The diploma thesis contains a research part focused on turbocharger construction, engine lubrication system and turbocharger, basic physical properties of lubricating oils and hydrodynamics. The purpose of this thesis is to create analytical and CFD computational model of turbocharger lubrication system. Output pressures and the loss of specific energy are determined.

This master´s thesis solves the problem of stationary viscous flow of incompressible fluids in thin layers of fluid film lubrication in fixed pad thrust bearings. The parametric computational model of oil domain was created for investigation the distribution of pressure, velocity and thermal fields together with the determination of the basic parameters as axial force, heating up and friction loss. Subsequently this model was applied for investigation influence of uneven bearing clearance. The problem task was solved by final volume method in Ansys CFX 12.0 software.

<div> <p>The electric arc furnace (EAF) is one of the most widely-used steelmaking process recycling the scrap as the raw material. Electric arc furnace steelmaking is a material-dependent and energy-consuming process. The electricity is utilized as the main heat source to melt the scrap by the electric arc discharging from the graphite electrodes. Since the plasma arc weld has the very similar heat transfer mechanism and melting phenomenon comparing with the scrap melting in EAF process, the model development for the free-burning arc, the arc-metal heat transfer, and the metal melting will refer to the research of plasma arc weld field and start with a relatively small scale. In this study, a comprehensive computational dynamics (CFD) model was developed to predict the heat transfer from the electric arc to the metal anode, which is composed of the DC electric arc model, solidification and melting model, and the arc-metal heat transfer model. The validation of the CFD models has been conducted utilizing the experimental data and simulation results in other literature. The commercial software, ANSYS FLUENT^®, was employed with the User-Defined Function scripts and the User-Defined Scalar to model the magnetic field, comprehensive flow field, and high temperature field. Furthermore, the parametric studies for the process of the anode melted by the plasma arc were performed to investigate the effects of the arc current and the initial anode temperature on the anode melting. The results reveal that the value of the arc current has a positive correlation with the arc temperature and velocity but has negative correlation with the penetration time of the anode. Meanwhile, with the increase of anode initial temperature, the metal penetrate time will decrease.</p> </div> <br>

Contact angle behavior controls the spreading, sticking, or movement of fluid droplets on top of solid substrates, and the immiscible displacement of mixed fluids in porous media. Therefore, it influences applications such as oil recovery, CO2 geological storage, water transport in unsaturated soils, and DNAPL soil remediation techniques. The attraction forces and geometrical-molecular arrangement at the atomic scale define the strength of the interfacial tension that changes in response to changes in temperature, pressure, or the fluid composition within the system. Contact line behavior such as contact line pinning or depinning, microscale roughness, and changes in interfacial tensions influence advancing and receding contact angles. This study consists of a comprehensive database of published advancing and receding contact angles to understand the underlying mechanisms of contact line pinning and depinning and the implications of these phenomena on advancing and receding contact angles. Calcite experiments that investigate advancing and receding contact angle measurements as a function of ionic concentration complement the published literature. Critical results include: an advancing contact angle trend with calcite as a function of ionic concentration, a point of minimum contact angle hysteresis when brine concentrations are close to 0.1 M, and that contact angle behavior depends on cation type and the calcite surface anisotropy. Contact line pinning prevents flow and increases contact angle hysteresis. An analysis of the database suggests that the wide range of contact angle hysteresis of calcite and quartz with water results both from hydrogen bonds and microscale roughness at the surface which leads to pinned contact lines. The Jamin effect reduces significantly in calcite when the resultant injection brines have an ionic concentration close to 0.1 M. Thus, the pressure difference required to displace a non-wetting fluid for a wetting fluid reduces, and leads to enhanced recovery of trapped oil, gas or DNAPL.

We present a method to extract and visualize vortices that originate from bounding walls of three-dimensional time- dependent flows. These vortices can be detected using their footprint on the boundary, which consists of critical points in the wall shear stress vector field. In order to follow these critical points and detect their transformations, affected regions of the surface are parameterized. Thus, an existing singularity tracking algorithm devised for planar settings can be applied. The trajectories of the singularities are used as a basis for seeding particles. This leads to a new type of streak line visualization, in which particles are released from a moving source. These generalized streak lines visualize the particles that are ejected from the wall. We demonstrate the usefulness of our method on several transient fluid flow datasets from computational fluid dynamics simulations.

Sedimenting suspensions exist in a varity of natural phenomena and industrial applications. It is already observed in experiments that the dilute fibre suspensions experience a hydrodynamics instability under gravity at low Reynolds numbers. Initially well-mixed suspensions become inhomogeneous and anisotropic due to this instability.The main goal of this work is to understand the instability in a dilute fibre suspension by means of an Eulerian approach which is based on the Navier-Stokes equations coupled to Fokker-Planck equation for the PDF of fibres.Using a linear stability analysis, we show that inertia and hydrodynamic translational diffusion damp perturbations at long wavelengths and short wavelengths, respectively, leading to a wavenumber selection. For small, but finite Reynolds number of the fluid bulk motion, the most unstable wavenumber is a finite value which increases with Reynolds number, and where the diffusion narrows the range of unstable wavenumbers. With periodic boundary conditions, numerical simulations of the full non-linear evolution in time of a normal mode perturbation show that the induced flow may either die or saturate on a finite amplitude. The character of this long time behaviour is dictated by the wavenumber and the presence or absence of the translational and rotational diffusivities.In a simulation domain confined by vertical walls, a series of alternating structures of risers and streamers emerge continuously from the walls until they meet in the middle of the domain. For moderate times, this agrees qualitatively with experimental and theoretical results. Moreover, our simulation in a vessel of infinite height obtained an increasing wavelength evolution due to the congregation of the streamers or risers. In the end, there is constantly only one streamer left, and it drifts randomly to one side of the container until the evolution reaches a steady state. It is also found that the perturbations added to the initial conditions can induce more high density regions whose sizes and velocities are strongly linked to the initial perturbations of the number density or the flow field. In addition, the maximum number of streamers increases with Reynolds number, volume fraction and channel width. / QC 20120625

abstract: Developing countries suffer from various health challenges due to inaccessible medical diagnostic laboratories and lack of resources to establish new laboratories. One way to address these issues is to develop diagnostic systems that are suitable for the low-resource setting. In addition to this, applications requiring rapid analyses further motivates the development of portable, easy-to-use, and accurate Point of Care (POC) diagnostics. Lateral Flow Immunoassays (LFIAs) are among the most successful POC tests as they satisfy most of the ASSURED criteria. However, factors like reagent stability, reaction rates limit the performance and robustness of LFIAs. The fluid flow rate in LFIA significantly affect the factors mentioned above, and hence, it is desirable to maintain an optimal fluid velocity in porous media. The main objective of this study is to build a statistical model that enables us to determine the optimal design parameters and ambient conditions for achieving a desired fluid velocity in porous media. This study mainly focuses on the effects of relative humidity and temperature on evaporation in porous media and the impact of geometry on fluid velocity in LFIAs. A set of finite element analyses were performed, and the obtained simulation results were then experimentally verified using Whatman filter paper with different geometry under varying ambient conditions. Design of experiments was conducted to estimate the significant factors affecting the fluid flow rate. Literature suggests that liquid evaporation is one of the major factors that inhibit fluid penetration and capillary flow in lateral flow Immunoassays. The obtained results closely align with the existing literature and conclude that a desired fluid flow rate can be achieved by tuning the geometry of the porous media. The derived statistical model suggests that a dry and warm atmosphere is expected to inhibit the fluid flow rate the most and vice-versa. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2019

Indiana University-Purdue University Indianapolis (IUPUI) / Bone is one of the most common sites for breast cancer metastasis. Osteocytes compose approximately 90% of the cell population in bone matrix. Osteocytes are very sensitive to mechanical stimulation, and physical activities play an essential role in maintaining bone's health. Mechanical stimulation can alter the gene expression profile in osteocytes. However, little is known about the effects of mechanical stimulation on tumor-bone interactions. In this thesis, this question has been addressed: Does applying mechanical stimulation to osteocytes change tumor-osteocytes interactions? The hypothesis is that mechanical stimulation can change osteocytes secreting signals and contribute to higher proliferation and migration of tumor cells. In this thesis, fluid flow-driven shear stress has been used as the mechanical stimulator for osteocytes, and the interactions of tumor-osteocytes, with and without mechanical stimulation has been investigated. Monolayer cultures and 3D spheroids of breast cancer cells, including TMD and 4T1 cells were cultured in the conditioned medium (CM) isolated from MLO-A5 osteocytes, and fluid flow-treated conditioned medium (FFCM), and their migratory behavior, proliferation, and protein expression have been evaluated. The results showed that in response to MLO-A5 FFCM, tumor cells behave differently in Src expression, proliferation, and migration compared to MLO-A5 CM. As opposed to MLO-A5 CM, FFCM promoted migration, reduced proliferation, and upregulated Src expression in tumor cells. Moreover, by plasmid and siRNA transfection it has been shown that Src is upstream of Snail and their upregulation is causing epithelial-mesenchymal transition(EMT) responses in tumor cells. Furthermore, ELISA concentration assessment showed the involvement of TGF-beta in Src upregulation. An in vivo study using seventeen mice was conducted to investigate the effect of mechanical stimulation on clinical conditions. Compressive loads were applied to tibia after intratibial injection of 4T1.2 cells. The results suggested that direct mechanical stimulation of metastasized bone, might not be advantageous, and cause more damage. Furthermore, the results indicated that direct mechanical loading can make the knee joint more fragile. This research showed mechanical stimulation can cause tumor cells to behave more migratory in bone microenvironment, and demonstrated its crucial role in tumor-osteocytes interactions.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18938号 / 工博第3980号 / 新制||工||1613(附属図書館) / 31889 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 松岡 俊文, 教授 後藤 仁志, 准教授 村田 澄彦 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19681号 / 工博第4136号 / 新制||工||1638(附属図書館) / 32717 / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 西脇 眞二, 教授 稲室 隆二, 教授 松原 厚 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM