Bloodstain pattern analysis has been used in criminal investigations for more than 100 years. It provides valuable information about the events that took place prior to the formation of bloodstains at a crime scene. Forensic scientists use empirical laws to make a deduction from bloodstains, but the validity of these conclusions has been challenged in courts due to a lack of understanding of the underlying fluid mechanics. With this motivation, this thesis illustrates how mathematical modeling and numerical simulation can help gain insight into the spreading of blood droplets which eventually leads to the formation of a bloodstain. Understanding the fluid mechanics of droplet spreading and sliding has been accomplished with the help of the lubrication approximation which simplifies the Navier-Stokes equations to a more tractable form, i.e. a coupled set of non-linear partial differential equations. The resulting highly non-linear coupled set of equations is discretized using Finite-Difference. The resulting algebraic system is solved via an efficient Multigrid algorithm. These equations are modified to understand the effects of contact angle hysteresis, fluid rheology and absorptive properties of substrates on sliding dynamics. Variations in the inclination of the substrate cause the droplets to attain different advancing and receding contact angles as they slide down the incline under gravitational pull. This work explores a new way to introduce contact angle hysteresis in the numerical simulation to predict the different phases of a sliding droplet. Experiments of fluid droplet spreading/sliding on inclined surfaces have been performed to measure the terminal sliding velocity. A simplified hysteresis model has been proposed. This model automatically locates the section of the contact line which is advancing and the section which is receding which enables the application of the contact angles for the advancing and receding fronts and therefore takes into account contact angle hysteresis. A simplified analytical model is also suggested for droplets moving down the incline with near circular footprints. With the inclusion of the contact angle hysteresis, simulation results were brought in closer agreement with the experimental ones and the results from both were compared with the results from the analytical model. Blood is a shear-thinning fluid. One of the main objectives of this study is to investigate numerically the effect on the spreading and/or sliding of non-Newtonian fluid droplets on surfaces. To achieve this, the effect of rheology on the leveling of thin fluid films on horizontal solid substrates is first investigated as a preliminary investigation since this problem does not involve a contact line and is therefore more tractable. A mathematical model based on the lubrication approximation which defines non-Newtonian rheology using a power-law model is presented. Results for the leveling of sinusoidal perturbations of the fluid film highlight important differences between the leveling of shear-thinning and shear-thickening fluids. Namely, the onset of leveling occurs earlier for the shear-thinning fluid than for the shear-thickening one. However, the rate of leveling is higher for the shear-thickening fluid than the shear-thinning one. An important aspect of this part of the work is the verification of the numerical implementation using the Method of Manufactured Solutions (MMS). This leveling study also highlights differences between the leveling of two-dimensional and three-dimensional perturbations. This verified numerical formulation is then used to study the effects of rheology on the spreading/sliding of droplets. Results for the spreading of fully wetting droplets on a horizontal substrate show that, for all other quantities being equal, an increase of the flow index leads to a more rapid wetting. It also shows that, even for non-Newtonian fluids, the droplet velocity asymptotes to a constant value when sliding down an inclined substrate. This terminal velocity is strongly dependent on the rheological parameters and as it is reached, the droplets travel with a visibly constant profile. Finally, the numerical simulations revealed the formation of a tail at the rear of the droplet as it slides down the incline plane in the case of shear-thickening fluids. Finally, a more complex dynamics of fluid being absorbed in a porous substrate as it slides/spreads is considered. A mathematical model based on the lubrication approximation which defines the absorptive property of a substrate using a Darcy’s model is presented. This numerical model is verified with the help of comparison between the analytical and numerical solutions for the absorption of thin film on horizontal porous substrates. Results show that physical properties of the substrates, i.e. permeability, porosity, capillary pressure and equilibrium contact angle affect the rate of absorption of the fluid. Adding inclination to the problem, introduces the gravitational pull in the absorption dynamics. This directly shows its effects on the footprints formed inside the porous substrates. The following papers, based on sections of this thesis, have appeared or been accepted for publication: - Ahmed, G., Sellier, M., Lee, Y., Jermy, M., and Taylor, M. (2013). Modeling the spreading and sliding of power-law droplets. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 432:2–7. - Ahmed, G., Sellier, M., Lee, Y., Jermy, M., and Taylor, M. (2014). Rheological effects on the leveling dynamics of thin fluid films. Accepted for publication in the International Journal of Numerical Methods for Heat and Fluid Flow. - Ahmed, G., Sellier, M., Jermy, M., and Taylor, M. (2014). Modelling the effects of contact angle hysteresis on sliding of droplets on inclined surfaces. Submitted for peer review in The European Journal of Mechanics - B/Fluids.

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I present physical shear-box experiments investigating the relationship between geometrical properties of shear zones and mechanical properties of deformed rocks. Experimental methodology is also examined critically and new materials for analogue modelling of shear localization are presented. First, I tested experimentally whether meaningful rheological information can be deduced from finite geometrical shear zone data. The results predict characteristic geometrical responses for certain end-member materials. However, it will be difficult to constrain such responses in the field. In the second part physical controls on deformation in the shear box are analysed for Newtonian and power-law fluids and an elastoviscoplastic strain-softening material. Since models always represent simplifications of the natural problem, it is essential to understand fully the physics of a given simulation. I show that displacement boundary conditions, model geometry, and rheology control shear zone geometry. Practical applications of the shear box for modelling natural shear localization and limitations of isothermal physical models with displacement boundary conditions in general are discussed. In the third part, new data on the rheology of highly-filled silicone polymers are introduced. Since dynamic similarity must be satisfied in analogue models to permit scaled, quantitative simulations of deformation processes, the choice of suitable rock analogues is critical for physical experiments. In particular, we address the problem of designing power-law fluids to model rocks deforming by dislocation creep. We found that highly-filled polymers have complex rheologies. Hence, such materials must be used with care in analogue modelling and only for certain experimental stress-strain rate conditions. Finally, I investigated whether fault network geometry and topography of brittle strike-slip faults are influenced by the degree of compaction of the host rock. Analogue shear experiments with loose and dense sand imply that the degree of sediment compaction may be a governing factor in the evolution of fault network structure and topography along strike-slip faults in sedimentary basins. Therefore, models of strike-slip faults should consider potential volume changes of deformed rocks.

The dewatering of wastewater sludge (slurry) is a routine operation at wastewater treatment plants, and the results of dewaterability tests underpin the selection of dewatering processes. The two most commonly applied dewaterability tests for this purpose are the capillary suction time (CST) test and the specific resistance to filtration (SRF) test. The aim of this research was to develop improved methods of estimating sludge dewaterability by modifying the components and procedures used in the standard CST test, and by exploring the causes of the high variability that confounds the interpretation of the CST test results. The applications of this research were to recommend alternative methodologies that would help to improve the accuracy and precision of the standard CST test device and procedures, and ideally reduce operational and consumable costs. Multi-factorial experiments were designed to test the capillary suction times and the specific resistances to filtration of natural sludges and also of a synthetic medium which was formulated to simulate the properties of natural sludges. The applicability of altering the funnel geometry of the CST device, and the use of several alternative types of filter paper was evaluated. The applicability of incorporating stirring activity to eliminate or a least reduce sedimentation, and of adding a sealant at the bottom of the funnel, to eliminate or at least minimize unwanted filtrate leakage between the edge of the funnel and the filter paper, were studied. Experiments were performed to analyze the effects of temperature on the properties of sludges and the results of CST tests. Improved methods of estimating sludge dewaterability were developed by modifying the components and procedures used in the standard CST test, and by exploring the causes of variability in the test results. Stable synthetic sludges were successfully formulated to simulate the properties of natural sludges for experimental purposes. A rectangular funnel significantly reduced the variability and the time taken to conduct the CST test, relative to a circular funnel, particularly when testing heavy sludges. Whatman 17 chr (the most commonly used anisotropic filter paper) did not produce the most consistent CST test results in the shortest time. It is recommended that isotropic filter papers could be used, to lower the cost, reduce the test time, and improve the test precision. The addition of a sealant to the CST test apparatus also reduced the variability in the test results. No significant effects were found when a stirrer was added to the apparatus. The best line of fit to estimate filterability was defined by loge Y = β0 + β1 √x where Y = the mean CST value (s); β0 = the intercept (the predicted mean CST (s) when the distance4 between electrodes of the CST device is zero); β1 = the filterability (s/m2); X = the distance4 (m) between the electrodes of the CST device. Non-linear relationships were found between the CST test times and the temperature, associated with a complexity of effects of the temperature on sludge viscosity, filterability, settleability, desorptivity, and flocculation behaviour. It is recommended that the temperature should be recorded and controlled during the conduction of CST tests. SRF test results were predicted from the results of CST tests by the empirical model loge SRF = 46.128 – 1.346 T + 0.035 T2 + 13.760 F/TSS where SRF is the specific resistance to filtration (m/kg); T is the temperature (ºC); F is the filterability (loge s/m2) and TSS is the total suspended solids concentration (g/l).

Carbon nanotubes are known as ideal fillers for polymer systems; the main advantage of carbon nanotubes over other nano-reinforcing particles is the combination of superior strength and stiffness with large aspect ratio. Carbon nanotubes may improve the mechanical, electrical and thermal properties of polymers, but to realise their potential in polymer systems uniform dispersion, strong interfacial adhesion and alignment of nanotubes within the polymer matrix are necessary. These properties are not easy to achieve and they are key challenges in producing CNT/Polymer system. This research was carried out in an attempt to understand how the properties of CNT/Polymer composite can be optimised by manipulation of additives, compounding and postcompounding conditions. Polypropylene/Multi-Walled Carbon Nanotube (PP/MCNT) composites were prepared by conventional twin screw extrusion. Dispersants and compatibilisers were used to establish good interaction between filler and polymer. Several different extruder screw configurations were designed and the properties of PP/MCNT composite prepared by each configuration investigated. The results indicated that the addition of carbon nanotubes without additives enhanced mechanical, electrical and thermal properties of polypropylene polymer. Incorporation of compatibilisers into PP/MCNT improved the stiffness but decreased the strength of the nanocomposite, whilst addition of dispersants decreased the mechanical properties of the nanocomposite. Addition of both additives at high concentration improved electrical conductivity and induced electrical percolation in the nanocomposite. Extruder screw configuration was found to have significant effect on the electrical conductivity whilst only slightly affecting mechanical properties of the nanocomposite, possibly due to the competition between dispersion and degradation of polymer chains and possible reduction of carbon nanotube length by intensive shear during compounding. The use of screw configuration with high mixing intensity promoted the dispersion of nanotubes and favoured the conduction process in the nanocomposite. Finally in an attempt to improve dispersion and alignment of carbon nanotubes, compounded PP/MCNT composite was subjected to micromoulding, fibre spinning and biaxial stretching processes and the resultant properties investigated. Application of post-compounding process was found to have significant effect on mechanical and rheological properties of the nanocomposite. Stiffness and strength of the nanocomposites treated by post-compounding processes were found to increase by up to 160% and 300%, respectively. The reinforcement effect of carbon nanotubes in the stretched nanocomposites was found to be the greatest. Rheological analysis suggested that the application of post-compounding processes enhanced dispersion of carbon nanotubes within the nanocomposite. Overall, this finding of this research has shown that carbon nanotubes can be incorporated into polypropylene using conventional equipment to provide significant improvement in properties. By careful choices of additives, compounding and postcompounding conditions, specific properties can be further enhanced.

Le Cydia pommonella granulovirus (CPGV) est un insecticide naturel des ravageurs des pommes sensible à l’environnement extérieur (UV et dioxygène). Pour le protéger, nous avons encapsulé le CpGV dans des émulsions doubles de type eau dans huile dans eau (E/H/E). Cependant, l’utilisation des émulsions doubles requiert la maitrise de leur stabilité thermodynamique et la compréhension des mécanismes mis en jeu au cours de leur déstabilisation. C’est dans ce contexte que différents paramètres de formulation : procédé d’émulsification, type de stabilisant hydrophile, concentration en stabilisant lipophyle et en gouttelette d’eau, utilisation d’un agent anti-UV ont été testés pour étudier leur influence sur la libération du virus. Chaque formulation a fait l’objet de test d’efficacité sur les vergers et detransposition à l’échelle pilote afin de déterminer la formulation la plus efficace et pouvant être produit industriellement. / Cydia pommonella granulovirus (CpGV) is a natural insecticide pest of apples wich is sensitive to the external environment (UV and oxygen). To protect it, we have encapsulatedthe CpGV in double emulsions of water-in-oil-in-water (W / O / W). However, it’s necessary to understand the mechanisms involved in their destabilizationin order to master their thermodynamic stability. In that context, several various formulation parameters: emulsification processes, hydrophilic stabilizer type, lipophilic stabilizer concentration and water droplet, using a UV stabilizer were tested to study their influence on virus release. Each stable formulation undergoes efficiency tests in fields and pilot scale to determine the most effective formulation which could be industrially produced.

Les mortiers projetés sont formulés de manière très complexe, afin de notamment répondre aux exigences imposées par leur procédé de mise en place. La caractérisation et l’interprétation des leurs propriétés rhéologiques représentent ainsi un grand challenge, faisant appel à diverses thématiques de la matière molle : suspensions granulaires, dispersions colloïdales, solutions de polymère, mousses, etc. Nous considérons l’influence de divers paramètres de formulation, toutefois, le cœur de cette étude concerne l’influence des épaississants organiques, en particulier les éthers de cellulose (EC). Ces polysaccharides sont utilisés dans la pratique principalement pour leurs propriétés de rétention d’eau, mais ils ont également un fort impact sur la rhéologie. Nos résultats montrent que les EC augmentent considérablement la consistance du mortier, mais leur influence sur le seuil d’écoulement est plus complexe : celui-ci augmente pour les faibles dosages puis diminue jusqu’à s’annuler pour des dosages élevés. L’impact de l’EC sur la rhéologie du mortier a été relié à son influence sur les propriétés de la solution aqueuse interstitielle, en invoquant notamment ses aspects associatifs. La rhéologie est influencée par des facteurs externes (température, ajout de tensioactif) ainsi par la structure chimique du polymère. Avec la rhéologie oscillatoire, nous avons analysé l’impact de certains types d’épaississants sur l’organisation microstructurale du mortier. Nous avons établi une corrélation nette entre propriétés viscoélastiques et rétention d’eau. Plus l’épaississant augmente, plus les aspects dissipatifs augmentent et plus la rétention d’eau s’améliore. / Machinery rendering mortars are characterized by a highly complex mix-design, due to several requirements related to their placement process that need to be fulfilled. It is therefore a challenge to characterize their rheological properties. Indeed they display most of the features encountered in the field of soft matter. We consider the influence of several mix-design parameters on most of the fresh state properties of the mortars. However the main focus is the impact of organic thickening admixtures, in particular cellulose ethers (CE), on the rheological behavior. These admixtures are used for their water retention capacity, yet they have also a high impact on the rheological properties. CEs significantly increase the consistency, while their effect on the yield stress is more complex: when increasing CE dosage rate the yield stress first increases, and then decreases beyond a critical dosage rates. The impact of CE on the mortar rheological behavior is discussed in relationship to its effect on the properties of the interstitial aqueous solution. The associative feature of the CE polymer is particular referred to explain our results. Several parameters that may affect this property are considered. Small amplitude oscillatory shear rheology is used to probe mechanically the influence of CEs on the microstructure of the mortar. By comparing the effect of different thickening admixtures on the viscoelastic properties of the mortars a clear correlation between these properties and water retention is established. The more the admixture introduces viscous dissipation as compared to elasticity into the system, the more it increases its water retention capacity.

Author: Bc. Eva Kurková Title: Knee osteoarthritis: a biological response to medication class SYSADOA Problem definition: Knee osteoarthritis is a degenerative joint disease which belongs to the most common musculoskeletal diseases. The disease is associated with pain of the knee joints, which causes patients' limitations in activities of daily living. Therefore, the objective of the treatment of osteoarthritis is to reduce the pain and a progression of the disease. To achieve these aims, conservative or surgical methods are used. The conservative methods include, among others, the pharmacological treatment. Since the medicaments from the class SYSADOA are easily available we can use them during treatment. Aim of the thesis: The aim of the thesis is to determine the effect of SYSADOA medication on the 2nd and 3rd degree of the knee osteoarthritis. The effect is determined by patients' subjective evaluations and by the changes of the rheological properties of the knee joint. Method: The survey contains an anamnesis questionnaire and the clinical examination of the knee joint. The rheological properties of the knee joint are evaluated by a special device - knee rheometer that non-invasively and painlessly measures the dependence of the passive resistance of the knee joint on its bending angle. To...

Dans ce travail, nous choisissons, dans l'optique de mieux comprendre le rôle joué par les éthers de cellulose dans les mortiers monocouches, d'utiliser la rhéomètrie pour identifier les mécanismes d'action de ces molécules au sein d'une pâte de ciment. Nous développons ainsi les protocoles et l'analyse associée nous permettant, à partir de mesures macroscopiques, d'affiner notre compréhension de ces molécules à une échelle microscopique. Puis, nous extrapolons de nos résultats les conséquences d'une modification du dosage ou des paramètres moléculaires de l'éther dans le cas du mortier monocouche et de sa mise en œuvre. Dans une première partie, nous étudions l'influence de l'ajout d'éthers sur la viscosité du fluide interstitiel d'une suspension cimentaire et le rôle de ce paramètre sur la rétention d'eau. Dans une deuxième partie, nous étudions l'effet des éthers de cellulose sur le seuil d'écoulement et la déformation critique de pâtes de ciment et le rôle de ces paramètres sur la capacité d'adhésion du mortier. Dans une troisième partie, nous étudions l'effet des éthers de cellulose sur la viscosité d'une pâte de ciment et le rôle de ce paramètre sur la facilité de lissage / We choose in this work to use rheology to understand the role of cellulose ethers in render mortars and identify their mechanisms of action in a cement paste. We develop some protocols and their analysis to improve, from macroscopic measurements, our understanding of these molecules at a microscopic scale. We then extrapolate from our results the consequences of a change in amount, nature or chemical structure of the ether on the render mortar fresh properties. In a first part, we study the influence of ethers on the viscosity of a cement paste interstitial fluid and the effect of this viscosity on water retention. In a second part, we study the effect of cellulose ethers on the yield stress and critical deformation of cement pastes and the role of these rheological parameters on the properties of the render mortar. In a third part, we focus on the influence of cellulose ethers on the viscosity of cement pastes and the role of this parameter on the application easiness of the render mortar

Ce travail de thèse porte sur les liens entre les conditions opératoires du procédé de mise en œuvre par mélange à l'état fondu et la structure de nanocomposites polypropylène/argile, ainsi que sur l'influence de l'état de dispersion de l'argile sur les propriétés mécaniques des matériaux obtenus. L'étude est basée sur des essais expérimentaux. Les analyses structurales sont réalisées en s'appuyant sur la rhéologie, la diffraction de rayons X ainsi que sur des observations en microscopie électronique.Les études en mélangeur interne ont montré, d'une part, que l'augmentation de la concentration en agent compatibilisant (PP-g-MA) favorise la dispersion de l'argile à l'échelle manométrique tout en augmentant la fragilité des nanocomposites, et d'autre part, que le mélange par voie mélange maître permet d'améliorer considérablement l'état de dispersion comparativement à la voie directe. Les essais réalisés en extrusion bivis corotative ont permis de mettre en évidence l'impact de la vitesse de rotation des vis (N), du débit d'alimentation (Q) et de la température de régulation (Trég) sur l'état de dispersion. L'influence de ces trois variables peut être décrite à l'aide d'un paramètre unique : l'énergie mécanique spécifique (EMS). L'accroissement de l'EMS entraîne une augmentation du niveau d'exfoliation jusqu'à une valeur critique au-delà de laquelle les conditions opératoires ne semblent plus influencer l'état de dispersion. Une relation entre le module de Young des nanocomposites et le niveau d'exfoliation a été établie. Le logiciel LUDOVIC© nous a permis de montrer que l'EMS permet également une bonne description de la progression de l'état de dispersion le long du profil d'extrusion. Enfin, l'étude du comportement thixotrope des nanocomposites à l'état fondu a notamment permis de comprendre que le principe de superposition temps-température ne s'applique pas systématiquement aux nanocomposites étant donné leur caractère évolutif. / The present PhD work deals with the relationships between melt processing conditions and the structure of polypropylene-layered silicate nanocomposites, as well as the influence of the dispersion state on the mechanical properties of nanocomposites. This study is based on experimental results. Structural analysis are performed using rheology, X-ray diffraction and electron microscopy.Internal mixer studies revealed that the increase of compatibilizer (PP-g-MA) content simultaneously leads to enhanced nanoscale dispersion and increased brittleness of the nanocomposites. A significantly higher dispersion was stated using a masterbatch method, as opposed to direct blending method. Co-rotating twin screw extrusion experiments allowed to highlight the effect of screw rotation speed (N), feed rate (Q) and barrel temperature (TrÈg) on the degree of dispersion. The influence of these three parameters on the nanocomposites structure can be described using the specific mechanical energy (SME) as a single processing parameter. Exfoliation is clearly promoted by the increase of the SME until it reaches a critical value. Above that threshold, the degree of exfoliation levels off and improvement of the dispersion state cannot be obtained through the optimization of processing conditions anymore. A relationship between the Youngís modulus of the nanocomposites and the exfoliation level has been established. Twin screw extrusion simulation software (LUDOVIC©) was used to calculate the evolution of processing data along the screw profile. From these results, a correlation between the progression of the dispersion state along the extrusion profile and the SME was found. Eventually, rheological investigation on the thixotropic behaviour of nanocomposites enabled to emphasize that time-temperature superposition principle doesn't systematically hold true for nanocomposites because of their structure aging.