Patrick Pizette

• PhD
• Professor (Associate) at IMT Nord Europe

Numerical simulation of particulate materials is required in many industrial processes with applications ranging from ball mills in mining to powder mixers in pharmaceuticals. While the discrete element method (DEM) has become the defacto standard for numerical simulation of particulate materials, the large computational cost associated with the me...

This work describes a comparative study on the milling process modelled by Discrete Element Method and lab-scale experiments. In particular, analogical complex granular media with spherical and polyhedral shaped particles have been used to support the development of Blaze-DEM GPU, which is graphical processor unit (GPU) based computing framework fo...

We recently introduced Blaze-DEMGPU, a GPU based computing framework for convex polyhedral shaped particles (Govender et al. Appl. Math. Comp. 267, 810–829, 2015). The computing framework was validated against numerous industrial applications that include particulate discharge and estimating power draw for a ball mill in comminution applications. I...

The importance of shape non-uniformity and the polydispersed nature of granular media in industrial hopper discharge applications has been well established experimentally. Although numerous hopper discharge simulations have been conducted over the last thirty years, the investigations into the non-uniformity of particle shape and the polydisperse n...

This work describes a post-processing scheme for multiphase flow systems to characterize primary atomization. The scheme relies on the 2D fast Fourier transform (FFT) to separate the inherently multi-scale features present in the flow results. Emphasis is put on the robust quantitative analysis enabled by this scheme, with this work specifically fo...

This paper presents a GPU-based, incompressible, multiphase generalized finite difference solver for simulating multiphase flow. The method includes a dampening scheme that allows for large density ratio cases to be simulated. Two verification studies are performed by simulating the relaxation of a square droplet surrounded by a light fluid and a b...

This work investigates the effects of the choice of momentum diffusion operator on the evolution of multiphase fluid systems resolved with Meshless Lagrangian Methods (MLM). Specifically, the effects of a non-zero viscosity gradient at multiphase interfaces are explored. This work shows that both the typical Smoothed Particle Hydrodynamics (SPH) an...

Developing ecofriendly bricks using natural material such as clay represents an essential step toward making building sector low cost and energy efficient. This study aims to describe the physicochemical characterization and rheological property of clay taken from Gafsa, Tunisia. The rheology of clay–water mixtures was determined to understand the...

An under-resolved coupling strategy for the discrete element method (DEM) and the weakly compressible (WC) generalised finite difference method (GFD) is proposed. A novel filtering technique is proposed that allows for the recovery of a continuum porosity field in an arbitrary domain from DEM information. This allows fine spherical DEM particles to...

This paper introduces a boundary condition scheme for weakly compressible (WC) renormalised first-order accurate meshless Lagrangian methods (MLM) by considering both solid and free surface conditions. A hybrid meshless Lagrangian method-finite difference (MLM-FD) scheme on prescribed boundary nodes is proposed to enforce Neumann boundary condition...

The Discrete Element Method (DEM) has been successfully used to further understand GM behaviour where experimental means are not possible or limited. However, the vast majority of DEM publications use simplified spheres with rolling friction to account for particle shape, with a few using clumped spheres and super quadratics to better capture grain...

The use of the Discrete Element Method to model engineering structures implementing granular materials has proven to be an efficient method to response under various behaviour conditions. However, the computational cost of the simulations increases rapidly, as the number of particles and particle shape complexity increases. An affordable solution t...

This paper aimed at an experimental study carried out in a laboratory on calcite sand in order to characterize the behavior of the granular media using oedometric tests. Enormous quantities of this type of material exist in nature. In addition, it is the most used in various industrial sectors, especially in civil engineering in such fields as the...

This article presents the results of a numerical simulation carried out from a series of standard triaxial tests conducted on limestone sand from a quarry situated in Algiers (center of Algeria). The main objective of the investigation is to obtain from a numerical analysis a simple soil model to represent the behaviour of the studied material. The...

Calibration remains an important challenge in the estimation of discrete element parameters. Importantly, the usability of the discrete element method (DEM) is directly dependent on the quality of the parameter estimation. Numerous approaches have been developed to characterize discrete element parameters directly from experimental data, often char...

Abstract : In this paper, we are showing a laboratory test of clay soil from different locality of Tunisia and its behavior under static compaction test. The static pressing of clay soil is well used in ceramic construction especially to produce earth-compressed bricks. Laboratory test of the static compaction allows synthesizing samples of press...

This article aims at an experimental study carried out in laboratory on a calcite sand in order to characterize the behavior of the granular media using œdometric tests. Enormous great quantity of this type of material exists in the nature. In ad-dition, it is the most used in various industrial sectors especially in civil engineer-ing such as; the...

Fully resolved fluid–solid coupling is explored with the gradient corrected weakly compressible SPH methodology being used to simulate an incompressible Newtonian fluid as well as being used to obtain the coupling force information required to accurately represent these interactions. Gradient correction allows for the application of the Neumann bou...

The gravelly lateritic soils are commonly used for road sub-grade and sub-base course in tropical region due to their good bearing capacity. Whereas, the lack of their ore deposit along or near the corridors of the road construction implies the development of new approach for using these local materials in road construction works. That is why, this...

The main objective of this work is to develop a new geoamterial named geopolymer binder. The development of geopolymer has of global interest in terms of economic and ecologic constructions. This innovative product is obtained by activation of a metakaolin source by sodium silicate powder (Na2SiO3) and NaOH. Several samples and formulations were pr...

Numerous practical applications of the Discrete Element Method (DEM) require a flexible description of particles that can account for irregular and non-convex particle shape features. Capturing the particle non-convexity is important since it allows to model the physical interlocking when the particles are in contact. To that end, the most flexible...

Leachate is a source loaded with different types of pollutants. This juice is a source of pollution for the environment causing an alteration of the quality of surface and underground water and thus the contamination of the groundwater. Solve an environmental problem caused by the production of large quantities of leachates by Fez landfills is our...

The textile industry consumes a large quantity of dyes to color their final products. In this way, the adsorption treatment has been used to remove dyes. Therefore, Natural Tunisian Clay (NTC) collected from Djebel Abderrahmane Nabeul deposit can be applied like a good adsorbent for the dyes removal. NTC was purified and caracterized by chemical an...

The present paper treats the relationship between geotechnical parameters and the mineralogical compositions, in order to understand the behavior of the Bafang lateritic fine soils and their efficient use as road embankment materials on the other hand. Thus, the field campaigns have permitted to distinguish two facies of Bafang lateritic fine soils...

Ce travail est basé sur la formulation et l’élaboration d’un nouveau liant de type géopolymère obtenu par activation de la source aluminosilicate. L’élaboration d’un matériau modèle à base du métakaolin à un intérêt mondial en termes de construction économiquement et écologiquement rentable. Dans ce cadre de travail, plusieurs échantillons et formu...

Numerous practical applications of the Discrete Element Method (DEM) require a flexible description of particles that can account for irregular and non-convex particle shape features. Capturing the particle non-convexity is important since it allows to model the physical interlocking when the particles are in contact. To that end, the most flexible...

This research aims at studying the shear behavior of homogeneous and heterogeneous granular materials by the triaxial test. The research work is performed on glass beads both in laboratory tests and by numerical simulations in DEM. The experimental tests are firstly performed on mono-disperses beads, then expanded to heterogeneous cases like bi-dis...

This paper investigates the mineral, mechanical and thermal behaviour of clay sample from Djbel BouOmrane located in Gafsa area. The aim of this report is the valorisation of this collected clay and their application in ceramic construction, especially to produce eco-friendly and sustainable building materials in order to solve problems caused by m...

Wall roughness plays a crucial role in granular medium - rough wall interface friction. In this study, an experimental device has been designed to study the influence of boundary conditions, more specifically wall roughness, on the behavior of sheared granular medium. The study is based on use of an analog model, and consists of simulating roughnes...

This paper focuses on the development of punching device dedicated to study the failure of 2D analogue soil. In order to follow the kinematic behaviours of soil, Particle Image Velocimetry (PIV) analysis has been developed and tested in the case of the shallow foundations. The results show that the field of the soil displacement under the foundatio...

This paper focuses on the development of punching device dedicated to study the failure of 2D analogue soil. In order to follow the kinematic behaviours of soil, Particle Image Velocimetry (PIV) analysis has been developed and tested in the case of the shallow foundations. The results show that the field of the soil displacement under the foundatio...

This paper focuses on the development of punching device dedicated to study the failure of 2D analogue soil. In order to follow the kinematic behaviours of soil, Particle Image Velocimetry (PIV) analysis has been developed and tested in the case of the shallow foundations. The results show that the field of the soil displacement under the foundatio...

This paper focuses on the development of punching device dedicated to study the failure of 2D analogue soil. In order to follow the kinematic behaviours of soil, Particle Image Velocimetry (PIV) analysis has been developed and tested in the case of the shallow foundations. The results show that the field of the soil displacement under the foundatio...

This paper aims at studying the shear behavior of glass beads samples through experimental triaxial tests as regards the case of 4 mm diameter glass beads. Repeated tests are systematically carried out, together with the evaluation of the repeatability. Study of numerous experimental conditions is performed: compactness state (high/medium density),...

This paper aims at studying the shear behavior of mixtures of fine and coarse particles by classical triaxial tests. The work is performed both on experimental tests and computer simulations by discrete element method. The comparisons between experimental and simulation results on monosized and binary samples show that the DEM model can reproduce d...

Les déchets de démolition sont utilisés comme substituant du gravier dans la formulation d’un béton de granulats recyclés (BGR). Une analyse chimique du déchet issu de la démolition des murs de maçonnerie en brique a permis de valider son utilisation comme substituant des granulats pour la production du BGR. L’étude des propriétés des déchets de co...

The gravelly lateritic soils used as raw materials in road construction, have been the subject of evaluation in order to determine their spatial distribution in Bafang area (West-Cameroun). Thereby, field surveys, geotechnical properties and GIS tools by Inverse Distance Weighted (IDW) and Boolean modeling have been used to achieve the purpose. Foc...

The gravelly lateritic soils used as raw materials in road construction, have been the subject of evaluation in order to determine their spatial distribution in Bafang area (WestCameroun). Thereby, field surveys, geotechnical properties and GIS tools by Inverse Distance Weighted (IDW) and Boolean modeling have been used to achieve the purpose. Focu...

The use of the Discrete Element Method (DEM) for industrial civil engineering industrial applications is currently limited due to the computational demands when large numbers of particles are considered. The graphics processing unit (GPU) with its highly parallelized hardware architecture shows potential to enable solution of civil engineering prob...

The packing density and flat bottomed hopper discharge of non-convex polyhedral particles are investigated in a systematic experimental study. The motivation for this study is two-fold. Firstly, to establish an approach to deliver quality experimental particle packing data for non-convex polyhedral particles that can be used for characterization an...

Accurately predicting the dynamics of particulate materials is of importance to numerous scientific and industrial areas with applications ranging across particle scales from powder flow to ore crushing. Computational discrete element simulations is a viable option to aid in the understanding of particulate dynamics and design of devices such as mi...

This paper aims at studying the shear behavior of homogeneous granular materials by conventional triaxial test. The work is performed both in laboratory tests and by discrete element method simulations. Conventional triaxial tests are performed on glass beads packing, while a cylindrical rigid wall boundary condition based on lame formula and a ser...

This paper presents a DEM study of a confined granular material sheared between two parallel bumpy walls. The granular material consists of packed dry spherical particles. The bumpiness is modeled by spheres of a given diameter glued on horizontal planes. Different bumpy surfaces are modeled by varying diameter or concentration of glued spheres. Th...

This paper deals with the behavior of packed spherical particles sheared on rough surfaces. The discrete element method (DEM) is used to model the granular material. Likewise, the roughness is modeled by spherical boundary conditions. From the simulations the effect of surface roughness on the shear strength and the granular material behavior near...

In Civil Engineering, there are several examples where the tribology, in particular the friction between two bodies in motion, can be applied. This study focuses on the friction between fresh concrete and wall. This friction can be determinant for concrete pumping, pressure against formworks and quality of concrete facing. In such cases, to measure...

Understanding the dynamical behavior of particulate materials is extremely important to many industrial processes, with typical applications that range from hopper flows in agriculture to tumbling mills in the mining industry. The discrete element method (DEM) has become the defacto standard to simulate particulate materials. The DEM is a compu-tat...

This work describes a methodology based on Particle Image Velocimetry (PIV) to obtain the displacement field in the case of 2D silo discharge with analogue Schneebeli's material. The results allow showing clearly the typical flow zones as the dead zones during the discharge.

When concrete is poured into forms or during concrete pumping, a lubrication layer is formed at the interface. This layer is called “boundary layer”. In order to characterize this layer and to better understand the mechanisms leading its formation, we look to study at grain scale the interface microstructure of a granular media on a rough surface....

Lorsque le béton frais est mis en oeuvre sur chantier, une couche appelée « couche limite » se forme près de l’interface béton frais - paroi. L’objectif de notre étude est de caractériser cette couche et de mieux comprendre les mécanismes de sa formation. Pour étudier la microstructure à l’interface d’une paroi rugueuse, une étude est réalisée sur...

A new DEM model for the simulation of concrete flow is presented. Fresh concrete is described as an assembly of composite particles made of spherical hard grains representing coarse aggregates surrounded by concentric spherical layers representing mortar. Two kinds of simulations are carried out: rheological simulations performed in a Couette geome...

The Discrete Element Method (DEM) is used to investigate the compaction of ceramic powders by focusing on the role of primary particle and aggregate sizes. Hard aggregates of primary particles are represented as a collection of spherical particles bonded together by solid necks, which may break during compaction. Numerical simulations are performed...

This work describes a methodology based on Discrete Element Method (DEM) simulations to generate yield and fracture surfaces for aggregated ceramic powders. The DEM simulations, which consider the length scale of porous aggregates, are used as numerical triaxial experiments to obtain the behavior of a small volume element of powder under a given lo...

This work describes the compaction of agglomerated and aggregated ceramic powders with special emphasis on the role of primary particle size. Discrete element simulations are used to model weakly bonded agglomerates as well as strongly bonded aggregates. Crushing tests are carried out to obtain the characteristic strength of single agglomerate and...

Die compaction is a crucial stage to obtain sintered products of optimal quality from ceramic powders. Adequate green strength is required to minimize initiation of microcracks that may appear during ejection. Such microcracks would result in unacceptable defects after sintering. Here, the compaction stage of ceramic aggregated powder and the resul...

The present work describes, using Discrete Element Simulations (DEM), the consolidation of aggregated ceramic powders made of submicronic primary particles. We first investigate the crushing behavior of a single aggregate made of primary particles (or crystallites). Two types of aggregates with: a) strongly bonded (by solid necks) and b) weakly bon...

Compression mouldings of commercial SMC were performed with an instrumented industrial press under various process conditions. Results underline the influence of process parameters such as the initial SMC temperature, the axial punch velocity and the geometry of the mould on local normal stress levels. They also show negligible fibre-bundle segrega...

La simulation des procédés d'élaboration de pièces à partir de poudres passe par la prise en compte du caractère particulaire des matériaux mis en jeux. La méthode des éléments discrets (Discrete Element Method, DEM) est bien adaptée pour cette tâche. Elle permet de calculer le comportement d'un ensemble de particules à partir des forces de contact...

The modelling of processes involving powder materials needs taking into account the particulate nature of the materials involved. The Discrete Element Method (DEM) is well suited for this task. It allows the macroscopic behaviour of an assembly of particles to be calculated from the contact forces generated between each particle. Rearrangement betw...