of In-situ Experimental Techniques: Create a custom-built shear/compression cell compatible with fast X-ray microtomography, capable of applying controlled mechanical stress to granular samples while performing in-situ imaging.
2. Characterization of Liquid Morphologies: Identify and classify different types of liquid bridges and morphologies in unsaturated granular systems, and analyze their geometrical
and topological properties under various shear deformations.
3. Quantification of Formation and Rupture Mechanisms: Investigate the dynamics of liquid bridge formation, stability, and rupture using fast X-ray microtomography during
shear-induced deformation. Analyze how capillary forces and particle arrangement contribute to the creation and destruction of liquid bridges. This study will include the effects of
parameters such as shear rate, liquid content, and solid particle size.
4. Effect of Shear on Liquid Distribution: Explore the influence of shear stress on the spatial distribution and evolution of liquid morphologies over time, identifying regions of
clustering, dilation, and compaction of liquid phases.
5. Influence of Voxel Size and Image Resolution: Evaluate the impact of voxel size and image resolution on the accuracy of segmentation and quantification of liquid bridges. Address
the challenges posed by finite voxel size in accurately capturing small-scale morphologies.
6. Impact of liquid morphologies on mechanical properties: Relate the dynamic observations of liquid morphologies to the macroscopic response of the granular material (e.g.,
shear strength, dilation) to better understand how microstructures influence the material’s overall properties.
Methodology
1. In-situ experimentation: Develop an experimental setup that allows the application of controlled shear and compression stresses to granular samples while performing real-time
X-ray microtomography. The key component will be a home-made shear device that can be inserted into an X-ray micro-tomograph imager [3, 4]. The device will be designed to provide precise control over stress application and will be used for both laboratory X-ray imaging and experiments at the TOMCAT beamline [7, 5].
2. Fast X-ray microtomography: Use a high-speed X-ray microtomography setup to capture 3D image sequences during shear application on granular samples. Acquisition parameters, such as temporal and spatial resolution, will be optimized to track the rapid evolution of
liquid morphologies.
3. Image processing and segmentation: Apply recent advanced AI-based segmentation techniques, particularly U-Net neural networks, to identify and quantify different liquid morphologies in the 3D images.
4. Statistical and Geometrical Analysis: Quantitative analysis of the liquid bridge morphologies will be performed, exploring correlations between geometric properties, shear rates, and liquid phase evolution.
Expected Outcomes
1. Methodological innovations: Development of an experimental methodology for the dynamic study of liquid morphologies, applicable to other wet granular systems.
2. New insights into liquid morphology dynamics: A deeper understanding of the mechanisms behind the formation and rupture of liquid bridges, and the impact of these phenomena
on the mechanical properties of granular materials.
3. Improved Understanding of Wet Granular Mechanics: Quantitative data on how liquid morphologies affect the macroscopic mechanical behavior of granular materials, leading
to more accurate models for predicting the behavior of unsaturated wet granular flows.
4. Numerical simulation: The experimental data will be used to inform and validate numerical models of wet granular flow. Discrete element method (DEM) simulations [2, 6, 1],
coupled with fluid flow models, will be used to simulate the mechanical response of wet granular materials and to investigate the role of liquid morphologies in force transmission and deformation mechanisms.
Supervision and Collaboration:
The project will be supervised by a scientific committee comprising experts in material mechanics, X-ray imaging, and image processing. Collaborations with laboratories specializing in numerical simulation and granular material rheology are envisaged to complement the experimental approach.
Contact:
Abdoulaye Fall (abdoulaye.fall@univ-eiffel.fr)

References:
[1] Lhassan Amarsid, Ahmad Awdi, Abdoulaye Fall, Jean-Noël Roux, and François Chevoir. Viscous effects in sheared unsaturated wet granular materials. Journal of Rheology, 68(4):523–537, 2024.
[2] M. Badetti, A. Fall, F. Chevoir, and J.-N. Roux. Shear strength of wet granular materials: macroscopic cohesion and effective stress – discrete numerical simulations, confronted to experimental measurements. Eur. Phys. J. E, 41(5):68, 2018.
[3] M. Badetti, A. Fall, D. Hautemayou, F. Chevoir, P. Aimedieu, S. Rodts, and J.-N. Roux. Rheology and microstructure of unsaturated granular materials: Experiments and simulations. J. Rheol., 1175:1175–1186, 2018.
[4] Stephanie Deboeuf, Nicolas Lenoir, David Hautemayou, Michel Bornert, F Blanc, and Guillaume Ovarlez. Imaging non-brownian particle suspensions with x-ray tomography: Application to the microstructure of newtonian and viscoplastic suspensions. Journal of Rheology, 62(2):643–663, 2018.
[5] Hector Dejea, Maria Pierantoni, Gustavo A Orozco, E Tobias B. Wrammerfors, Stefan J Gstöhl, Christian M Schlepütz, and Hanna Isaksson. In situ loading and time-resolved synchrotron-based phase contrast tomography for the mechanical investigation of connective knee tissues: A proof-of-concept study. Advanced Science, page 2308811, 2024.
[6] Saeed Khamseh, Jean-Noël Roux, and François Chevoir. Flow of wet granular materials: A numerical study. Physical Review E, 92(2):022201, 2015.
[7] Julian Link, Bastian Strybny, Thibaut Divoux, Thomas Sowoidnich, Max Coenen, Stefan Gstöhl, Christian M Schlepütz, Marcus Zuber, Steffen Hellmann, Christiane Rößler, et al.
Mechanisms of thixotropy in cement suspensions considering influences from shear history and hydration. ce/papers, 6(6):698–704, 2023.

Keywords : Wet granular materials-Liquid bridges-X-ray microtomography-Machine learning-Rheology

Main host Laboratory - Referent Advisor	Navier - FALL Abdoulaye tél. : +33 181668475
Director of the main host Laboratory	SULEM Jean -
PhD Speciality	Physique
Axis of the performance contract	2 - COP2017 - More efficient and resilient infrastructure
Main location	Marne-la-Vallée
Doctoral affiliation	UNIVERSITE GUSTAVE EIFFEL
PhD school	SCIENCES, INGENIERIE ET ENVIRONNEMENT (SIE)
Planned PhD supervisor	FALL Abdoulaye - -
Planned financing	Contrat doctoral - Université Gustave Eiffel
Abstract Background and Problem Statement: Wet granular materials, comprising solid grains interspersed with liquid bridges or clusters, play a critical role in numerous natural and industrial processes, including soil mechanics, pharmaceuticals, and food processing. These materials exhibit unique mechanical behavior driven by the interplay between solid grains and liquid phases, particularly in the unsaturated regime where capillary forces dominate. A key challenge in understanding these systems is accurately characterizing the formation and rupture of liquid bridges, which significantly influence the material’s rheological properties under deformation. Recent advancements in X-ray microtomography developed in our group, combined with image analysis and machine learning techniques, have opened new possibilities for high-resolution 3D imaging of wet granular flows. However, the dynamics of liquid morphologies and their evolution under shear conditions remain inadequately understood, particularly the transition between different liquid bridge types and the factors that govern their stability and rupture. This project aims to bridge this gap by studying the dynamics of liquid bridge formation and rupture in wet granular materials using fast X-ray microtomography. By investigating the evolution of liquid morphologies under shear stress, this research will provide insights into the microstructural changes governing macroscopic flow behavior. Objectives of the PhD: The primary objective of this PhD project is to study the dynamic behavior of liquid bridges and other liquid morphologies in unsaturated wet granular flows. Specific goals include: 1. Development of In-situ Experimental Techniques: Create a custom-built shear/compression cell compatible with fast X-ray microtomography, capable of applying controlled mechanical stress to granular samples while performing in-situ imaging. 2. Characterization of Liquid Morphologies: Identify and classify different types of liquid bridges and morphologies in unsaturated granular systems, and analyze their geometrical and topological properties under various shear deformations. 3. Quantification of Formation and Rupture Mechanisms: Investigate the dynamics of liquid bridge formation, stability, and rupture using fast X-ray microtomography during shear-induced deformation. Analyze how capillary forces and particle arrangement contribute to the creation and destruction of liquid bridges. This study will include the effects of parameters such as shear rate, liquid content, and solid particle size. 4. Effect of Shear on Liquid Distribution: Explore the influence of shear stress on the spatial distribution and evolution of liquid morphologies over time, identifying regions of clustering, dilation, and compaction of liquid phases. 5. Influence of Voxel Size and Image Resolution: Evaluate the impact of voxel size and image resolution on the accuracy of segmentation and quantification of liquid bridges. Address the challenges posed by finite voxel size in accurately capturing small-scale morphologies. 6. Impact of liquid morphologies on mechanical properties: Relate the dynamic observations of liquid morphologies to the macroscopic response of the granular material (e.g., shear strength, dilation) to better understand how microstructures influence the material’s overall properties. Methodology 1. In-situ experimentation: Develop an experimental setup that allows the application of controlled shear and compression stresses to granular samples while performing real-time X-ray microtomography. The key component will be a home-made shear device that can be inserted into an X-ray micro-tomograph imager [3, 4]. The device will be designed to provide precise control over stress application and will be used for both laboratory X-ray imaging and experiments at the TOMCAT beamline [7, 5]. 2. Fast X-ray microtomography: Use a high-speed X-ray microtomography setup to capture 3D image sequences during shear application on granular samples. Acquisition parameters, such as temporal and spatial resolution, will be optimized to track the rapid evolution of liquid morphologies. 3. Image processing and segmentation: Apply recent advanced AI-based segmentation techniques, particularly U-Net neural networks, to identify and quantify different liquid morphologies in the 3D images. 4. Statistical and Geometrical Analysis: Quantitative analysis of the liquid bridge morphologies will be performed, exploring correlations between geometric properties, shear rates, and liquid phase evolution. Expected Outcomes 1. Methodological innovations: Development of an experimental methodology for the dynamic study of liquid morphologies, applicable to other wet granular systems. 2. New insights into liquid morphology dynamics: A deeper understanding of the mechanisms behind the formation and rupture of liquid bridges, and the impact of these phenomena on the mechanical properties of granular materials. 3. Improved Understanding of Wet Granular Mechanics: Quantitative data on how liquid morphologies affect the macroscopic mechanical behavior of granular materials, leading to more accurate models for predicting the behavior of unsaturated wet granular flows. 4. Numerical simulation: The experimental data will be used to inform and validate numerical models of wet granular flow. Discrete element method (DEM) simulations [2, 6, 1], coupled with fluid flow models, will be used to simulate the mechanical response of wet granular materials and to investigate the role of liquid morphologies in force transmission and deformation mechanisms. Supervision and Collaboration: The project will be supervised by a scientific committee comprising experts in material mechanics, X-ray imaging, and image processing. Collaborations with laboratories specializing in numerical simulation and granular material rheology are envisaged to complement the experimental approach. Contact: Abdoulaye Fall (abdoulaye.fall@univ-eiffel.fr) References: [1] Lhassan Amarsid, Ahmad Awdi, Abdoulaye Fall, Jean-Noël Roux, and François Chevoir. Viscous effects in sheared unsaturated wet granular materials. Journal of Rheology, 68(4):523–537, 2024. [2] M. Badetti, A. Fall, F. Chevoir, and J.-N. Roux. Shear strength of wet granular materials: macroscopic cohesion and effective stress – discrete numerical simulations, confronted to experimental measurements. Eur. Phys. J. E, 41(5):68, 2018. [3] M. Badetti, A. Fall, D. Hautemayou, F. Chevoir, P. Aimedieu, S. Rodts, and J.-N. Roux. Rheology and microstructure of unsaturated granular materials: Experiments and simulations. J. Rheol., 1175:1175–1186, 2018. [4] Stephanie Deboeuf, Nicolas Lenoir, David Hautemayou, Michel Bornert, F Blanc, and Guillaume Ovarlez. Imaging non-brownian particle suspensions with x-ray tomography: Application to the microstructure of newtonian and viscoplastic suspensions. Journal of Rheology, 62(2):643–663, 2018. [5] Hector Dejea, Maria Pierantoni, Gustavo A Orozco, E Tobias B. Wrammerfors, Stefan J Gstöhl, Christian M Schlepütz, and Hanna Isaksson. In situ loading and time-resolved synchrotron-based phase contrast tomography for the mechanical investigation of connective knee tissues: A proof-of-concept study. Advanced Science, page 2308811, 2024. [6] Saeed Khamseh, Jean-Noël Roux, and François Chevoir. Flow of wet granular materials: A numerical study. Physical Review E, 92(2):022201, 2015. [7] Julian Link, Bastian Strybny, Thibaut Divoux, Thomas Sowoidnich, Max Coenen, Stefan Gstöhl, Christian M Schlepütz, Marcus Zuber, Steffen Hellmann, Christiane Rößler, et al. Mechanisms of thixotropy in cement suspensions considering influences from shear history and hydration. ce/papers, 6(6):698–704, 2023.
Keywords :	Wet granular materials-Liquid bridges-X-ray microtomography-Machine learning-Rheology

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