[pt] presente dissertação descreve o desenvolvimento de um equipamento destinado a determinar a condutividade hidráulica de meios porosos saturados in situ. O permeâmetro consiste em uma sonda que emprega o método da vazão constante. Após sua inserção pelo modo de cravação. Uma bomba de seringa instalada na superfície do terreno é utilizada para aplicar uma vazão constante enquanto que a carga hidráulica induzida no meio é medida através de um transdutor de pressão piezoresistivo instalado no corpo da sonda. O equipamento permite o escoamento das linhas de drenagem e de medição de carga hidráulica a partir da superfície possibilitando a saturação do meio poroso após a cravação da sonda bem como minimiza as incertezas associadas à medição de pressão. Esta última é alcançada através de um transdutor diferencial de pressão com uma faixa de trabalho de 10kPa que possibilita medições de poropressões bem próximas a zona de injeção. Esta característica permite a realização de ensaios num tempo curto e minimiza o problema de compatibilidade de fluidos decorrente do processo de injeção. / [en] This thesis describes a piece of equipment developed to determine the hydraulic conductivity of saturated porous media. The permeameter consists of a pushed in probe and employs the constant flow rate method. A syringe pump installed on the surface is used to develop a constant rate of flow whereas a piezoelectric transducer installed in the probes body measures the induced change in hydraulic head. The great innovation in this device consists on its ability of saturating all of its drainage lines allowing the media to be saturated and minimizing the errors of pressure measurements. Pressure measurement is carried out using a 10kPa differential pressure transducer that enables porepressure to be measured close to the injection zone. This characteristic enables shorter tests to be carried out and minimize problems associated to fluid compability

Student Number : 9804064R - MSc research report - School of Mechanical, Industrial and Aeronautical Engineering - Faculty of Engineering and the Built Environment / A qualitative and quantitative study of the hydraulic analogy; that is the analogy between flow with a free surface and two dimensional compressible gas flow, is described. The experimentation was done using a water table, and results are compared with Computational Fluid Dynamic (CFD) results for actual free surface flow models, and a fictitious gas model. Different test cases are considered (i) a wedge moving at steady supersonic/supercritical speeds of Froude or Mach number equal to 2.38, 3.12 and 4.31 (ii)unsteady motion of a wedge accelerating to supersonic speeds and then decelerating. Quantitative results for the experimental case are achieved by using a colour encoding slope detection technique. Qualitatively, with respect to wave angles, the fictitious gas case shows the best agreement to the experimental case, but at higher Froude/Mach numbers the free surface models also show good agreement. Quantitatively, with respect to wave location and depth profile, the free surface models show better agreement to the experimental case. For the unsteady case the resulting flow patterns are quite similar for the two cases considered, namely the experimental and free surface CFD cases.

Thesis advisor: Alfredo Urzua / Thesis advisor: John Ebel / Nine empirical equations that estimate saturated hydraulic conductivity as a func- tion of grain size in well-graded sands with gravels having large uniformity coecients (U > 50) are evaluated by comparing their accuracy when predicting observed conduc- tivities in constant head permeability tests. According to the ndings of this thesis, in decreasing order of accuracy these equations are: USBR (Vukovic and Soro, 1992; USBR, 1978), Hazen (Hazen, 1892), Slichter (Slichter, 1898), Kozeny-Carman (Carrier, 2003), Fair and Hatch (Fair and Hatch, 1933), Terzaghi (Vukovic and Soro, 1992), Beyer (Beyer, 1966), Kruger (Vukovic and Soro, 1992), and Zunker (Zunker, 1932). These re- sults are based on multiple constant head permeability tests on two samples of granular material corresponding to well-graded sands with gravels. Using the USBR equation sat- urated hydraulic conductivities for a statistical population of 874 samples of well-graded sands with gravels forming 29 loads from a heap leaching mine in northern Chile are calculated. Results indicate that, using the USBR equation, on average the hydraulic conductivity of the leaching heaps has a two standard deviation range between 0.18 and 0.15 cm/s. Permeability tests on the actual material used in the heaps provided by the mine shows that the results presented in this thesis are consistent with actual observa- tions and represent saturated conductivities in heaps up to 3 m high under a pressures of up to 62 Kpa. In future work hydraulic conductivities can be combined with water retention curves, discharge rates, irrigation rates, porosities, and consolidation so as to evaluate the relationship between copper yields and the hydraulic conductivities of the heap. / Thesis (MS) — Boston College, 2016. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Geology and Geophysics.

The difficulty with sludge settleability is considered one of the main drawbacks of sequencing batch reactors. The aim of this study therefore is to improve sludge settleability by introducing a novel, two-stage settling sequencing batch reactor (TSSBR) separated by an anoxic stage. The performance of the TSSBR was compared with that of a normal operating sequencing batch reactor (NOSBR), operating with the same cycle time. The results show a significant improvement in sludge settleability and nitrogen compound removal rates for the TSSBR over the NOSBR. The average removal efficiencies of ammonia-nitrogen (NH3-N), nitrate-nitrogen (NO3-N) and nitritr-nitrogen (NO2-N) have been improved from 76.6%, 86.4% and 87.3% respectively for the NOSBR to 89.2%, 95.2% and 96% respectively for the TSSBR. In addition, the average sludge volume index (SVI) for the NOSBR has been reduced from 42.04 ml/g to 31.17 ml/g for the TSSBR. After three months of operation, there was an overgrowth of filamentous bacteria inside the NOSBR reactor, while the morphological characteristics of the sludge inside the TSSBR reactor indicated a better and homogenous growth of filamentous bacteria. TSSBR system proves to be more efficient than NOSBR by improving the sludge settleability and enhancing nitrogen compounds’ removal efficiency, therefore, the TSSBR operating conditions including (mixed liquor suspended solids, hydraulic retention time, fill conditions, fill time, volumetric exchange rate, organic loading rate and hydraulic shock) have been optimised to obtain the optimal performance of the TSSBR system regarding the treatment efficiency and sludge settling performance. The results of optimising the TSSBR operating conditions are as follows: the optimal MLSS range was 3000 mg/l to 4000 mg/l; the optimal HRT was 6 h; unaerated feeding was better than the aerated feeding, and 15 minutes was the optimal feeding time; the optimal VER value was 20%; the optimal OLR ranges were 750 to 1000 mg/l glucose loading rate and 50 to 150 mg/l potassium nitrate loading rate. Finally, the TSSBR system was operated under the obtained optimal operating conditions. The results showed that the treatment efficiency of COD and NO3-N had been improved significantly. Although the removal efficiency of NH3-N and NO2-N did not improve, the removal efficiency of both is more than 90%, which is considered a good treatment efficiency for the TSSBR system. In addition, the settling performance of the TSSBR was significantly improved after operating the system under the optimal operating conditions.

The first recorded use of hydraulic lime in construction can be traced back to at least two thousand years ago. Hydraulic lime, produced through either adding pozzolanic materials or calcining clay containing limestone, unlike air lime, can set and harden under water, developing strength through initial hydration reaction and subsequent carbonation. After WWII Portland cement mortars had almost completely replaced lime based mortars in modern construction. However, through conservation and specialist construction the benefits of hydraulic lime are becoming increasingly recognised. To support wider usage of these mortars there is a need for systematic study on the mortar properties and structural performance of lime mortared masonry. This thesis presents findings from a research programme conducted to develop understanding of the mechanical properties of natural hydraulic lime (NHL) mortared brickwork. The work focussed on the flexural strength of NHL mortared brickwork. A variety of material and environmental factors, including lime grade and supplier, mix proportion, sand type and age, have been investigated. In addition the research has completed an in-depth study on the influence of brick absorption characteristics on bond development. The two methods of flexural wall panel and bond wrench testing to establish flexural strength have been compared. In addition to flexural strength, initial shear strength and compressive strength of brickwork has also been investigated. A greater understanding of NHL mortared brickwork performance has been developed through this work. Performance of the brickwork has been related to properties of constituent materials and environmental factors. Recommendations for design performance of materials have been provided.

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Microfiche copy available in Archives and Engineering. / Bibliography: leaf 149. / M.S.

It is well understood that the spilled oil from damaged oil tankers poses a severe threat to the marine environment. Although great efforts have been devoted to studying the oil spilling from damaged oil tankers, especially double hull tanks (DHTs), the majority is subjected to an ideal condition (e.g., fixed tanks in still water; simple damage conditions) and adopts hydrostatic theories or quasi-steady models with over-simplified assumptions on data analysis or analytical prediction. These conditions or assumptions may not stand in the complex dynamic spilling process in the real spilling accident. This study brings a step further on the knowledge of oil spilling from a damaged tank by combining experimental and numerical investigations, with a focus on the dynamic spilling process from damaged oil tankers which is either fixed or subjected to motion, which have not been systematically investigated. In the experimental investigation, the submerged oil spilling from DHTs under different accidental scenarios including grounding and collision is studied. Two new sets of laboratory tests are carried out, where the damaged tank is fixed in still water. In the first set, the axial offset between the internal and the external holes on two hulls of the grounded DHT is considered to widen the scope of damage conditions which the tanker may suffer from during grounding accidents. Although all cases in this set are subjected to the same hydrostatic conditions, completely different dynamic spilling processes are observed. In the second set, the initial water thickness inside the ballast tank of the collided DHT is considered. This aims to represent the real scenarios that the external hull is generally damaged prior to the internal hull and, therefore the ballast space is partially filled by the water flowing from the surrounding environment before the internal hull is damaged. These experiments do not only advance the state of the art of the experimental study in this field, but also provide a reference for validating the numerical models developed in this study. Based on the experimental data, the correlation analysis for the discharge through the internal hole by using quasi-steady Bernoulli’s equation is presented, contributing to the development of an improved analytical model for predicting the oil spilling from damaged oil tankers. The numerical study is carried out using a numerical model developed in OpenFOAM framework, where the VOF is applied to deal with the air-oil-water multiphase flow. This model enables the users: (1) to consider air, oil and water three phases of fluid and their interaction with solid tanker hull using dynamic mesh technologies; (2) to model turbulence associated with the oil spilling process using various available turbulent models; and (3) to investigate the effects of the compressibility of the fluid. The oil spilling from damaged DHTs is simulated and validated by the experimental data. Intensive investigations are carried out to clarify uncertainties in existing numerical modelling of the oil spilling from damaged DHTs. These include (1) the associated turbulence behaviours and selecting an appropriate approach to turbulence modelling; (2) the role of fluid compressibility during the oil spilling; and (3) the effect of tank motion on the oil spilling process. For the turbulence modelling, various approaches to model the turbulence, including the large eddy simulation (LES), direct numerical simulation (DNS) and the Reynolds average Navier-Stokes equation (RANS) with different turbulence models are attempted. It is concluded that the oil spilling from DHTs is more sensitive to the turbulence modelling than that from SHTs. For DHT cases, the effective Reynolds number (Re) considering both oil outflow and water inflow is suggested to classify the significance of the turbulence and to correspondingly select the appropriate turbulence model. The investigation on the role of the air compressibility in the oil spilling from damaged DHTs reveals that the air compressibility may be considerable in a small temporal-spatial scale (e.g., jet-jet and jet-structure impact pressure), but plays an insignificant role in the macroscopic process of the oil spilling (e.g., spilling discharge and volume). In order to approach the spilling phenomena in the more realistic environment, a systematic numerical study is carried out to investigate the effect of the periodic ship motion on the oil spilling from the damaged tank. Different tank designs (i.e., SHTs and DHTs), accidental scenarios (i.e., grounding and collision) and tank motion parameters (i.e., types, frequencies and amplitude) are considered. The result indicates that the tank motion does not only cause a periodic oscillation of the oil/water flow through the broken hole, but also induces a second long-duration stage of spilling after a quasi-hydrostatic-equilibrium condition occurs, resulting in the more significant amount of spilled oil. By using both the experimental data and numerical results produced in this research, an improved prediction model for oil spilling from damaged DHTs in still is formulated. This model considers the case-dependent hydrodynamic interaction between the oil and water jet flows inside the ballast tank and its effect on the spilling process. The result using the improved model is compared with the numerical result indicating its superiority over the existing model.

In this thesis we focus on a novel experimental exploration of fluid-driven fractures in a brittle hydrogel matrix. Fluid-driven fracturing is a procedure by which a fracture is initiated and propagates due to pressure applied by a fluid introduced inside the fracture. We describe how to construct the experimental setup utilised in this research, including how to synthesise polyacrylamide hydrogels to study the processes linked with fluid-driven fracturing. These transparent, linearly elastic and brittle gels permit fracturing at low pressures and speeds allowing accurate measurements to be obtained. The broad range of modulus and fracture energy values attainable from this medium allow the exploration of particular regimes of importance. Fracturing within these hydrogels also creates beautiful spiral patterns on the plastically deformed surfaces. We analyse these patterns and discuss their formation, while also commenting on their fractal-like nature. Initially, we study single fractures that are driven by an incompressible Newtonian fluid, injected at a constant rate into an elastic matrix. The injected fluid creates a radial fracture that propagates along a plane. We investigate this type of fracture theoretically and then verify the scaling predictions experimentally. We examine the rate of radial crack growth, fracture aperture, shape of the crack tip and internal fluid flow field. We exhibit the existence of two distinct fracturing regimes, and the transition between these, in which propagation is either dominated by viscous flow within the fracture or the material toughness. Particle image velocimetry measurements also strikingly show that the flow in the fracture can alter from an expected radial symmetry to circulation cells, dependent on the regime of propagation. We then expand our research to the problem of two coplanar fluid-driven radial fractures. This was chosen to focus on the physical mechanisms that are key to fracture network formation, related to many geophysical and industrial practices. Initially, the two fractures propagate independently of each other. At a critical separation they begin to interact, with non-uniform growth occurring along the fracture edges due to the evolving stress state in the gel matrix. When the radial extents of the fractures become sufficiently large, they coalesce and form a bridge between them. Following initial contact, a large increase in flow is seen into the newly created bridge and most of the growth is localised along this, perpendicular to the line connecting the injection sources. From experimental measurements, we observe a universal dynamic behaviour for the growth of this bridge. We model this universal behaviour theoretically and construct scalings related to the growth after coalescence, which again identifies both a viscous and toughness regime. The toughness regime is verified experimentally for the bridge growth and the universal shape of the thickness profile along the bridge. The coalesced fractures then transition into a single fracture at late times. Finally, we discuss a number of other interesting scenarios that may occur such as, non-coalescing fractures, asymmetric coalescence and ridge formation.

The UK is facing an energy crisis due to the closure of old nuclear power plants which will not be replaced until Generation III nuclear reactors are built. Coal is a realistic option to fill the gap, although there is a need to use cleaner and efficient technologies as a means to comply with global environmental regulations. Supercritical coal-fired power is a viable clean coal technology; however the UK National Grid Code is built around conventional power plants, and thus compliance is uncertain. Modelling the thermal behaviour of the supercritical boiler water cycle using computational fluid dynamics is a practical method to approach compliance. The CFD models developed with the software Comsol Multiphysics were validated and verified using experimental and numerical data, respectively. Subsequently, a test-element representing one pipe from the water wall was scaled-down to match computational requirements, and tested at two different thermal boundary conditions. A strong, forcedconvective flow was revealed, with buoyancy effects at the inlet and a considerable influence of thermal acceleration. The sharp changes of the thermo-physical properties were the most influential hydrothermal factor. Heat transfer coefficient peaked near the pipe inlet, and the outlet section showed mild hydro-thermal performance, impaired by the acceleration effects.

The measurement of water in soil on a potential, gravimetric or volumetric basis is considered, with studies concentrating on the measurement of water by dielectric and neutron moderation methods. The ability of the time-domain reflectometry technique to measure water content simultaneously at different spatial locations is an important advantage of the technique. The reported apparent dielectric by the TRASE� time-domain reflectometer and Pyelab time-domain reflectometry systems is sensitive to change in extension cable length. In some soil, e.g. a commercial sand, the response to increasing extension length of extension cable is linear. For other soil a linear response occurs for certain lengths of cable at different moisture contents. A single model accounting for clay content, extension cable length, time-domain reflectometry system, probe type and inherent moisture conditions explained 62.2 % of variation from the control (0 m extension) cable. The extension cable causes a decrease in the returning electromagnetic-wave energy; leading to a decline in the slope used in automatic end-point determination. Calibration for each probe installation when the soil is saturated, and at small water contents is recommended. The ability of time-domain reflectometry, frequency-domain and neutron moderation techniques in measuring soil water content in a Brown Chromosol is examined. An in situ calibration, across a limited range of water contents, for the neutron moderation method is more sensitive to changing soil water content than the factory supplied 'universal' calibration. Comparison of the EnviroSCAN� frequency-domain system and the NMM count ratio indicates the frequency-domain technique is more sensitive to change in soil water conditions. The EnviroSCAN� system is well suited to continuous profile-based measurement of soil water content. Results with the time-domain reflectometry technique were disappointing, indicating the limited applicability of time-domain reflectometry in profile based soil water content measurement in heavy-textured soil, or soil with a large electrical conductivity. The method of auguring to a known depth and placement of the time-domain reflectometry probe into undisturbed soil is not recommended. A time-domain reflectometry system is adapted for in situ measurement of water in an iron ore stockpile. The laboratory calibration for water content of the processed iron ore compares favourably to a field calibration. In the field study, the 28 m extension cable used to connect the probes to the time-domain reflectometry affected the end-point determination of the time-domain reflectometry system. To account for this, 0.197 should be subtracted from the reported apparent dielectric before calculation of volumetric moisture content.