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In this study, Smiles?? sorptivity-diffusivity numerical analysis is demonstrated to offer a comprehensive description of dead-end constant-pressure compressible cake filtration for water treatment. In addition to providing an insight on filtration performance and cake behaviour in terms of cake hydraulic permeability and compressibility in good agreement with the results derived using Ruth??s conventional cake filtration theory, the sorptivity-diffusivity model can be used to gain further information on depth-dependent local cake properties and extend our knowledge on the effect of feed suspension conditions (including solution composition, coagulant dosage and mixing) on the characteristics of the particulate assemblages (including size, structure and strength). Feed suspension conditions and primary particle properties exert significant effect on the characteristics of particles in suspensions and the resultant particulate assemblages. In the non-coagulated latex systems, an increase in ionic strength resulted in a suppression of the electric double layer of latex particles as indicated by a significant drop in the zeta potential of the feed suspension which lead to a dramatic reduction in cake hydraulic permeability. In the non-coagulated montmorillonite systems, feed suspensions with high ionic strength (1 M Na+, 50 mM Ca2+ and 50 mM Fe2+) were associated with larger suspended solids which appeared to form assemblages with nematic structures that are denser yet more permeable when compared to those with low ionic strength (0.1 M Na+, 1 mM Ca2+ and 2 mM Fe2+) which appeared to form highly ??cross-linked?? voluminous honeycomb type gel of very low permeability. Pre-coagulation of latex and montmorillonite suspensions with Al-based coagulants (alum and ACH) both resulted in formation of very large flocs which subsequently formed highly permeable solid assemblages. In the latex systems, the ratio of optimal alum to ACH dose was approximately 5:1 on a total coagulant mass basis and 1.3:1 as Al while the ratio of optimal alum to ACH dose was as high as 22:1 on a total coagulant mass basis and 6:1 as Al in the montmorillonite systems. Although both alum and ACH resulted in comparable filtration performances, the distinction in Al concentration and results of local cake properties analysis indicated the presence of different cake structures presumably due to the formation of different Al species.

Abstract DEM (Distinct Element Method) models have found numerous applications in a number of engineering disciplines, such as material handling and transport, chemical, industrial, civil, mining and mineral processing. The thesis describes developments using PFC3D (Particle Flow Code in 3D) for simulating rock fragmentation by commercial explosives. Emphasis is on the realistic simulation of explosive detonation in the blasthole as well as the flow of explosive gas from the blasthole, through the fracture network and venting to the atmosphere. Detonation can be initialized at any point along discretized blastholes and proceed up or down the hole according to the Velocity of Detonation of the explosive. Each of the explosive properties (pressure, density, extent of reaction, energy and their time derivatives) is computed according to the conservation equations and the explosive equation of state at any point along the hole. At initiation, the product calculation begins at the sonic locus with input of the detonation product provided by the non-ideal detonation code Vixen-n. The Taylor wave is then computed as a function of the blasthole expansion, which depends on the rock mass response to loading. The explosive gas is treated as a non-steady, compressible fluid and can flow through an arbitrary and evolving fracture network developed in the rock mass as a function of explosive loading. The fracture network (and flow paths) is defined by the coalescence of discrete macro-cracks. The gas has the effect of draining the blasthole and loading the fracture surface by its pressure and drag forces. Fracture intersection with free-surfaces is monitored and venting to the atmosphere is allowed. Validation of the fluid flow scheme is performed by comparing numeric results to analytic solutions for flow in shock tubes. The complete model is demonstrated by simulating stress only models, gas flow models and complete models of field-scale blasts.

In this study, Smiles?? sorptivity-diffusivity numerical analysis is demonstrated to offer a comprehensive description of dead-end constant-pressure compressible cake filtration for water treatment. In addition to providing an insight on filtration performance and cake behaviour in terms of cake hydraulic permeability and compressibility in good agreement with the results derived using Ruth??s conventional cake filtration theory, the sorptivity-diffusivity model can be used to gain further information on depth-dependent local cake properties and extend our knowledge on the effect of feed suspension conditions (including solution composition, coagulant dosage and mixing) on the characteristics of the particulate assemblages (including size, structure and strength). Feed suspension conditions and primary particle properties exert significant effect on the characteristics of particles in suspensions and the resultant particulate assemblages. In the non-coagulated latex systems, an increase in ionic strength resulted in a suppression of the electric double layer of latex particles as indicated by a significant drop in the zeta potential of the feed suspension which lead to a dramatic reduction in cake hydraulic permeability. In the non-coagulated montmorillonite systems, feed suspensions with high ionic strength (1 M Na+, 50 mM Ca2+ and 50 mM Fe2+) were associated with larger suspended solids which appeared to form assemblages with nematic structures that are denser yet more permeable when compared to those with low ionic strength (0.1 M Na+, 1 mM Ca2+ and 2 mM Fe2+) which appeared to form highly ??cross-linked?? voluminous honeycomb type gel of very low permeability. Pre-coagulation of latex and montmorillonite suspensions with Al-based coagulants (alum and ACH) both resulted in formation of very large flocs which subsequently formed highly permeable solid assemblages. In the latex systems, the ratio of optimal alum to ACH dose was approximately 5:1 on a total coagulant mass basis and 1.3:1 as Al while the ratio of optimal alum to ACH dose was as high as 22:1 on a total coagulant mass basis and 6:1 as Al in the montmorillonite systems. Although both alum and ACH resulted in comparable filtration performances, the distinction in Al concentration and results of local cake properties analysis indicated the presence of different cake structures presumably due to the formation of different Al species.

This thesis is dedicated to the derivation and the validation of a new collision model as a stabilization technique for high-order lattice Boltzmann methods (LBM). More specifically, it intends to stabilize simulations of: (1) isothermal and weakly compressible flows at high Reynolds numbers, and (2) fully compressible flows including discontinuities such as shock waves. The new collision model relies on an enhanced regularization step. The latter includes a recursive computation of nonequilibrium Hermite polynomial coefficients. These recursive formulas directly derive from the Chapman-Enskog expansion, and allow to properly filter out second- (and higher-) order nonhydrodynamic contributions in underresolved conditions. This approach is even more interesting since it is compatible with a very large number of velocity sets. This high-order LBM is first validated in the isothermal case, and for high-Reynolds number flows. The coupling with a shock-capturing technique allows to further extend its validity domain to the simulation of fully compressible flows including shockwaves. The present work ends with the linear stability analysis(LSA) of the new approach, in the isothermal case. This leads to a proper quantification of the impact induced by each discretization (velocity and numerical) on the spectral properties of the related set of equations. The LSA of the recursive regularized LBM finally confirms the drastic stability gain obtained with this new approach.

A novel approach to modelling highly compressible and reactive flows is formulated to provide high resolution closure of turbulent-scale reaction rates in the presence of very rapid transients in pressure and energy. For such flows, treatment of turbulent-micro scales are generally unattainable through traditional modelling techniques. To address this, the modelling strategy developed here is based on the Linear Eddy Model for Large Eddy Simulation (LEM-LES); a technique which has only previously been applied to weakly compressible flows. In the current formulation of the Compressible LEM-LES (CLEM-LES), special treatment of the energy balance on the model subgrid is accounted for in order for the model reaction rates to respond accordingly to strong shocks and rapid expansions, both of which may be present in reactive and supersonic flow fields. In the current study, the model implemented is verified and validated for various 1D and 2D flow configurations in a compressible Adaptive Mesh Refinement (AMR) framework. In 1D test cases, laminar and turbulent flame speeds and structure have been reproduced. Also, detonation speeds and initiation events are also captured with the model. For 2D model validation, unsteady and turbulent detonation propagation and initiation events, in a narrow channel, are simulated. Both test cases involve premixed methane-oxygen mixture at low pressures. The model is found to capture well the two-dimensional detonation cellular structure, behaviour, and initiation events that are observed in corresponding shock tube experiments. Furthermore, the effect of turbulent mixing rates is investigated though a single tuning constant. It was found that by increasing the intensity of turbulent fluctuations present, detonations exhibit larger and more irregular cell structures. Furthermore, the intensity of turbulent fluctuations is found to also have an effect on initiation events.

L’objectif de ce travail de thèse porte principalement sur la valorisation des sédiments fluviaux en couche de fondation. La caractérisation de ces sédiments nous a permis de dresser une fiche d’identité détaillée de ces sédiments incluant les propriétés physico-chimiques géotechniques et environnementales. Cette caractérisation s’avère être primordiale avant toute démarche de valorisation pour évaluer le potentiel d’utilisation des sédiments en technique routière. La déshydratation des sédiments est un prétraitement souvent indispensable. Nous avons pour cela optimisé leur déshydratation en utilisant la méthode dite de « lit de séchage ». L’influence de la déshydratation par l’ajout de polymères (adjuvant de floculation) sur les caractéristiques intrinsèques des sédiments a été explorée. Afin d’améliorer les performances mécaniques des sédiments, plusieurs traitements ont été mis aux point et expérimentés tel que les traitements aux liants hydrauliques ou l’ajout de renforts granulaires. Ces différents traitements ont été testés sur des sédiments floculés et non floculés. Pour l’optimisation de la compacité des mélanges sédiments fluviaux-ajouts granulaires (Sable Bolonnais), nous avons utilisé le modèle d’empilement compressible. Sur la base des résultats obtenus, nous avons réalisé une planche expérimentale dont l’objectif est de valider notre approche de valorisation. Un suivi mécanique et environnemental ainsi qu’une analyse des eaux de ruissèlements et de percolation ont été réalisés. Les résultats obtenus en laboratoire et in-situ nous confortent dans la perspective d’une utilisation des sédiments fluviaux en couche de fondation. / The work in this thesis focuses on the valorization of river sediments in sub-base. The characterization of these sediments allowed us to draw up their detailed identity card including physico-chemical geotechnical and environmental properties. This characterization is essential before any approach aiming to evaluate the potential use of the sediments in road engineering. The dehydration of the sediments is an essential pretreatment. Their dehydration has been optimized by using a method known as “bed of drying”. The influence of dehydration on the sediments characteristics by adding polymers (auxiliary of flocculation) was explored. In order to improve the mechanical performances of sediments, several treatments were developed and tested such as hydraulic binders or addition of granular reinforcements. These various treatments were tested on flocculated and non-flocculated sediments. To optimize the compacity of river sediments-additions (Bolonnais Sand) mixtures, we used the Compressible Packing Model. These results lead us to build an experimental board to validate our approach of valorization. A mechanical and environmental follow-up and analysis of percolation and runoff waters were carried out. The results achieved in laboratory and in-situ consolidate us to use rivers sediments in sub-base.

Experimental studies have been conducted on the topic of the interaction of compressiblevortex rings on stationary surfaces. Throughout the campaign experimentswere carried out at pressure ratios of ! 4, 8, and 12. In the classical set up of airas both the driver and driven gas, these corresponded to theoretical incident Machnumbers Ms of 1.34, 1.54, and 1.61.Experiments were conducted on vortex rings impinging on a stationary surfacelocated at three (increasing) distances (1.66, 3.33, and 5.00 inner diameters) fromthe shock tube exit and on a stationary surface at a set distance but at three anglesinclinations (75, 60, and 45deg at 3.33 inner diameters). Results of the impingementof a vortex ring on a stationary solid surface perpendicular to the flow showed asymmetrical impingement process. A boundary layer is generated over the surfacewith an associated increase in pressure. An increase in velocity due to the radialexpansion causes the pressure over the surface to decrease. This expansion leads tothe development of azimuthal wave instabilities along the core. Pressure was seen toincrease with an increase in incident Mach number value. The variation in distanceresulted in an increase in pressure with an increase in distance. This counter-intuitiveresult can be explained by the higher translational velocity at impingement, alongwith the absence of the initial radial expansion of the counter-rotating vortex rings. The variation in surface angle inclination introduced several degrees of asymmetry. One core of the vortex ring impinges first on the surface due to its closerproximity to it, while the other core is still free to propagate. This process generatesan asymmetric boundary layer over the surface, and a higher rate of stretching ofthe lower core, resulting in its dissipation. At higher incident Mach numbers, theembedded rearward facing shock is reflected and propagates perpendicularly to thesurface. At the inclination angles of 60 and 45deg, the counter-rotating vortex ringsare fully deflected upwards and orbit around the main vortex. This phenomenonresult in a significant difference in pressure distribution between the upper and lowersections of the surface.

abstract: The process of designing any real world blunt leading-edge wing is tedious andinvolves hundreds, if not thousands, of design iterations to narrow down a single design. Add in the complexities of supersonic flow and the challenge increases exponentially. One possible, and often common, pathway for this design is to jump straight into detailed volume grid computational fluid dynamics (CFD), in which the physics of supersonic flow are modeled directly but at a high computational cost and thus an incredibly long design process. Classical aerodynamics experts have published work describing a process which can be followed which might bypass the need for detailed CFD altogether. This work outlines how successfully a simple vortex lattice panel method CFDcode can be used in the design process for a Mach 1.3 cruise speed airline wing concept. Specifically, the success of the wing design is measured in its ability to operate subcritically (i.e. free of shock waves) even in a free stream flow which is faster than the speed of sound. By using a modified version of Simple Sweep Theory, design goals are described almost entirely based on defined critical pressure coefficients and critical Mach numbers. The marks of a well-designed wing are discussed in depth and how these traits will naturally lend themselves to a well-suited supersonic wing. Unfortunately, inconsistencies with the published work are revealed by detailedCFD validation runs to be extensive and large in magnitude. These inconsistencies likely have roots in several concepts related to supersonic compressible flow which are explored in detail. The conclusion is made that the theory referenced in this work by the classical aerodynamicists is incorrect and/or incomplete. The true explanation for the perplexing shock wave phenomenon observed certainly lies in some convolution of the factors discussed in this thesis. Much work can still be performed in the way of creating an empirical model for shock wave formation across a highly swept wing with blunt leading-edge airfoils. / Dissertation/Thesis / Masters Thesis Engineering 2020

This work presents an all-Mach method for two-phase inviscid flow in the presence of surface tension. A modified version of the Hartens, Lax, Leer and Contact (HLLC) approximate Riemann solver based on Garrick et al. [1] is developed and combined with the popular Volume of Fluid (VoF) method: Compressive Interface Capturing Scheme for Arbitrary Meshes (CICSAM). This novel combination yields a scheme with both HLLC shock capturing as well as accurate liquid-gas interface tracking characteristics. To ensure compatibility with VoF, the Monotone Upstream-centred Scheme for Conservation Laws (MUSCL) [2] is applied to non-conservative (primitive) variables, which yields both robustness and accuracy. Liquid-gas interface curvature is computed via both height functions [3, 4] and the convolution method [5]. This is in the interest of applicability to both cartesian and arbitrary meshes. The author emphasizes the use of VoF in the interest of surface tension modelling accuracy. The method is validated using a range of test-cases available in literature. The results show flow features that are in agreement with experimental and benchmark data. In particular, the use of the HLLC-VoF combination leads to a sharp volume fraction and energy field with improved accuracy (up to secondorder).