Dans cette thèse on cherche à étudier le flux péristaltique des liquides dans un canal à onde de pression déterminée aux confins. Dans la plupart des recherches de systèmes de transportation péristaltiques la variation des coordonnées de la paroi est prédéfinie pour les raisons de commodité. Cependant les parois d’organes creux (comme oesophage intestin grêle, côlon urètre, vaisseaux lymphatiques) dont le fonctionnement consiste à transmettre des produits par la voie péristaltique, sont dotées de barorécepteurs – capteurs qui perçoivent la pression dans la couche limite de fluides et servent à réguler le calibre des vaisseaux. Pour créer le modèle du comportement des systèmes biologiques pareils il nous semble plus adéquat de prédéfinir l’onde de pression aux confins des vaisseaux. Cette approche réalisée dans notre thèse permet de découvrir et décrire des effets nouveaux, inexplorés auparavant. Dans cette thèse nous étudions aussi l’influence des pulsations transversales des parois du canal sur la transmission du produit dues aux chutes de pression. Cet objectif est apparu lors de la détermination de la viscosité du liquide utilisant la méthode des canaux compressibles (squeezing flow viscometry). Des problèmes similaires sont assez répandus dans l’étude d’une variété des systèmes biologiques, en particulier, des mouvements de lubrification des articulations ou des micro-vaisseaux des muscles. Nous avons aussi étudié l’influence du son sur l’interaction d’une particule solide tombante et d’une bulle de gaz montante dans le liquide. La pertinence de ce travail est liée à l’importance de recherche des solutions possibles pour augmenter l’efficacité de flottation, méthode d’enrichissement basée sur l’accrochage des particules minérales par des bulles de gaz / The thesis studies the peristaltic flow of fluid in a channel with the specified pressure wave at the boundary. The law of wall’s coordinate variation isn’t determined a priori. It is found from the initially definite law of pressure-variation on the wall. This way is based on the fact that some hollow organs change diameter under the signals of baroreceptors (sensors that detects the pressure). We studied the effects of various parameters on flow rate and structure of flow. Besides we studied the influence of vibration on the peristaltic flow under long wave approximation. The paper also considers the influence of the wall transverse pulsation on the fluid transport under the pressure drop. This problem arises in defining the liquid viscosity by squeezing flow viscometry. The same problems occur in analyzing different biological systems, including the lubricant movement in joints or in the microvessels of working muscles. The influence of sound on the interaction of a solid particle and a gas bubble in fluid is studied as well.

Introduction : Cette thèse est issue de réflexions et d'expériences cliniques suite à un travail avec des femmes souffrant d'un trouble des conduites alimentaires (TCA) et accédant à la maternité. Dans notre recherche, parmi les différentes méthodes de Procréation Médicalement Assistée (PMA), nous avons choisi d'étudier une population ciblée : les femmes ayant recours à la pompe à la GnRH pour concevoir leurs enfants. Hypothèse principale : il existerait un grand nombre de femmes, souffrant ou ayant souffert d'un TCA, qui auraient recours à la pompe à GnRH. Hypothèse secondaire : le TCA maternel aurait des influences sur le désir d'enfant, la grossesse et les interactions précoces mère-enfant. Objectif principal : évaluer un groupe de femmes souffrant d'un TCA, enceintes après utilisation de la pompe à GnRH, à partir du 4ème mois de grossesse et jusqu'à la 8ème semaine du post-partum. Objectifs secondaires : obtenir des données scientifiques à propos des femmes souffrant d'un TCA et ayant recours à la pompe à GnRH, afin de mieux éclairer le parcours de soin de ces patientes dans les services de PMA ; obtenir des données scientifiques sur le vécu de la grossesse par les femmes TCA ; obtenir des données scientifiques sur la présence et la gravité des TCA durant la grossesse et en post-partum ; évaluer la prévalence de la dépression du postpartum chez les femmes souffrant d'un TCA. Critère d'évaluation principal : comparaison du groupe d'étude avec deux groupes témoins, l'un composé de femmes exemptes de TCA devenues enceintes par des méthodes de PMA autres que la pompe à GnRH, et l'autre composé de femmes exemptes de TCA devenues enceintes spontanément. Critères d'évaluation secondaires : évaluation de l'évolution du TCA, en pré et postnatal, par l'hétéro-questionnaire EDE ; évaluation du vécu de la grossesse par des entretiens semi-structurés ; évaluation des représentations maternelles par l'IRMAG ; évaluation de l'état psychique en pré et postnatal par l'auto-questionnaire HAD ; évaluation de l'anxiété par l'utilisation du STAI ; évaluation du risque de survenue d'une dépression du postpartum par l'auto-questionnaire EPDS. Cette étude est observationnelle et prospective : étape prénatale - 3 évaluations, entre 16 et 20 semaines d'aménorrhée (SA), entre 24 et 28 SA et entre 28 et 32 SA ; étape postnatale - 1 évaluation, à la 8ème semaine environ du postpartum. Conclusion : on constate que le TCA maternel peut être un facteur de risque en ce qui concerne la grossesse et les interactions précoces mère-bébé. L'utilisation de la pompe à GnRH par les femmes souffrant d'un TCA devrait être considéré comme un véritable enjeu de santé publique, requérant évaluation, prévention et prise en charge pluridisciplinaire de la grossesse jusqu'au post-partum. / Introduction: This thesis is the result of reflexions and clinical experiences from our work of pregnancy in women suffering from lifetime eating disorders (ED). Among different methods of assisted reprodutive technology (ART), we chose to study a special population: women seeking GnRH pulsatile administration treatment. Main hypothesis: there is an important rate of women with a lifetime ED seeking GnRH pulsatile administration treatment . Secondary hypothesis: maternal ED have influences on the desire for a child, pregnancy and early mother-child interactions. Main objective: to evaluate pregnant women with a lifetime ED after seeking GnRH pulsatile administration treatment, from the 4th month of pregnancy until the 8th week of postpartum. Secondary objectives: to obtain scientific data about women with lifetime ED seeking GnRH pulsatile administration treatment ; to better inform the multidisplinary care of these patients in the ART services ; to obtain scientific data about the experience of pregnancy in women with a lifetime ED and about the presence and severity of ED during pregnancy and postpartum ; to estimate the prevalence of postpartum depression in these women. Design: A descriptive comparative three-group design in which collected data were compared - one of women with lifetime ED who became pregnant after GnRH pulsatile administration treatment, one of women without lifetime ED who became pregnant after using other ART methods , one of women without lifetime ED who had a spontaneous pregnancy. Evaluation criteria: EDE to evaluate ED during the pre- and post-natal period ; clinical semi-structured interviews to evaluate how the pregnancy is experienced ; IRMAG to evaluate maternal representations ; HAD to evaluate anxiety and depression during the pre and postnatal period ; STAI to evaluate anxiety ; EPDS to evaluate risk of postpartum depression. This study is observational and prospective: during the prenatal period - 3 evaluations were conducted, between 16 and 20 weeks of amenorrhea (SA), between 24 and 28 SA and between 28 and 32 SA ; during the postnatal period - 1 evaluation was conducted around the 8th week. Conclusion: Eating disorders and GnRH pulsatile administration can be considered as a real public health issue, requiring strategies to address prevention, identification and multidisciplinary care for these women during pregnancy and postpartum. An eating disorder screening tool should be included in the initial intake, because these patients may be at a higher risk for negative maternal and fetal outcomes than non eating disorder patients.

Hemolysis assessment of heart pumps is necessary to be carried out before progressing to clinical trials. Blood pump hemolysis assessment standards, such as ASTM F1830 and F1841, were initially based on continuous flow pumps and included the pulsatile flow pumps later in 2019. However, a lack of guidance on the test rig design results in diverse rigs being applied in literature and companies. An aluminum-profile-based rig, which was named the old rig in this study, was created based on Gräf’s mock loop for pulsatile flow pumps in the literature. Nevertheless, this rig was without a user-friendly interface for blood-filling and de-airing, and it led to a risk of blood leakage, more effort required, and a chance of more hemolysis induced during the processes. Thus, this thesis aims to create a new rig for pulsatile flow pumps and improve its usability for blood filling and de-airing. To achieve the goals, a new rig design concept and its prototype were generated through the design thinking process. Next, user experience testings with the tasks, rig filling, de-airing, and emptying, were given to 5 users to validate if the features of the new rig could satisfy the user needs and improve the usability in terms of efficiency and user satisfaction. Lastly, two blood tests were conducted with the paired rigs, the old rig, and the new rig, based on the same pulsatile flow pump prototypes to investigate the impact of the new system layout on the hemolysis assessment. The results from the user experience testing showed that the new rig had a higher efficiency mainly based on the positive qualitative feedback of the users. The average satisfaction scores in all three tasks were higher on the new rig than on the old rig. Furthermore, the new rig did not induce more hemolysis than the old rig based on the two blood tests. Though the results were not statistically significant, the new rig could be a potential reference for a new standard of hemolysis testing on pulsatile blood pumps with user-friendly blood filling and de-airing processes. / Hemolys bedömning av hjärtpumpar är nödvändigt att utföras innan fortsättning till kliniska tester. Blodpump hemolys bedömning standarder, såsom ASTM F1830 och F1841, var initialt baserade på kontinuerliga flödespumpar, men sedan 2019 har även pulserande pumpar blivit inkluderadeDock, ingen klar vägledning av test rigg design, resulterar i att diverse riggar har använts i litteraturen och företag. En aluminiumprofilbaserad rigg, som i denna studie fick namnet den gamla riggen, skapades utifrån Gräfs mock loop för pulserande flödespumpar i litteraturen. Ändå saknade denna rigg ett användarvänligt gränssnitt för blodfyllning och avluftning, och det ledde till risk för blodläckage, mer ansträngning som krävdes och en chans att mer hemolys inducerades under processerna. Således, syftet med denna avhandling är att skapa en ny rigg för pulserade flödespumpar och förbättra användbarheten för blodfyllning och avluftning. För att uppnå målet, generades en ny rigg design koncept och dess prototyp genom designtänkande processen. Sedan, gavs följande användarupplevelse uppgifter, riggfyllning, avluftning och tömning till 5 användare för att validera om funktionerna på den nya riggen kunde uppfylla användarens behov och förbättra användbarheten gällande effektivitet och användarnöjdhet. Slutligen, genomfördes två försök med blod med de parade riggarna, gamla riggen och den nya riggen, baserat på samma pulserade flödespump prototyp för att undersöka det nya systemets layout påverkan på hemolys bedöming. Resultatet från användarupplevelse försöken visade att den nya riggen hade högre effektivitet vilket främst baserades på den kvalitativa återkopplingen från användarna. Den genomsnittliga tillfredsställelsen i alla tre uppgifter var högre med den nya riggen än med gamla riggen. Det var ingen ökning av hemolys i den nya riggen, baserat på de två blodförsöken. Trots att resultaten inte var statiskt säkerställt, så visade det sig vara en potentiell referens för en ny standard för hemolystestning på pulserade blodpumpar med användarvänliga blodfyllnings- och avluftningsprocesser.

X-ray detector windows must be thin enough to transmit sufficient low-energy x-rays, yet strong enough to withstand up to an atmosphere of differential pressure. Traditional low-energy x-ray windows consist of a support layer and pressure membrane spanning that support. Numerical modeling of several x-ray windows was used to show that both low- and high-energy x-ray transmission can be improved by adding a secondary support structure. Finite element analysis of the x-ray window models showed that the stress from a typical applied load does not exceed the ultimate strength or yield strength of the respective materials. The specific x-ray window models developed in this work may serve as a foundation for improving commercial windows, especially those geared toward low-energy transmission. For local mechanical film testing, microcantilevers were cut in suspended many-layer graphene using a focused ion beam. Multipoint force-deflection mapping with an atomic force microscope was used to record the compliance of the cantilevers. These data were used to estimate the elastic modulus of the film by fitting the compliance at multiple locations along the cantilever to a fixed-free Euler-Bernoulli beam model. This method resulted in a lower uncertainty than is possible from analyzing only a single force-deflection. The breaking strength of the film was also found by deflecting cantilevers until fracture. The average modulus and strength of the many-layer graphene films are 300 GPa and 12 GPa, respectively. The multipoint force-deflection method is well suited to analyze films that are heterogeneous in thickness or wrinkled. Bioimpedance can be measured by applying a known current to the tissue through two (current carrying) electrodes and recording the resulting voltage on two different (pickup) electrodes. Bioimpedance has been used to detect heart rate, respiration rate, blood pressure, and blood glucose. A wrist-based wearable bioimpedance device can measure heart rate by detecting the minute impedance changes caused by the modulation of blood volume in the radial artery. Using finite element analysis, I modeled how electrode position affects sensitivity to pulsatile changes. The highest sensitivity was found to occur when the pickup electrodes were centered over the artery. In this work, we used microfabricated carbon infiltrated-carbon nanotube electrodes to measure the change in contact bioimpedance for dry electrodes, and identical electrodes with a wet electrolyte, on five human subjects in the range of 1 kHz to 100 kHz. We found that the acclimated skin-electrode impedance of the dry electrodes approached that of the wet electrodes, especially for electrodes with larger areas. We also found that the acclimation time does not appear to depend on electrode area or frequency. The skin-electrode impedance after acclimation does depend on electrode area and frequency, decreasing with both. This work shows that if care is taken during the acclimation period, then dry carbon composite electrodes can be used in bioimpedance wearable applications.

Contexte: Les bénéfices associés à l’utilisation de sujets cadavériques en enseignement médical sont bien documentés et la maîtrise des dernières techniques endovasculaires est essentielle à la pratique quotidienne des chirurgiens vasculaires. Notre étude démontre la faisabilité d’élaborer un modèle cadavérique humain avec perfusion artério-veineuse antérograde pulsatile et chauffée pour une simulation endovasculaire fiable et reproductible. Méthodes: La canulation de sept sujets cadavériques conservés en solution saturée en sel a été réalisée pour permettre une perfusion centrale gauche-droite avec une solution chauffée, de l’aorte ascendante vers l’oreillette droite. Pour ce faire, nous avons utilisé des fistules artério-veineuses carotido-jugulaire et fémoro-fémorale créées chirurgicalement. Une pulsatilité de plus de 4.5 litres par minutes a été atteinte grâce à un prototype de pompe abordable conçue par des ingénieurs biomédicaux. La pression artérielle invasive et la température étaient contrôlées. Des séances de formation pour des procédures endovasculaires aortiques et des manipulations chirurgicales ouvertes ont été réalisées avec ce modèle. Résultats: Une perfusion cadavérique efficace a été possible pendant plusieurs heures, non seulement par voie artério-artérielle mais aussi avec une circulation artério-veineuse. La pression artérielle et les températures in situ ont reproduit fidèlement les fonctions vasculaires pour offrir des conditions similaires à la réalité. Ce nouveau modèle a permis de réaliser avec succès la mise en place d’une endoprothèse aortique thoracique (TEVAR), l’insertion d’un stent à l’artère sous-clavière gauche, et une simulation de la prise en charge chirurgicale ouverte d’une hémorragie sur traumatisme vasculaire. La méthode de conservation en solution saturée en sel et une pompe spécialement conçue ont amélioré la compétitivité des coûts. Conclusion: La simulation endovasculaire sur des sujets cadavériques, optimisée grâce au système de perfusion pulsatile et chauffé, peut être un complément dynamique à la formation chirurgicale et pour se familiariser avec de nouveaux instruments. Cet outil pédagogique reproductible pourrait trouver sa place dans tous les programmes d’enseignement chirurgical. / Abstract Background: The benefits of using cadaveric human subjects in surgical training are well documented and knowledge of the latest endovascular techniques is essential in the daily practice of vascular surgeons. Our study demonstrates the feasibility of developing an affordable human cadaveric model, with pulsatile and heated antegrade perfusion, for reliable and reproducible endovascular or surgical simulation. Methods: Cannulation of seven saturated-salt-solution embalmed human cadavers was undertaken to create a left-to-right central perfusion with a heated solution, from the ascending thoracic aorta to the right atrium. To that end, we used surgically created carotido-jugular and femoro-femoral arteriovenous fistulas. Pulsatile flow rate greater than 4.5 liters per minute was achieved with an affordable prototype pump designed by biomedical engineers. Invasive blood pressure and temperature were monitored. Training for endovascular thoracic aortic procedures and open vascular surgeries was performed using this model. Results: Effective cadaveric perfusion was achieved for several hours, not only with an arterio-arterial pathway but also with arteriovenous circulation. The arterial pressures and in situ temperatures accurately restored vascular functions for life-like conditions. This new model made it possible to successfully perform thoracic endovascular aortic repair (TEVAR), subclavian artery stenting, and simulation of abdominal open vascular trauma management. The saturated salt solution method and a specifically designed pump improved cost competitiveness. Conclusion: Endovascular simulation on human cadavers, optimized with the pulsatile and heated perfusion system, can be a dynamic adjunct for surgical training and familiarization with new devices. This reproducible teaching tool could be relevant in all surgery programs.

No abstract provided. / Thesis / Master of Engineering (MEngr) / Scope and contents: This thesis describes the behaviour of iron ore-water suspensions under turbulent flow conditions. This work is divided into two parts. Part I deals with the regimes of transport under steady state flow conditions in circular and horizontal ducts. The heterogeneous flow regime is extensively analyzed; a sequential discrimination of models with an oriented design of experiments have permitted the determination of the best model to correlate hydraulic gradients for these suspensions. A critical discussion on the limit deposit conditions is also included. Part II describes the behaviour of clear water under oscillatory flow conditions. The study demonstrates that the quasi-steady state hypothesis, i.e., fully developed flow assumption, applied to pulsatile turbulent flow under the conditions studied. Observations on the behaviour of iron ore-water suspensions under pulsatile flow are also included. The experiments were carried out using a new air-pulsing technique.

<p>Injectable, in-situ gelling magnetic plum pudding hydrogel composites were fabricated by entrapping superparamagnetic iron oxide nanoparticles (SPIONs) and thermosensitive N-isopropylacrylamide (NIPAM)-co–N-isopropylmethacrylamide (NIPMAM) microgels in a pNIPAM-hydrazide/carbohydrate-aldehyde hydrogel matrix. The resulting composites exhibited significant, repeatable pulsatile release of 4 kDa FITC-dextran upon exposure to an alternating magnetic field. The pulsatile release from the composites could be controlled by altering the volume phase transition temperatures of the microgel particles (with VPTTs over 37°C corresponding to improved pulsatile release) and changing the microgel content of the composite (with higher microgel content corresponding to higher pulsatile release). By changing the ratio of dextran-aldehyde (which deswells at physiological temperature) to CMC-aldehyde (which swells at physiological temperature) in the composites, bulk hydrogel swelling and thus pulsatile release could be controlled; specifically, lower CMC-aldehyde contents resulted in little to no composite swelling, improving pulsatile release. <em>In vitro</em> cytotoxicity testing demonstrated that the composite precursors exhibit little to no cytotoxicity up to a concentration of 2000 µg/mL. Together, these results suggest that this injectable hydrogel-microgel composite hydrogel may be a viable vehicle for <em>in vivo</em>, pulsatile drug delivery.<strong></strong></p> / Master of Applied Science (MASc)

<p dir="ltr">The kinetic-based lattice Boltzmann method (LBM) is a specialized computational fluid dynamics (CFD) technique that resolves intricate flow phenomena at the mesoscale level. The LBM is particularly suited for large-scale parallel computing on Graphic Processing Units (GPU) and simulating multi-phase flows. By incorporating a volume fraction parameter, LBM becomes a volumetric lattice Boltzmann method (VLBM), leading to advantages such as easy handling of complex geometries with/without movement. These capabilities render VLBM an effective tool for modeling various complex flows. In this study, we investigated the computational modeling of complex flows using VLBM, focusing particularly on pulsatile flows, the transition to turbulent flows, and pore-scale porous media flows. Furthermore, a new discrete dynamical system (DDS) is derived and validated for potential integration into large eddy simulations (LES) aimed at enhancing modeling for turbulent and pulsatile flows. Pulsatile flows are prevalent in nature, engineering, and the human body. Understanding these flows is crucial in research areas such as biomedical engineering and cardiovascular studies. However, the characteristics of oscillatory, variability in Reynolds number (Re), and shear stress bring difficulties in the numerical modeling of pulsatile flows. To analyze and understand the shear stress variability in pulsatile flows, we first developed a unique computational method using VLBM to quantify four-dimensional (4-D) wall stresses in image-based pulsatile flows. The method is validated against analytical solutions and experimental data, showing good agreement. Additionally, an application study is presented for the non-invasive quantification of 4-D hemodynamics in human carotid and vertebral arteries. Secondly, the transition to turbulent flows is studied as it plays an important role in the understanding of pulsatile flows since the flow can shift from laminar to transient and then to turbulent within a single flow cycle. We conducted direct numerical simulations (DNS) using VLBM in a three-dimensional (3-D) pipe and investigated the flow at Re ranging from 226 to 14066 in the Lagrangian description. Results demonstrate good agreement with analytical solutions for laminar flows and with open data for turbulent flows. Key observations include the disappearance of parabolic velocity profiles when Re>2300, the fluctuation of turbulent kinetic energy (TKE) between laminar and turbulent states within the range 2300</p>

The human heart has poor endogenous regeneration. If myocytes are lost due to injury, the myocardium is unable to restore its myocyte content and instead undergoes compensatory hypertrophy and remodeling. Cardiac tissue engineering aims to recreate and provide functional myocardium that replaces the injured myocardium. In this study, human engineered heart muscle (EHM) from cardiomyogenically differentiated human embryonic stem cells was generated. EHMs consisted of elongated, anisotropically organized cardiomyocyte bundles and responded “physiologically” to increasing calcium concentrations. To generate large myocardium capable of encompassing the ventricles, a novel process to systematically upscale the dimensions of engineered myocardium to a humanized Biological Ventricular Assisted Device (hBioVAD) was introduced. The hBioVADs formed a “pouch-like” myocardium at rabbit heart dimensions and were beating spontaneously. Further enhancement by biomimetic pulsatile loading generated “more mature” myocardium. Additional paracrine functionality was integrated by generating insulin-like growth factor-1 (IGF-1) secreting fibroblasts for tissue engineering applications. IGF-1 release induced higher levels of Akt phosphorylation and hypertrophy in cardiomyocytes resulting in increased force generation of EHM. Finally, feasibility of “paraBioVAD” (IGF-1 cell line and cardiomyocytes) implantation was demonstrated in a healthy rat model. Histological observations demonstrated engraftment on the heart and the presence of vascular structures. In conclusion, a humanized “paraBioVAD” technology for mechanic and paracrine heart support was developed. Future studies will assess its therapeutic utility in heart failure

The thesis deals with the flow in pipe bends and radial turbines geometries that are commonly found in an Internal Combustion Engine (ICE). The development phase of internal combustion engines relies more and more on simulations as an important complement to experiments. This is partly because of the reduction in development cost and the shortening of the development time. This is one of the reasons for the need of more accurate and predictive simulations. By using more complex computational methods the accuracy and predictive capabilities are increased. The disadvantage of using more sophisticated tools is that the computational time is increasing, making such tools less attractive for standard design purposes. Hence, one of the goals of the work has been to contribute to assess and improve the predictive capability of the simpler methods used by the industry. By comparing results from experiments, Reynolds Averaged Navier-Stokes (RANS) computations, and Large Eddy Simulations (LES) the accuracy of the different computational methods can be established. The advantages of using LES over RANS for the flows under consideration stems from the unsteadiness of the flow in the engine manifold. When such unsteadiness overlaps the natural turbulence the model lacks a rational foundation. The thesis considers the effect of the cyclic flow on the chosen numerical models. The LES calculations have proven to be able to predict the mean field and the fluctuations very well when compared to the experimental data. Also the effects of pulsatile exhaust flow on the performance of the turbine of a turbocharging system is assessed. Both steady and pulsating inlet conditions are considered for the turbine case, where the latter is a more realistic representation of the real flow situation inside the exhaust manifold and turbine. The results have been analysed using different methods: single point Fast Fourier Transforms (FFT), probe line means and statistics, area and volume based Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD). / Denna avhandling behandlar flödet i rörkrökar och radiella turbiner som vanligtvis återfinns i en förbränningsmotor. Utvecklingsfasen av förbränningsmotorer bygger mer och mer på att simuleringar är ett viktigt komplement till experiment. Detta beror delvis på minskade utvecklingskostnader men även på kortare utevklningstider. Detta är en av anledningarna till att man behöver mer exakta och prediktiva simuleringsmetoder. Genom att använda mer komplexa beräkningsmetoder så kan både nogrannheten och prediktiviteten öka. Nackdelen med att använda mer sofistikerade metoder är att beräkningstiden ökar, vilket medför att sådana verktyg är mindre attraktiva för standardiserade design ändamål. Härav, ett av målen med projektet har varit att bidra med att bedöma och förbättra de enklare metodernas prediktionsförmåga som används utav industrin. Genom att jämföra resultat från experiment, Reynolds Averaged Navier-Stokes (RANS) och Large Eddy Simulations (LES) så kan nogrannheten hos de olika simuleringsmetoderna fastställas. Fördelarna med att använda LES istället för RANS när det gäller de undersökta flödena kommer ifrån det instationära flödet i grenröret. När denna instationäritet överlappar den naturligt förekommande turbulensen så saknar modellen en rationell grund. Denna avhandling behandlar effekten av de cykliska flöderna på de valda numeriska modellerna. LES beräkningarna har bevisats kunna förutsäga medelfältet och fluktuationerna väldigt väl när man jämför med experimentell data. Effekterna som den pulserande avgasströmning har på turboladdarens turbin prestanda har också kunnat fastställas. Både konstant och pulserande inlopps randvillkor har används för turbinfallet, där det senare är ett mer realistiskt representation av den riktiga strömningsbilden innuti avgasgrenröret och turbinen. Resultaten har analyserats på flera olika sätt: snabba Fourier transformer (FFT) i enskilda punkter, medelvärden och statistik på problinjer, area och volumsbaserade metoder så som Proper Orthogonal Decomposition (POD) samt Dynamic Mode Decomposition (DMD). / <p>QC 20140919</p>