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The thesis deals with experimental research of mechanism of liquid breakup at twin-fluid atomizers. Four different atomizers were examined at the beginning of the research. Two of them were of standard design (Y-jet and effervescent nozzles), and the rest two atomizers were developed as a part of the thesis (so called CFT and inversed effervescent atomizers). Results show that only the inversed effervescent atomizer was capable of generating stable spray under examined conditions due to the specific breakup mechanism. This mechanism is similar to what was observed in effervescent atomizers. However, the mixing process inside the inversed effervescent atomizer is very different. The specific breakup mechanism was then defined as the main scope of the thesis. It was investigated by the high-speed imaging. The images were then processed by proper orthogonal decomposition and by fast Fourier transformation. Spray spatial development was examined using phase Doppler anemometer. The data was analyzed to describe the dynamics of the spray. A detailed description of the breakup mechanism is made from the combination of the experimental and post-processing techniques. The thesis brings new insight into the understanding of the liquid breakup mechanism and shows a potential for a further development of the inversed effervescent atomizer.

The Master´s thesis deals with the fluid layer, with types of fluidized layer and with problems which can be solve during design of new fluidized beds. The aim was find the fluidized grid, which is the best form economical and technological point of view. In this work are compared three fluidized grids. The first was part of submission. Next two additional types were then proposed by the author of thesis. Proposals grids are discussed in detail from the design phase, through the modeling and subsequent simulation part in a computer program. The results of simulation are pressure losses. Which are compared with the recommended interval values. Afterward these tested beds are put through technical and economic analysis. The result is grade which is met both requirements.

Práce se zabývá výpočty magnetických a tepelných vlastností servomotoru s permanentními magnety (motor M718 I vyráběný firmou VUES s.r.o. v Brně). Všechny uvedené výpočty jsou založené na numerických metodách konečných prvků a konečných objemů. 2D magnetická analýza motoru byla řešena s pomocí programu FEMM, zatímco pro 3D analýzu byl využit software ANSOFT. Magnetické analýzy umožnily stanovit rozložení magnetického pole v motoru a ve vzduchové mezeře. Ztráty způsobené vířivými proudy byly počítány v závislosti na rozměrech permanentních magnetů a velikosti toku magnetické indukce ve vzduchové mezeře. U 3D modelu v programu ANSOFT byly vypočítány i Joulovy ztráty. Pro daný servomotor byly navrženy dva způsoby chlazení. V prvním případě se jedná o vnitřní chladicí systém. K původnímu modelu motoru byly přidány některé modifikace (otvory v rámu motoru a radiální ventilátor na hřídeli uvnitř rámu motoru). U druhého způsobu chlazení bylo navrženo vnější chlazení. K původnímu rámu byly přidána chladicí žebra a radiální ventilátor na hřídeli vně rámu motoru. Výpočty proudění a tepelná analýza byly provedeny jak pro původní model motoru, tak i pro modifikovaný návrh (vnitřní a vnější chlazení) pomocí software ANSYS Workbench. Teplotní charakteristiky původního motoru byly měřeny různými senzory. Bylo provedeno porovnání experimentálně získaných výsledků s vypočteným teplotním modelem. Práce byla vytvořena v rámci doktorského studijního programu Elektrotechnika a komunikační technologie, obor Silnoproudá elektrotechnika a elektroenergetika. Podstatná část práce vznikla za podpory Centra výzkumu a využití obnovitelných zdrojů energie a výzkumných projektů CZ.1.05/2.1.00/01.0014 and FEKT S-11-9.

Cette thèse traite du problème de l'écoulement d'un fluide dans des interfaces étroites entre des solides en contact sous un chargement normal, ce qui est important pour de nombreuses applications en tribologie, ingénierie et géophysique. Le traitement de ce problème nécessite de prévoir un couplage entre la mécanique des fluides et celle des solides. Les contraintes liées à la présence du contact, ainsi que les caractéristiques complexes de la géométrie de surface rajoutent un niveau de complexité significatif. Dans cette thèse, un solveur monolithique par éléments finis permettant la gestion du contact frottant, des écoulements visqueux incompressibles et du transfert des efforts induits par le fluide sur le solide est développé. De plus, la possibilité que le fluide se retrouve piégé dans des cavités délimitées par des zones de contact est prise en compte par l'élaboration d'un nouvel élément dit "de fluide piégé", qui utilise une loi de comportement compressible non linéaire. Le code résultant de cette méthode comprend des algorithmes d’analyse d’image permettant de distinguer les zones de contact, d’écoulement de fluide et de fluide piégé. En outre, le code convient aux approches de couplage uni- et bidirectionnel. Le cadre développé a été appliqué dans un premier temps à l'étude d'un fluide piégé entre un solide déformable présentant une surface de contact ondulée et un plan rigide. Pour un système soumis à une charge externe croissante, nous avons examiné l'évolution de la surface de contact et du coefficient de frottement global en fonction des propriétés du fluide et du solide, ainsi que de la pente du profil de surface. Nous avons ensuite étudié l’écoulement d’un fluide entre un plan rigide et un solide déformable avec une géométrie modèle ou une surface rugueuse. Nous avons obtenu une solution analytique approchée qui gouverne le flux de fluide à travers une interface de contact ondulée, et cette dernière a été comparée à nos résultats numériques. Enfin, nous avons montré pour un intervalle de paramètres physiquement pertinents, que le couplage unidirectionnel sous-estime, par rapport à une approche bidirectionnelle, la perméabilité de l’interface ainsi que la charge externe critique nécessaire à la fermeture de l’interface. Une loi phénoménologique raffinée de perméabilité macroscopique des interfaces de contact rugueuses a été proposée. Enfin, le cadre développé a été utilisé pour calculer l'évolution de la fuite de fluide à travers une interface de contact métal sur saphir en utilisant un comportement matériau élasto-plastique et des mesures réelles de la rugosité de surface. / This thesis deals with the problem of a thin fluid flow in narrow interfaces between contacting solids subject to a normal loading, which is relevant for a range of tribological and engineering applications, as well as for geophysical sciences. The treatment of this problem requires coupling between fluid and solid mechanics, further complicated by contact constraints and potentially complex geometrical features of contacting surfaces. In this thesis a monolithic finite-element framework for handling frictional contact, thin incompressible viscous flow and transfer of fluid-induced tractions to the solid is developed. Additionally, we considered fluid entrapment in "pools" delimited by contact patches and formulated a novel trapped-fluid element using a non-linear compressible constitutive law. This computational framework makes use of image analysis algorithms to distinguish between contact, fluid flow and trapped fluid zones. The constructed framework is suitable for both one- and two-way coupling approaches. First, the developed framework was applied to a study of a fluid trapped between a deformable solid with a wavy surface and a rigid flat. We showed how the contact area and the global coefficient of friction evolve under increasing external load, depending on fluid and solid properties and on the slope of the surface profile. Next, we studied a thin fluid flow between a rigid flat and a deformable solid with a model geometry or random surface roughness. An approximate analytical solution for the fluid flow across a wavy contact interface was derived and compared with numerical results. We showed that for a range of physically relevant parameters, one-way coupling underestimates the interface permeability and the critical external load needed to seal the interface, compared to the two-way approach. A refined non-local phenomenological law for macroscopic permeability of rough contact interfaces was proposed. Finally, the developed framework was used to calculate the evolution of the fluid leakage through a metal-to-sapphire contact interface using an elasto-plastic material behaviour and real measurements of surface roughness.

Dendritic solidification has been the subject of continuous research, also because of its high importance in metal production. The challenge of predicting macroscopic material properties due to complex solidification processes is complicated by the multiple physical scales and phenomena involved. Practical modeling approaches are still subject to significant limitations due to remaining gaps in the systematic understanding of dendritic microstructure formation. The present work investigates some of these problems at the microscopic level of interfacial morphology using phase-field simulations. The employed phase-field models are implemented within a finite-element framework, allowing efficient and scalable computations on high-performance computing facilities. Particular emphasis is placed on the evolution and interaction of dendrite sidebranches in the broader context of dendrite fragmentation, varying and dynamical solidification conditions.

Proper management of multidimensional aggregates is a fundamental prerequisite for efficient OLAP. The experimental OLAP server CUBESTAR whose concepts are described, was designed exactly for that purpose. All logical query processing is based solely on a specific algebra for multidimensional data. However, a relational database system is used for the physical storage of the data. Therefore, in popular terms, CUBESTAR can be classified as a ROLAP system. In comparison to commercially available systems, CUBESTAR is superior in two aspects. First, the implemented multidimensional data model allows more adequate modeling of hierarchical dimensions, because properties which apply only to certain dimensional elements can be modeled context-sensitively. This fact is reflected by an extended star schema on the relational side. Second, CUBESTAR supports multidimensional query optimization by caching multidimensional aggregates. Since summary tables are not created in advance but as needed, hot spots can be adequately represented. The dynamic and partition-oriented caching method allows cost reductions of up to 60% with space requirements of less than 10% of the size of the fact table.

Tato diplomová práce prezentuje metodu spektrálních prvků. Tato metoda je použita k řešení stacionárního 2-D laminárního proudění Newtonovské nestlačitelné tekutiny. Proudění je popsáno stacionarní Navier-Stokesovou rovnicí. Dohromady s okrajovou pod- mínkou tvoří Navier-Stokesův problém. Na slabou formulaci této úlohy je aplikována metoda spektrálních prvků. Touto discretizací se získá soustava nelineárních rovnic. K obrdžení lineární soustavy je použita Newtonova iterační metoda. Podorobný algorit- mus tvoří jádro Navier-Stokeseva solveru, který je naprogramován v Matlabu. Na závěr jsou pomocí tohoto solveru řešeny dva příklady: proudění v kavitě a obtékání válce. Přík- lady jsou řešeny pro různé Reynoldsovy čísla. První od 1 do 1000 a druhý od 1 do 100.

A new model for simulating non-Brownian flexible fibres suspended in a Newtonian fluid has been developed. Special attention has been given to include realistic flow conditions found in the industrial papermaking process in the key features of the model; it is the intention of the author to employ the model in simulations of the forming section of the paper machine in future studies. The model considers inert fibres of various shapes and finite stiffness, interacting with each other through normal, frictional and lubrication forces, and with the surrounding fluid medium through hydrodynamic forces. Fibre-fluid interactions in the non-creeping flow regime are taken into account, and the two-way coupling between the solids and the fluid phase is included by enforcing momentum conservation between phases. The incompressible three-dimensional Navier-Stokes equations are employed to model the motion of the fluid medium. The validity of the model has been tested by comparing simulation results with experimental data from the literature. It was demonstrated that the model predicts the motion of isolated fibres in shear flow over a wide range of fibre flexibilities. It was also shown that the model predicts details of the orientation distribution of multiple straight, rigid fibres in a sheared suspension. Model predictions of the viscosity and first normal stress difference were in good agreement with experimental data found in the literature. Since the model is based solely on first-principles physics, quantitative predictions could be made without any parameter fitting. / En ny modell för simulering av rörelserna hos icke-Brownska böjliga fibrer dispergerade i en Newtonsk vätska har utvecklats. Eftersom det är författarens avsikt att modellen skall kunna tillämpas vid simulering av arkformning under de förhållanden som råder i en modern pappersmaskin, har särskilt omsorg givits till att inkludera motsvarande flödesvillkor i modellens giltighetsområde. Modellen hanterar fibrer av varierande form, massa och styvhet, som växelverkar sinsemellan via normal-, friktions- och smörjkrafter. Deras växelverkan med den omgivande vätskan sker via hydrodynamiska krafter vid finita Reynolds-tal. Den så kallade tvåvägskopplingen mellan fibrerna och vätskefasen har tagits i beaktande genom att kräva att rörelsemängden bevaras vid interaktionen mellan faserna. Vidare har Navier-Stokes ekvationer för inkompressibla vätskor använts för att beskriva mediets rörelser. Modellens giltighet har undersökts genom att jämföra resultat från simuleringar med experimentella data från litteraturen. Det har påvisats att modellen förutsäger rörelsen hos ensamma fibrer i ett skjuvflöde, för vitt skilda fiberflexibiliteter. Det visades också att modellen förutsäger detaljer hos fiberorienteringsdistributionen i suspensioner utsatta för skjuvflöde. Det kunde också konstateras att modellens förutsägelser av fibersuspensioners viskositet och första normalspänningsdifferens under skjuvning väl överensstämde med experimentella data i litteraturen. Kvantitativa förutsägelser har kunnat göras utan någon parameteranpassning, då modellen bygger uteslutande på väletablerade fysikaliska samband inom klassisk mekanik och strömningslära.

<p>The subcutaneous injection has emerged as a common approach for self-administration of biotherapeutics due to the patient comfort and cost-effectiveness. However, the available knowledge about transport and absorption of these agents after subcutaneous injection is limited. Here we aim to find drug distribution in the tissue and lymphatic uptake after subcutaneous (SC) injection. In the first part of the study, a mathematical framework to study the subcutaneous drug delivery from injection to lymphatic uptake is presented. A three-dimensional poroelastic model is exploited to find the biomechanical response of the tissue by taking into account tissue deformation during the injection. The results show that including tissue deformability noticeably changes tissue poromechanical response due to the significant dependence of interstitial pressure on tissue deformation. Moreover, the importance of the amount of lymph fluid at the injection site and injection rate on the drug uptake to lymphatic capillaries is highlighted. Finally, the variability of lymphatic uptake due to uncertainty in parameters, including tissue poromechanical and lymphatic absorption parameters, is evaluated. It is found that interstitial pressure due to injection is the major contributing factor in short-term lymphatic absorption, while the amount of lymph fluid at the site of injection determines the long-term absorption of the drug. Finally, it is shown that the lymphatic uptake results are consistent with experimental data available in the literature.</p><p>In the second part, drug transport and distribution in different tissue layers are studied. A single-layer model of the tissue as a base study was first explored. During injection, the difference between the permeability of the solvent and solute results in a higher drug concentration proportional to the inverse of the permeability ratio. Then the effects of layered tissue properties with primary layers, including epidermis, dermis, subcutaneous, and muscle layers, on tissue biomechanical response to injection and drug transport are studied. The drug distributes mainly in the SQ layer due to its lower elastic moduli. Finally, the effect of secondary tissue elements like the deep fascia layer and the network of septa fibers inside the SQ tissue is investigated. The Voronoi algorithm is exploited to create random geometry of the septa network. It is shown how drug molecules accumulate around these tissue components as observed in experimental SC injection. Next, the effect of injection rate on drug concentration is studied. Higher injection rates slightly increase the drug concentration around septa fibers. Finally, it is demonstrated that the concentration-dependent viscosity increases the concentration of biotherapeutics in the direction of septa fibers.</p><p>In the third part of this thesis, a poro-hyperelastic model of the tissue is exploited to find the biomechanical response of the tissue together with a transport model based on an advection-diffusion equation in large-deformation poro-hyperelastic Media. The process of mAbs transport to the lymphatic system is explored. This process has two major parts. First, the initial phase, where mAbs are dispersed in the tissue as a result of momentum exerted by injection. This stage last for only a few minutes after the injection. Then there is the second stage, which can take tens of hours, and as a result, monoclonal antibodies (mAbs) molecules are transported from the subcutaneous layer towards initial lymphatics in the dermis to enter the lymphatic system. In third chapter, both stages are studied. The process of plume formation, interstitial pressure, and velocity development is explored. Then the effect of the injection device, injection site, and sensitivity of long-term lymphatic uptake due to variability in permeability, diffusivity, viscosity, and binding of mAbs are investigated. Then the results are used to find an equivalent lymphatic uptake coefficient that is widely used in pharmacokinetic (PK) models to study the absorption of mAbs. We show that the injection rate is the least, and the injection site is the most important parameter in the uptake of mAbs. Injection depth and mAbs dose also significantly alter lymphatic absorption. Finally, the computational model is validated against experimental studies available in the literature.</p>