This research was conducted in the urban area of the municipality of Crato-CE in the Cariri. The study anger dealing with the application of a hydraulic model for runoff and free channels in a channel that winds masonry part of the urbanized area of the city center and over the years has been occurring flood events due to variable rainfall in the city. The work done included field visits possession of equipment for conducting surveys, measurements of flow, collecting images and measurement field. The information obtained from this study will be a bibliographic database to contribute to the advancement of research and provision of data for better planning and management of water resources site. / Esta pesquisa foi desenvolvida na zona urbana do municÃpio de Crato-CE na regiÃo do Cariri. O estudo tratou da aplicaÃÃo de um modelo hidrÃulico para escoamento em canais livres em um canal de concreto que percorre parte da Ãrea urbanizada do centro da cidade e que ao longo dos anos vem ocorrendo eventos de inundaÃÃo por conta das variÃveis precipitaÃÃes no municÃpio. O trabalho elaborado contou com visitas em campo de posse de equipamentos para realizaÃÃo de levantamentos topogrÃficos, aferiÃÃes de vazÃes, coleta de imagens e mensuraÃÃo de campo. As informaÃÃes obtidas nessa pesquisa servirÃo de base bibliogrÃfica para contribuir no avanÃo de pesquisas e fornecimento de dados para um melhor planejamento e gerenciamento dos recursos hÃdricos local.

Yes / The present study investigates the turbulent hydrodynamics in an open channel flow with an emergent and sparse vegetation patch placed in the middle of the channel. The dimensions of the rigid vegetation patch are 81 cm long and 24 cm wide and it is prepared by a 7× 10 array of uniform acrylic cylinders by maintaining 9 cm and 4 cm spacing between centers of two consecutive cylinders along streamwise and lateral directions respectively. From the leading edge of the patch, the observed nature of time averaged flow velocities along streamwise, lateral and vertical directions is not consistent up to half length of the patch; however the velocity profiles develop a uniform behavior after that length. In the interior of the patch, the magnitude of vertical normal stress is small in comparison to the magnitudes of streamwise and lateral normal stresses. The magnitude of Reynolds shear stress profiles decreases with increasing downstream length from the leading edge of the vegetation patch and the trend continues even in the wake region downstream of the trailing edge. The increased magnitude of turbulent kinetic energy profiles is noticed from leading edge up to a certain length inside the patch; however its value decreases with further increasing downstream distance. A new mathematical model is proposed to predict time averaged streamwise velocity inside the sparse vegetation patch and the proposed model shows good agreement with the experimental data. / Debasish Pal received financial assistance from SRIC Project of IIT Kharagpur (Project code: FVP)

No description available.

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Engineering Johannesburg, 2017 / The development of methods which are better able to predict the effect of large scale emergent roughness elements on the flow characteristics requires a better understanding of the drag coefficient under conditions likely to occur in the field. A laboratory investigation was carried out with newly developed equipment to quantify the drag force on various shaped cylinders, as well as the drag on an individual cylinder surrounded by an array of cylinders. The relationship between the drag coefficient and cylinder Reynolds number for a single circular cylinder was found to be of similar form but larger in magnitude than the established relationship for an infinitely long cylinder; the relationship departs from the infinite cylinder relationship for low cylinder Reynolds numbers. Contrary to previous research, the results for the multiple cylinder investigation did not reveal a clear relationship between the cylinder density and drag coefficient. Equations were developed and verified with existing laboratory data. These should be improved and extended by further research for field use. / MT2017

Flow-vegetation interactions are critically important for most hydraulic and sediment processes in streams and rivers and thus need to be accounted for in their management. The central goal of this project therefore was to improve the understanding of flow-vegetation interactions in patchy-vegetated river beds, which are typical in rivers. Based on laboratory experiments covering a range of selected hydraulic and patch mosaic scenarios, the hydraulic resistance mechanisms, turbulence structure, and transport mechanisms were studied. The effects of regular patch mosaic patterns (aligned and staggered) on the bulk hydraulic resistance were investigated first. For the cases in which the relative vegetation coverage BSA in respect to the total flume bed is low (BSA = 0.1), the patches mutual positions do not affect values of the friction factor. When the parameter BSA increases to intermediate values (BSA = 0.3), the spatial distribution of the vegetation patches and their interactions become crucial and lead to a significant increase in the bulk hydraulic resistance. When further increase of the vegetation cover occurs (BSA = 0.6), the effects on hydraulic resistance of patch patterns vanish. To clarify the mechanisms of the revealed patch effects on the overall hydraulic resistance, flow structure was assessed at both scales: individual patch and patch mosaic. The presence of a submerged isolated vegetation patch on the bed introduces a flow diversion which strongly alters the velocity field and turbulence parameters around the patch. Coherent structures, generated at the canopy top due to velocity shear, control the mass and momentum transfer between the layers below and above the vegetation patch. At the patch mosaic scale, a complex three-dimensional flow structure is formed around the patches which depends on the patch spacing and spatial arrangements. For the low surface area blockage factor (BSA = 0.1), the patches are sparsely distributed and the wakes are (nearly) fully developed before they are interrupted by the effects of the downstream patches. At the intermediate surface area blockage factor (BSA = 0.3), significant differences in flow structure between the aligned and staggered patches were observed. For the highest surface area blockage factor investigated (BSA = 0.6) both aligned and staggered patch mosaic configurations showed a similar behaviour. The results on the flow structure are used to provide mechanistic explanation of the observed patch mosaic effects on the bulk hydraulic resistance.

The cooling problem has become a serious subject in order to keep away from malfunctioning for a high performance and miniaturized electronic component. For instance, the monitor backlight LED must be cooled adequately. In this thesis, a natural convection cooling problem for the vertical channel with equally spaced heating blocks on one wall is studied by a numerical modeling to simulate a monitor backlight LED cooling. A control volume method is employed for the numerical modeling. The results of heat transfer coefficients and hot spots for various channel gap, LED spacing and Rayleigh number are presented. This study can provide design reference for related cooling problems.

Heat transfer and fluid flow are studied numerically for a repeating microchannel array with water as the circulating fluid. Generalized transport equations are discretized and solved in three dimensions for velocities, pressure, and temperature. The SIMPLE algorithm is used to link pressure and velocity fields, and a thermally repeated boundary condition is applied along the repeating direction to model the repeating nature of the geometry. The computational domain includes solid silicon and fluid regions. The fluid region consists of a microchannel with a hydraulic diameter of 85.58μm. Independent parameters that were varied in this study are channel aspect ratio and Reynolds number. The aspect ratios range from 0.10 to 1.0 and Reynolds number ranges from 50 to 400. A constant heat flux of 90 W/cm2 is applied to the northern face of the computational domain, which simulates thermal energy generation from an integrated circuit. A simplified model is validated against analytical fully developed flow results and a grid independence study is performed for the complete model. The numerical results for apparent friction coefficient and convective thermal resistance at the channel inlet and exit for the 0.317 aspect ratio are compared with the experimental data. The numerical results closely match the experimental data. This close matching lends credibility to this method for predicting flows and temperatures of water and the silicon substrate in microchannels. Apparent friction coefficients linearly increase with Reynolds number, which is explained by increased entry length for higher Reynolds number flows. The mean temperature of water in the microchannels also linearly increases with channel length after a short thermal entry region. Inlet and outlet thermal resistance values monotonically decrease with increasing Reynolds number and increase with increasing aspect ratio. Thermal and friction coefficient results for large aspect ratios (1 and 0.75) do not differ significantly, but results for small aspect ratios (0.1 and 0.25) notably differ from results of other aspect ratios.

This thesis presents a method for fault detection and precedent-free isolation for two types of channel flow systems, which were modeled with the finite element method. Unlike previous fault detection methods, this method requires no a priori knowledge or training pertaining to any particular fault. The basis for anomaly detection was the model of normal behavior obtained using the recently introduced Growing Structure Multiple Model System (GSMMS). Anomalous behavior is then detected as statistically significant departures of the current modeling residuals away from the modeling residuals corresponding to the normal system behavior. Distributed anomaly detection facilitated by multiple anomaly detectors monitoring various parts of the thermal-fluid system enabled localization of anomalous partitions of the system without the need to train classifiers to recognize an underlying fault. / text

The Santa Ynez Mountains of Santa Barbara County, California, have seen many major storm events during the past century. San Jose Creek, which runs out of these mountains, through the town of Goleta, and into the Pacific Ocean, has experienced several intense flood events as a result. The lower portion of the creek was diverted in 1960 to alleviate flooding through Old Town Goleta. However, flooding still occurred in the storms of 1995 and 1998. This study incorporates a hydraulic analysis component of a project aimed at re-designing this diverted portion of the channel. It presents an analysis of modifications to this reach in order to improve its capacity and reduce flooding during a 100-year event. As one of the most prominent software for hydraulic modeling for steady and unsteady state open channel flow, HEC-RAS is used to analyze multiple variations in channel geometry and combinations of lining materials. Of these modifications, the best configuration is suggested.

Heat exchangers are used in a wide variety of industrial applications. Augmentation of heat transfer can realize a reduction in heat transfer size and increase the effectiveness and efficiency of heat exchangers. Heat transfer can be enhanced with various methods where the turbulence of the fluid flow is enhanced: by adding ribs, grooves or steps to the channel wall, using helical inserts, or by adding bluff bodies in the channel flow. By using these methods, there is also an increase in pressure drop penalty and larger pumping power is required to achieve the same flow rate. Circular cylindrical bluff bodies have been found to have smaller drag coefficients than square, rectangular or triangular cylindrical bluff bodies in the channel flow. Heat transfer and pressure drop experimental tests were done for eight different circular cylindrical cross-bar arrays at 15 different Reynolds numbers, in the range of 640 to 12 500. Eight different cross-bar configurations were tested: the cylinder diameter to pitch ratios were, d/p = 0.025, d/p = 0.05, d/pi=i0.1 and d/p = 0.2, and the angle to the flow direction, was θ = 90° and θ = 45° for each of the four different diameter-to-pitch ratios. Transient CFD simulations were done using Ansys fluent for d/p = 0.05 and d/p = 0.2, for θ = 90°, at Reynolds numbers 920 and 9 700, to analyze the secondary flow structures in the wake of the cylinders, partly responsible for the heat transfer and pressure drop increase in the channel flow in comparison to the smooth channel. The k-Ω shear stress transport (SST) model was used for the simulations. A mesh dependence study was done for spatial discretization, temporal discretization and validated against the experimental setup. The pressure drop gradient was found from the test data for the hydraulically developed part of the test section to calculate the friction factors. With an increase in Reynolds number, the friction factors decreased until reaching an asymptotic value for all the cross-bar configurations. For θi=i90° the friction factors were larger than for θ = 45° for the same d/p ratio and Reynolds number. With an increase in d/p, the friction factors increased. The largest measured friction factor was f = 0.3, for configuration d/p = 0.2, θ = 90°, at Re = 640 and the smallest measured friction factor f = 0.02, for d/pi= 0.025, θ = 45°, at Re = 12 500. The friction factor ratio was then used to quantify the pressure penalty for using cylindrical cross-bars in the channel flow to enhance heat transfer. The maximum friction factor ratio, f/f0 = 16.7 occurred at Re = 9 700, for d/pi=i0.2, θ = 90° and the minimum friction factor ratio, f/f0 = 2.1, at Re = 640, for d/pi=i0.025, θ = 45°. The average Nusselt numbers were then calculated using the spatial integral average of the local Nusselt numbers. With an increase in Reynolds number, there was an increase in the average Nusselt number for all the cylindrical cross-bar configurations. For larger d/p ratios and θ = 90° cases, the average Nusselt numbers were larger than for smaller d/p ratios and θ = 45°. The largest average Nusselt number was Nuavg = 66.3, at Re = 9 700 for d/p = 0.2, θ = 90° and the smallest average Nusselt number, Nuavg = 8.7, at Re = 640 for d/p = 0.025, θ = 45°. The Nusselt number ratio could then be used to quantify the heat transfer enhancement of the cylindrical cross-bar channel to that of the smooth channel, where the largest Nusselt number ratio was, Nuavg /Nu0,avg = 3.3, for d/p = 0.2, θ = 90°, at Rei=i3 000 and the smallest Nuavg /Nu0,avg = 1.1, for d/p = 0.025, θ = 45°, at Re = 640. The CFD results concluded that the pressure drop increase and heat transfer enhancement were caused by the flow acceleration, flow separation, eddy formation, vorticity increase, and boundary layer deformation next to and behind the cylinders. The Strouhal number for the larger d/p ratios suggested that the unsteadiness in the flow is higher for the cylinder arrays with a larger diameter, increasing both the heat transfer enhancement and friction factor in comparison with the smaller diameter cylinder arrays. Finally, the thermal performance coefficients could be calculated by using the friction factor ratios and Nusselt number ratios. The thermal performance coefficient combines the effects of the heat transfer and pressure penalty increase. The thermal performance coefficients increased from Re = 640 until Rei=i3 000 after which it decreased with an increase in Reynolds number. This is because the pressure penalty starts to outweigh the heat transfer increase caused by the turbulators. The largest thermal performance coefficient was η = 1.6, for d/p = 0.025, θ = 45°, at Re = 3 000, and the lowest, η = 0.79, for d/p = 0.05, θ = 90°, at Re = 640. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2021. / Mechanical and Aeronautical Engineering / MEng (Mechanical Engineering) / Unrestricted