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Bernoulli's equation is a famous, elegant fluid mechanics relation that, in its most popular version, relates pressure, velocity, and elevation changes along each streamline in a steady barotropic inviscid flow. Despite its simplicity and restrictive assumptions, this equation is a powerful and effective analysis tool in a variety of real-flow situations. However, the Bernoulli equation is unfortunately not Galilean-invariant, i.e., it does not satisfy the desirable property of remaining unchanged under a Galilean transformation between two inertial reference frames reciprocally moving with constant velocity. In a previous paper, the author presented a Galilean-invariant formulation of the Bernoulli equation, in which a new term is introduced in the definition of the Bernoulli constant. In the present technical note, this Galilean-invariant form of the Bernoulli relation is extended to (1) unsteady flow, (2) compressible flow, and (3) a noninertial frame of reference accelerating with constant rectilinear acceleration. Similar extensions are consolidated for the classic Bernoulli equation and treated in fundamental fluid mechanics textbooks. The use of the updated Galilean-invariant Bernoulli equation in these less-restrictive contexts is illustrated with typical engineering application examples. The results demonstrate that the extended version of the Bernoulli principle can also be applied along the same flow lines in a reference frame moving with constant velocity relative to another reference frame in which the conventional Bernoulli equation is valid, provided that the Bernoulli constant includes a suitable additional term. [ABSTRACT FROM AUTHOR]

The permeability evolution of lining fracture is of great significance for the safety evaluation of tunnel engineering in service. To date, there are few reports on the evolution in concrete fracture permeability when arbitrary seepage differential pressures are applied under the coupled hydraulic–mechanical processes. In this work, long-term water flow-through experiments on concrete single fractures are conducted to examine the permeability evolution during simulating the fractured lining concrete in service. Five seepage differential pressures from 0 to 350 kPa were experimentally designed, and it was found that the permeability of the fracture slightly increases by 13% at 0 kPa and decreases by 31%–77% at 70–350 kPa. The mineral dissolution of fracture surfaces during the flow-through experiments was analyzed using X-ray diffraction, X-ray fluorescence, scanning electron microscopy with energy-dispersive spectroscopy, and inductively coupled plasma mass spectrometry. Additionally, the distribution of water flow pressure within the fractures was investigated using computational fluid dynamics, and the potential occurrence of hydrodynamic impact was proposed. These studies reveal the evolution mechanism of the permeability of concrete fractures under the coupled processes, which provides an important help to the long-term safety evaluation of tunnel engineering. [ABSTRACT FROM AUTHOR]

This paper presents the results of experimental measurements and numerical simulations on the hydromechanics of trapezoidal asymmetric piano key weirs and compares the performance of piano key weirs and labyrinth weirs with the same crest lengths and layouts. The results show that gradually increasing the sidewall angle from 0° to 6° for labyrinth weirs continuously increases the discharge capacity of the weir. In contrast, for piano key weirs, increasing the sidewall angle from 0° to 3° significantly increases the efficiency of the weir at low to medium heads, but further increasing the sidewall angle does not significantly change the efficiency of the hydraulically optimal asymmetric piano key weir. The high angle of the lateral spilling jet to the outlet keys, along the downstream half of the side crests and the widening of the outlet keys increase the discharge efficiency of the trapezoidal piano-key weir with 3° of sidewall angle and 4 unit keys, compared to the identical weir with 6° of sidewall angle. Despite the wider outlet keys at the downstream of the trapezoidal piano key weir with 6° of sidewall angle, the narrower width of the inlet key, results in a higher streamwise inertia and thus the lower discharge at the outlet keys. Discretization of the discharge along the crest of the tested weirs confirms these results. In this research, the discharge capacity of trapezoidal piano key and labyrinth weirs were examined under various conditions and their performance was compared. The authors suggest an optimal ratio of weir height to unit width for rectangular piano key weirs, which increases the discharge coefficient by 6%. This finding can be applied to new dam projects to design cost-effective and highly efficient weirs. The study also showed that increasing the sidewall angle from 0° to 6° in trapezoidal labyrinth weirs improves the discharge coefficient by an average of 10.3%. However, in trapezoidal piano key weirs, increasing the sidewall angle from 0° to 3° has a significant impact on discharge coefficient, but further increase reverses the trend. Overall, piano key weirs perform better than their labyrinth counterparts. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to calculate, analyze, and visualize fluid (liquids, gases, and dissolved gases) flows. This document provides general introductions to best practices for CFD modeling in water infrastructure for practitioners, particularly those new to CFD modeling, which is becoming a widely used tool in the design and retrofitting of water, wastewater, and stormwater infrastructure. The method serves as an alternative, or complement, to physical modeling. In recent years, CFD has often been used in evaluating and troubleshooting existing water systems as well as improving future designs. As with the applications in other fields, the popularity of CFD in the water industry has been propelled by a multitude of factors including, but not limited to, the maturity achieved by CFD techniques, the development of stable and reliable numerical schemes, and the ever-improving computer-aided design (CAD) and meshing technologies for real-world complex geometries. This has been accompanied by many commercial and open-source CFD packages that can be run on increasingly more powerful computing hardware. Despite the visible progress in the application of CFD in water infrastructure projects achieved to date, there are still many challenges that hinder the widespread use of CFD techniques in water treatment design. Perhaps more important is that many of these challenges may result in misuse of the tool with dire consequences. It is imperative that CFD practitioners appropriately apply this tool without overpromising capability or accuracy and that reviewers of CFD model results know what to look for in ensuring proper methods have been applied and that results are representative of reality. [ABSTRACT FROM AUTHOR]

Y-type screen filters are widely used in microirrigation systems. Their good hydraulic performance and working life are the premise to ensure the normal and stable operation of microirrigation systems. In addition to the particle impurities in the fluid affecting the performance of the filter, the energy loss of the vortex in the flow field is also an important factor. This study explored the flow field, vortex characteristics, and wear of a Y-type screen filter under various operating conditions and design parameters. In particular, the fluid mechanics discrete-element method was used to numerically simulate the flow characteristics and wear characteristics of five Y-type screen filter inlet velocities (0.5, 0.75, 1, 1.25, and 1.5 m/s) and five Y-junction angles (35°, 40°, 45°, 50°, and 55°) using computational fluid dynamics. The numerical simulation results were experimentally verified. With increased inlet velocity, the strong vortex extended from the filter screen to the outlet pipe. At a maximum velocity of 1.5 m/s , the vorticity degree rose by 51.49% compared with that at a minimum velocity of 0.5 m/s , and the helicity distribution slightly changed. With the increased angle of the Y-section, the vorticity in the filter also increased. The increase of the Y-junction angle from a minimum value of 35° to a maximum of 55° angle resulted in a vorticity degree rise by only 10.64%. The positive vortex area of the outlet pipe decreased with the filter angle. The Q -criterion vortex identification method revealed that high-intensity vortices were mainly distributed on the mesh of the filter screen. Through numerical simulation prediction and experimental verification by wear tests, it was found that the parts with the largest wear depth were the outlet side filter screen and shell cover area, and the wear depth increased with the flow rate. At 2 s, the wear depth at the maximum flow rate significantly exceeded that at the minimum one. After a certain period of time, the wear depth of the Y-type screen filter increased with the Y-junction angle. In practical applications, the filter with an angle of 35° was selected for operating at low flow rates below 1 m/s. Hence, its internal flow field was more moderate, and its hydraulic performance improved, reducing the filter screen wear and prolonging its service life. [ABSTRACT FROM AUTHOR]

First, the writers thank the discussers for their interest in their article and for providing further opportunity to elucidate two fundamental aspects perturbing the contribution of the Froude number (F) in assessing flow resistance in movable-bed rivers. 2 compares calculated HT ht and predicted HT ht . If HT ht , the flow is supercritical, and if HT ht , the flow is subcritical. As, HT ht does not depend only on HT ht and HT ht , these two input parameters in model development cannot be reliable. [Extracted from the article]

The research reported herein makes use of finite-volume simulations of morphing continuum theory (MCT) to reproduce critical relations of thin-airfoil theory for the simple configuration of a flat plate for supersonic and subsonic flows. With a small mesh size of N=5,600 elements, simulations confirm that inviscid flows simulated by MCT match analytic relations for lift and pressure coefficients derived from classical fluid mechanics, a result confirmed by the inviscid MCT equations. Initial success of MCTHyperFOAM version 1.0 for the flat plate indicates that the solver can be extended to more complex aerodynamic flows. [ABSTRACT FROM AUTHOR]

Early in their career, engineering students sometimes have difficulty linking academic concepts between courses and the interests that led to their enrollment. We present a design "interlude" event that is intended to improve experiential inductive learning and the vertical and horizontal integration of engineering courses. In this exercise, second year engineering students design, build, and test a scaled model of an earthen dam. The method integrates content from technical courses in which they are currently enrolled, such as statistics and fluid mechanics, and previews future courses in their curriculum, such as soil mechanics, hydrology, and hydraulics. Students consult with a range of experts, mock stakeholders, and mock protestors. Projects are evaluated for social/environmental impacts, technical design, cost, and performance, including stability, power generation, and spillway overflow. Student feedback was positive and highlights the intended benefits for the students, including interaction with industry partners, team building for the students, hands-on learning, and a better understanding of the impact of engineering projects. [ABSTRACT FROM AUTHOR]

Assessing the hydromechanical behavior of collapsible soils is always a challenging topic in an unsaturated soil mechanics context. Although numerous efforts have been made thus far to establish frameworks for explaining the stress-strain behavior of collapsible soils, many of them are developed based on the results from conventional tests without controlling or measuring the unsaturated state variables. Furthermore, modeling the hydromechanical behavior of chemical-stabilized collapsible soils has been rarely studied. To establish a constitutive model for predicting the behavior of a lime-stabilized collapsible soil, the results obtained from filter paper and unsaturated odometer tests on a lime-treated loessial soil (which are presented in a companion paper) have been analyzed by considering the effective stress approach for unsaturated soils. An empirical model for explaining the load-collapse behavior of lime-stabilized tested soil is presented. Moreover, by implementing the disturbed state concept (DSC) method, a coupled semiempirical hydromechanical model is developed to predict the disturbance level and calculate the soil strain due to application of the vertical stress in Ko condition. Both presented models in this research are introduced as functions of two important governing state and material variables, namely matric suction and lime content. Results show excellent conformance between the laboratory test results and model predictions. [ABSTRACT FROM AUTHOR]

Laminar radial flow between two parallel disks is a fundamental nonlinear fluid mechanics problem described by the Navier- Stokes (NS) equation, but is unsolved because (1) an exact solution is not found even with extensive references, and (2) it is unclear why radial flow remains laminar at high Reynolds numbers. This paper first presents exact velocity distribution solutions for developed radial inflows and outflows, proving that both flows are described by brief Jacobi elliptic sine-squared functions but with different characteristics. For inflow, a stable velocity distribution forms; for outflow, the velocity distribution may have an inflection point inducing flow instability or separation. Both velocity distributions become the classic parabolic law at low Reynolds numbers, but uniform (similar to turbulent velocity distributions) at high Reynolds numbers. Furthermore, both pressure and boundary shear stress follow an inverse-square law, but the friction factor is invariant. These results are instructive for studying nonuniform open-channel flow for which nonlinear inertia is of importance. [ABSTRACT FROM AUTHOR]

This study presents a hydromechanical model, finite-discrete element method with fluid flow in three dimensions (FDEMflow3D), that can simulate three-dimensional hydraulic fracturing of jointed rock mass with complex fracture networks. By taking full advantage of a unique topological connection between joint elements and solid elements in three-dimensional combined finite-discrete element method (FEMDEM) together with the cubic law, the authors built a three-dimensional fluid flow model. In addition, a connectivity search algorithm for arbitrarily complex three-dimensional fracture networks is proposed, which can be used to search the connectivity of arbitrarily complex three-dimensional fracture networks. Combining the connectivity search algorithm and the mechanical calculations of threedimensional FEMDEM, the authors built the three-dimensional hydromechanical coupling model FDEM-flow3D, which directly implements hydromechanical coupling and can simulate fluid-driven fracturing in rock with arbitrarily complex three-dimensional fracture networks. Finally, the authors give five examples to validate FDEM-flow3D in dealing with the problems of steady flow, unsteady flow, hydromechanical coupling, connectivity search of discrete fracture networks, and hydraulic fracturing. The simulation results agree well with the theoretical or experimental results. The model provides a powerful tool for simulation of hydraulic fracturing in shale gas exploitation and geothermal extraction. [ABSTRACT FROM AUTHOR]

In chemically active rocks, pore pressure and stress state are not the only parameters that are governed by hydromechanical processes. Chemical osmosis is also responsible for changes in the effective stress caused by the presence of chemical potential between the reservoir and the borehole filled with drilling fluid. Subsurface rocks such as shales are highly anisotropic, and assuming an isotropic model will fail to provide an accurate depiction of the in situ stress state. In this work, governing equations for a fully coupled anisotropic nonlinear porochemoelasticity are developed. A numerical model using the FEM is constructed to simulate the drilling of an inclined borehole problem in an anisotropic and chemically active medium. The model accounts for solute transport contributed by diffusion and advection. Several sensitivity analyses are conducted to highlight different features of the chemohydromechanical model. Solute concentration, membrane efficiency, solute-diffusion coefficient, and advection are investigated. Results of this study show that the rock elastic anisotropy significantly enhances the stresses induced by the borehole excavation. Moreover, the presence of chemical potential has been shown to have a large bearing on the near wellbore stress state and pore pressure. It was demonstrated that this effect cannot be generalized and should be studied carefully on a case-by-case basis. Last, the model is used to analyze borehole stability for inclined boreholes under chemical, hydraulic, and mechanical loading. [ABSTRACT FROM AUTHOR]

Despite a body of research carried out on thermally coupled processes in soils, understanding of thermo-osmosis phenomenon in clays and its effects on hydromechanical behavior is incomplete. This paper presents an investigation on the effects of thermo-osmosis on hydraulic behavior of saturated clays. A theoretical formulation for hydraulic behavior was developed, incorporating an explicit description of thermo-osmosis effects on coupled hydromechanical behavior. The extended formulation was implemented within a coupled numerical model for thermal, hydraulic, chemical, and mechanical behavior of soils. The model was tested and applied to simulate a soil heating experiment. It is shown that the inclusion of thermo-osmosis in the coupled thermohydraulic simulation of the case study provides a better agreement with the experimental data compared with the case in which only thermal expansion of the soil constituents was considered. A series of numerical simulations are also presented, studying the pore-water pressure development in saturated clay induced by a heating source. It is shown that pore-water pressure evolution can be considerably affected by thermo-osmosis. Under the conditions of the problem considered, it was found that thermo-osmosis changed the pore-water pressure regime in the vicinity of the heater when the value of thermo-osmotic conductivity was larger than 10-12 m2·K-1·s-1. New insights into the hydraulic response of the ground and the pore-pressure evolution due to thermo-osmosis are provided in this paper. [ABSTRACT FROM AUTHOR]

The drag force law acting on a moving circular disk in a two-dimensional granular medium is analyzed based on the discrete element method (DEM). It is remarkable that the drag force on the moving disk in moderate dense and pure two-dimensional granular medium can be well reproduced by a perfect fluid with separation from the surface of the tracer. A yield force, being independent of the moving speed of the disk, appears if a dry friction between the granular disks and the bottom plate exists. The perfect fluidity is violated in this case. The yield force and the drag force diverge at the jamming point. [ABSTRACT FROM AUTHOR]

To characterize the role of specimen disturbance and structure in the hydromechanical behavior of collapsible soils, two sets of wetting-induced collapse and suction-controlled triaxial tests were conducted on intact and reconstituted specimens of a loessial soil taken from a loess deposit in Gorgan, a city in the northeastern Golestan province of Iran. The testing approach used an advanced triaxial testing device that was specifically modified to control pressures applied to a soil specimen and to monitor and measure the amount of changes in volume and water content of the soil specimens during testing using highly sensitive digital sensors with an accuracy of 60.01 cm³. Results of the wetting-induced collapse tests show that the collapse phenomenon in intact loessial specimens was mostly a stepwise reduction in volume rather than a continuous decrease with a constant rate or a sudden drop in volume as water entered the voids. This behavior is believed to be attributed to the nonhomogenous distribution of macropores or micropores in intact specimens, which results in the presence of void spaces with different degrees of collapse potential within the soil matrix. A comparison of the experimental measurements during wetting-induced collapse also indicated that soil structure has negligible effects on the behavior of collapsible soils at high values of mean net stress (i.e., 200 kPa or higher) but significantly influences the behavior under low mean net stresses (i.e., 50 kPa or lower). The shear strength values of reconstituted specimens were higher than those of intact specimens when sheared at the same applied mean net stresses and matric suctions. Observations from this study suggest that the use of a critical-state line generated based on reconstituted specimens is not suitable for the characterization of the behavior of natural loessial soils. Finally, the disturbed-state concept (DSC) was used to characterize the stress-strain behavior of the intact and reconstituted specimens of collapsible soils during shear. [ABSTRACT FROM AUTHOR]

Bioreactor landfills involving leachate recirculation are emerging as the preferred option for managing municipal solid waste (MSW). Effective bioreactor landfill performance can be achieved by ensuring uniform and adequate moisture (leachate) distribution in landfilled MSW. This paper presents a numerical two-phase flow model as a tool to predict hydraulic behavior (moisture distribution and pore fluid pressures) in unsaturated MSWunder leachate recirculation, mechanical response (stress-strain behavior), and coupled hydromechanical interactions of MSW in landfills. The selected mathematical model is the Fast Lagrangian Analysis of Continua (FLAC), which assumes leachate and landfill gas as two immiscible phases. The governing equations and numerical implementation are presented along with the general model implementation considerations. The model is validated by simulating the published laboratory studies, field studies, and published modeled studies. Overall, it is shown that the mathematical model is capable of providing information necessary for the design of effective bioreactor landfills by incorporating coupled hydromechanical processes. [ABSTRACT FROM AUTHOR]

Recent laboratory tests and field observations have revealed that unsaturated sands are susceptible to liquefaction. Systematic investigation of liquefaction potential of unsaturated sands is, however, lacking. In this paper, a coupled hydromechanical elastoplastic constitutive model for unsaturated sands is calibrated using available laboratory test results. A parametric study is then conducted using the calibrated constitutive model to investigate the effects of initial degree of saturation, relative density, and effective confining pressure on the liquefaction resistance of unsaturated sands. The results suggest that the liquefaction resistance of unsaturated sands increases with decreasing degree of saturation and increasing relative density and effective confining pressure. The results also reveal that the effect of degree of saturation on liquefaction resistance is more pronounced near 100% degree of saturation. The results of the parametric study are then condensed to create a design chart that can be used for liquefaction potential evaluation of unsaturated sands. The degree of saturation, relative density, and effective confining pressure are taken into account in this design chart. [ABSTRACT FROM AUTHOR]

Geomaterials with aggregated structure or containing fissures often exhibit a bimodal pore size distribution that can be viewed as two coexisting pore regions of different scales. The double-porosity concept enables continuum modeling of such materials by considering two interacting pore scales satisfying relevant conservation laws. This paper develops a thermodynamically consistent framework for hydromechanical modeling of unsaturated flow in double-porosity media. With an explicit treatment of the two pore scales, conservation laws are formulated incorporating an effective stress tensor that is energy-conjugate to the rate of deformation tensor of the solid matrix. A constitutive framework is developed on the basis of energy-conjugate pairs identified in the first law of thermodynamics, which is then incorporated into a three-field mixed finite-element formulation for double-porosity media. Numerical simulations of laboratory- and field-scale problems are presented to demonstrate the impact of double porosity on the resulting hydromechanical responses. [ABSTRACT FROM AUTHOR]

With a suction stress–based effective stress representation, stability analysis of unsaturated engineered and natural slopes can be performed effectively in the same manner as the classical limit-equilibrium (LE) methodologies. This paper presents an analytical framework for effective stress LE analysis of unsaturated homogeneous slopes under steady one-directional (vertical) flow. The proposed log spiral failure surface–based LE method involves only two additional hydromechanical parameters for unsaturated soil, approximating the inverse of the air-entry pressure and pore-size distribution. Both parameters are used to describe seepage and effective stress variations in unsaturated soils. Unlike most other LE formulations, the method is statically determinate. A parametric study was performed, and stability charts for general use are presented. The impact of infiltration and evaporation on the stability of slopes for four hypothetical soil types was studied. It is shown that the apparent cohesion due to suction stress may contribute substantially to the stability of slopes. Specifically, different seepage rates can significantly impact the stability of clayey slopes. This impact progressively decreases in silty slopes and further diminishes in loess and sand. Because the proposed method is statically free of assumptions, it can serve as a benchmark for rigorous slope stability methods that can deal with more complex problems. [ABSTRACT FROM AUTHOR]

The article discusses the contribution of physicist and mathematician, Evangelista Torricelli on his invention of the barometer and the study on fluid mechanics. It mentions Torricelli's study on the influence of water's inertia towards the changing in efflux velocity and change in vertical variation and the aspects of Bernoulli principles. It also explores the concept of potential and kinetic energy in Bernoulli's Efflux Theory.

A tsunami is a series of great waves primarily caused by a major subduction-zone earthquake with large-scale displacement of the sea floor or by initiation of submarine landslides. Many coastal areas in the western United States are subject to tsunami hazard that is infrequent but potentially extremely destructive. The public safety risk has been only partially mitigated through warning and preparedness of evacuation; there are many coastal communities in the states of Alaska, Washington, Oregon, California, and Hawaii where there is insufficient time for complete evacuation, and places of higher elevation and/or taller structures could provide life safety. Community disaster resilience would also require that critical and essential facilities provide structural resistance to collapse. Towards that goal, the Tsunami Loads and Effects Subcommittee of the ASCE/Structural Engineering Institute (ASCE/SEI) 7 Standards Committee has developed a new Chapter 6 with design requirements for tsunami loads and effects, contained in the 2016 edition of the ASCE 7 standard Minimum Design Loads for Buildings and Other Structures [Minimum design loads for buildings and other structures]. The ASCE 7-16 "Tsunami Loads and Effects" chapter will become the first national, consensus-based standard for tsunami resilience for use in the states of Alaska, Washington, Oregon, California, and Hawaii. The purpose of this paper is to provide an explanation of the technical basis and methodology for tsunami-resilient design of critical and essential facilities, tsunami vertical evacuation refuge structures, and other multistory building structures. The ASCE 7 provisions for tsunami loads and effects implements a unified set of analysis and design methodologies with design maps based on probabilistic hazard analysis, loads based on tsunami physics, and a structural ultimate strength basis of design. Probabilistic offshore tsunami amplitude maps and tsunami design zone inundation maps were developed using a method consistent with probabilistic seismic hazard analysis in the treatment of seismic source uncertainties. Procedures for tsunami inundation analysis are based on using mapped values of offshore tsunami amplitude or the runup and inundation limit shown in tsunami design zone maps. The ASCE 7 "Tsunami Loads and Effects" chapter is consistent with the principles of probabilistic hazard analysis, tsunami physics, and fluid mechanics, integrated into a comprehensive set of design provisions. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of the presence of a joint (vertically or horizontally oriented) on the hydromechanical behavior of sandstone under undrained triaxial conditions. A series of undrained triaxial experiments was performed on intact and horizontally and vertically jointed sandstone samples under different confining pressures and initial pore-water pressures. Joints in jointed samples were artificially created with rough and irregular surface profiles. An increase in pore-water pressure with increasing deviatoric stress was observed for all tests. Maximum induced pore-water pressure values were higher and occurred later in the jointed rock samples when compared to the intact samples at all confining pressures. This may be related to the efficiency of the response of the joint pore volume to loading when compared to that of the matrix pore volume. Moreover, the significance of new pore volume creation (by microcracking during failure) on sample pore-water pressure is dependent on the initial pore volume, which itself varies with the presence and size of joints regardless of orientation. Effective peak deviatoric stresses observed from the tests were consistently higher for the intact rock samples when compared to the jointed rock. This result suggests that the compressive strengths of intact and horizontally and vertically jointed rocks are not comparable when the joint is rough and the deformation is undrained. The origin of the influence of horizontal or vertical joints on rock strength may relate to the presence of edges on the rough joints, which act as stress intensification points and allow material failure under lower applied stress for the jointed samples than for the intact (homogeneous) samples. [ABSTRACT FROM AUTHOR]

This paper proposes an efficient framework for multiobjective optimization of the fuselage step on a large amphibious aircraft using a combination of computational aerodynamic and hydrodynamic methods. Both cruise drag and water take-off resistance and distance are calculated to evaluate the effects of the two key parameters, the longitudinal location and the depth of the step. A Reynolds-averaged Navier-Stokes (RANS) model was used for the calculation of cruise drag of the wing body configuration. Water take-off resistance and distance required for the baseline configuration were calculated using a volume of fluid method for hydrodynamic calculation and RANS method for aerodynamic calculation, respectively. A drag breakdown method was adopted to improve the efficiency of the hydraulic calculations. The method can achieve an accuracy of less than 5% difference compared to fully viscous calculations with only half of the computational time. The optimization is achieved using a combination of design of experiment and the response surfaces method. The optimized step configuration achieved an 18% improvement in take-off distance while maintaining similar cruise performance. The proposed method is generic and can be used in the optimizations of other components such as wings and fuselage geometries of amphibious aircraft. [ABSTRACT FROM AUTHOR]

Free surface, axially symmetric shallow flow is analyzed in both the centrifugal and centripetal directions. Referring to the inviscid steady flow over a flat plate characterized by a unique value of specific energy, the analytical sub- and supercritical solutions are determined. Furthermore, the sub- and supercritical steady solutions for the flow with friction over a flat plate are determined, provided that inertial terms are important compared with frictional terms. In the inviscid case, the sub- and supercritical solutions over a bottom topography are determined, provided that the bottom unevenness is compatible with a continuous solution. In the fundamental case of inviscid flow over a flat plate, the discontinuous solution also is analyzed for a direct hydraulic jump imposed by proper boundary conditions. In the simple scheme of an inviscid shock of zero length, the jump position and the sequent depths are analytically derived, thus indicating that all results are uniquely functions of one dimensionless number, i. e., the specific energy ratio between the sub- and supercritical flows. [ABSTRACT FROM AUTHOR]

Run-of-the-river hydropower is a typical form of power generation in mountainous regions. This study investigates the velocity field upstream of Aberfeldie dam, a run-of-the river facility on the Bull River nearWardner, British Columbia, Canada. As is typical for these types of run-of-the river facilities, the headpond of this dam is very shallow(approximately 1mdeep) because of long term sediment deposition. Near the facility's power intakes, a large scour hole has been created because of increased velocities induced by the intakes. This study conducted field measurements and developed a computational fluid dynamic (CFD) model to investigate the velocity field under various flow conditions. The CFD solver shows in a simplistic way that flow-induced bed shear stress likely causes a fluctuating, dynamic bed form that varies by season and the distance upstream, so that a consistent velocity pattern is seen across the entire headpond. The velocity field generated by the CFD solver is used to evaluate the entrainment risk of mountain whitefish and westslope cutthroat trout based on swimming mechanics and life stage. The unique habitat conditions generated by the scour hole act as an attractant to the high risk zone, greatly increasing fish density adjacent to the intakes at this facility. [ABSTRACT FROM AUTHOR]

Hydraulic analysis schemes for water distribution networks can be divided into demand-driven analysis (DDA) and pressure-driven analysis (PDA) according to the ways of calculating available outflow at nodes based on the assumption of nodal withdrawal estimation. Gradient algorithm-based numerical analysis schemes are generally used for these two types of hydraulic analysis. However, in abnormal conditions where hydraulic conditions rapidly change due to pipe damages or sudden increases in demands, the numerical solutions often derive unrealistic results that could lead to decision-making errors. In this study, the problems that may occur in hydraulic analysis of abnormal conditions were identified through sample cases using DDA and PDA models; then, the modification techniques resolving the simulation problems, the negative pressure in DDA and the total head reverse in PDA, were suggested. The proposed methods were verified by applying them to sample case study simulations. The application results reveal that the proposed approaches derive more realistic results under abnormal conditions, while the existing DDA and PDA tools produce unacceptable results, such as negative pressure and total head reverse occurrence. The scheme is further investigated for water network reliability evaluations and realistic ranges of demand supply under abnormal conditions were obtained. [ABSTRACT FROM AUTHOR]

A numerical model, called CST3 (Consolidation and Solute Transport 3), is presented for coupled one-dimensional large strain consolidation and solute transport in layered soils. The consolidation algorithm accounts for vertical strain, soil self-weight, general constitutive relationships, relative velocity of fluid and solid phases, changing compressibility and hydraulic conductivity during consolidation, unload/reload, time-dependent loading and boundary conditions, external hydraulic gradient, variable preconsolidation stress profiles, and multiple soil layers with different material properties. The solute transport algorithm accounts for advection, diffusion, mechanical dispersion, linear and nonlinear sorption, equilibrium and nonequilibrium sorption, porosity-dependent effective diffusion coefficient, and first-order decay reactions. CST3 is based on a dual-Lagrangian framework that separately tracks the motions of fluid and solid phases. The development of CST3 is first described, followed by verification checks. Numerical simulations indicate that layered soil heterogeneity and preconsolidation stress can have important effects on consolidation-induced solute transport behavior. Failure to correctly account for soil heterogeneity or preconsolidation stress profile can lead to significant errors in the analysis of consolidation and solute transport in layered soils. [ABSTRACT FROM AUTHOR]

Recent tsunami and hurricane-caused destruction, and the possibility of both tsunami inundation and storms of even greater magnitude and frequency making landfall in the future, has focused attention on the vulnerability of coastal structures, and bridges in particular. Findings from a series of experiments measuring forces on a 1:35 scale bridge model impacted by a solitary wave with varying percentages of air relief openings (AROs) between girders are presented here. A range of water depths, wave amplitudes, and elevations of the model above the still-water level (SWL) are considered. Results show significant reduction of vertical uplift forces when AROs are added to the bridge model, particularly when the girders are fully elevated above the SWL or only slightly submerged, but relatively little effect on horizontal forces in the direction of wave propagation is observed. Buoyancy calculations show added hydrostatic force does not alone contribute to uplift forces, but rather a combination of hydrostatic force, wave impact force, and deformation of the wave must all be considered. [ABSTRACT FROM AUTHOR]

Hurricane Katrina in 2005 displaced or washed away a number of coastal bridges, including the Biloxi Bay Bridge. Although some experimental and numerical studies have been conducted to reveal the failure mechanisms of bridges under extreme nature disasters, very few previous studies are focused on the bridge decks with inclinations. In the present study, the wave forces on the bridge decks with inclinations (-10°-10°) under solitary waves have been investigated using the Biloxi Bay Bridge as the prototype bridge. Seven different structure elevations are considered to represent different conditions in field. Wave forces under the prescribed conditions, including the horizontal forces, vertical forces, and moments are analyzed in detail. The results show that the characteristics of wave forces under solitary wave conditions vary with different deck inclinations and structure elevations. [ABSTRACT FROM AUTHOR]

The results of an experimental study of a drill-drop manhole used in the City of Edmonton, Alberta, Canada, are presented. A drill-drop manhole is a vertical drop manhole connected to a deep trunk sewer with an upper manhole and a lower manhole. The upper manhole diameter is only two or three times that of the lower manhole. Further, the flow in the upper manhole is dominated by the momentum of the incoming flow and as a result, the weir and orifice outflow types occurring in a relatively larger upper reservoir do not occur in drill-drop manholes. Instead, four regimes were discovered: deflected jet, stable pool, filling and emptying, and full pipe flow regimes. Dimensionless head-discharge curves were developed for the upper manhole for all flow regimes, and an expression for the sum of the losses in the upper manhole, including the entrance loss to the outlet pipe was found from the experimental results. Effects of outlet diameter and its length, inlet diameters, and their elevations were studied. [ABSTRACT FROM AUTHOR]

In a drained underwater cavity, seepage forces and pore-water pressure that develop around the cavity may affect the response of the rock mass. In this paper, a fully analytical solution is proposed for analysis of underwater cavities excavated in elastic-brittle-plastic and Mohr- Coulomb rock material, considering the induced seepage forces under steady-state flow. The initial stress state is assumed to be hydrostatic, and the seepage flow is assumed to be radial; thus, the problem is considered axisymmetric. In the proposed solution, in contrast to the failure processes that are represented as a function of Terzaghi's effective stresses, the induced deformations are considered as a function of Biot's effective stresses. The proposed solution is used to explain the behavior of cavities under different hydromechanical conditions. The results show that, in the case of drained cavities, seepage flow causes the induced radial displacements to increase and the stability of the cavity to decrease. From a practical point of view, the simplified analytical solution presented in this study can be used to approximate the design of circular cavities, such as a tunnel excavated below a water table, under seepage forces. [ABSTRACT FROM AUTHOR]

Detailed K-factors measured for a symmetrical nonreducing steel cross junction were published in this journal in 2010. This article describes a variable K-factor model for cross junctions that can take advantage of the published data and be incorporated into most existing hydraulic simulation software. The raw data are transformed and represented with bicubic spline surfaces. Newton's method is used to solve the system of equations resulting from linearization of the equations. Despite the variable junction K-factors, solutions converge quadratically or nearly so. For each iteration step, flow patterns must be detected, cross legs identified, and K-factors updated. Inherent complexity of flow through cross junctions creates challenges: K-factor surfaces have steep gradients and the values are often negative, branches with laminar flow occur alongside branches with turbulent flow, and flow stoppage is recurrent. In addition to comparing solutions based on constant and variable K-factors, intriguing flow phenomena are highlighted and suggested as research topics. An important application of the methods presented in this article is validation of hydraulic simulation software. [ABSTRACT FROM AUTHOR]

In this paper, the hydromechanical behavior of unsaturated soils is explored. A constitutive model is proposed to describe the coupled hydraulic and mechanical behavior of unsaturated soils. The compression stiffness parameters, such as λ(s), κ(s), λs, and κs, are analyzed, taking into account the influences of suction, degree of saturation, and net mean stress. Based on the volume change behavior under constant suction and the water retention properties, the relationship between the degree of saturation and volume change has been investigated under both net mean stress and suction. The proposed model is capable of describing the mechanical behavior of unsaturated soils for either isotropic compression or triaxial compression. Indeed, the simulation results of three cases of suction-controlled laboratory tests show good agreement with experimental data. [ABSTRACT FROM AUTHOR]

The tailings beach slope is a fundamental parameter for the design and operation of tailings storage facilities because it affects the tailings storage capacity, pond levels, and phreatic surfaces within the containment structures. Understanding tailings beach development is particularly important for thickened and paste tailings facilities, where the tailings can form a self-stacking structure. This paper presents a theoretical tailings deposition model that can describe the formation of tailings beach slopes in both subaerial and subaqueous deposition environments. The depositional behavior and deposition mechanisms are investigated from both geotechnical and hydraulic engineering perspectives. The model is developed to capture deposition mechanisms based on the principles of soil mechanics and fluid mechanics. The governing differential equations can be solved using a numerical technique, and the solution scheme can readily be implemented in computer languages. Case studies for subaerial deposition demonstrate that the modeling results are in agreement with laboratory flume testing and field measurements. The proposed model considers geotechnical and rheological properties of tailings, water pressures, operation parameters, and site topographic conditions. A sensitivity study was carried out to provide insight into the effects of influencing factors on the beach slope. [ABSTRACT FROM AUTHOR]

In recent years, a number of studies have been conducted to analyze wind-induced vibrations of a bridge using computational fluid dynamics (CFD). Previous studies have been limited to analyzing two-dimensional sections only, and three-dimensional (3D) analyses of entire bridges have not yet been performed. In this study, a CFD program with fluid-structure interaction is developed to perform buffeting analysis of a 3D cable-stayed bridge. The FEM formulated by the Galerkin least-squares method and arbitrary Lagrangian-Eulerian method are used to perform fluid-structure interaction CFD. The spectral representation method is used to generate the time series turbulence, which is applied to the inlet boundary condition. A supercomputer is used to reduce the large computing time. The analysis model of an existing cable-stayed bridge, which contains an ambient atmospheric region, has been used to calculate the dynamic responses of bridges and the detailed flow of wind. The results of the 3D CFD analysis of the bridge are compared with the results of conventional frequency domain buffeting analysis. The results are essentially in good agreement with those of the conventional analysis. The numerical method developed in this study will be an efficient alternative to wind tunnel tests for verifying wind flow, wind loading, and structural vibrations. [ABSTRACT FROM AUTHOR]

Prediction of damage caused by floodgate maneuvers is treated by the determination of factors amplifying the magnitude of generated damage. The identification of vulnerable areas is obtained by analogy with the water-hammer phenomenon in pressurized pipes. The numerical model is based on the Boussinesq assumption for transient flow in open channels and solved by the Mac-Cormack scheme. Transient flow concerns a rectangular channel where the initial steady state is uniform. Transient regime is provoked by the movement of a floodgate at the upstream extremity of the channel producing sinusoidal fluctuations of depth. A condition of floodgate closure is imposed at the downstream extremity. The applied excitation has permitted analysis of the fluid structure interaction, examination of pulsations provoking the resonance of the free-surface waves, and study of the evolution of depths according to time along the channel. According to the frequency of the movement of the floodgate at the upstream end, distortion of depth profiles or oscillations over these profiles may appear. The frequency value also has a significant effect on the flow depth evolution and can provoke the flooding of the channel. [ABSTRACT FROM AUTHOR]

In the present paper, the unsteady oscillatory stagnation point flow of a Jeffrey fluid is discussed. The oscillatory stagnation point flows have been discussed in a fixed frame of reference and a moving frame of reference. The convergence of the obtained analytical solutions has been discussed by plotting . Lastly, the physical significance of various parameters is discussed through graphs. [ABSTRACT FROM AUTHOR]

Detailed mean flow characteristics generated by a staggered arrangement of boulders in a rock-ramp-type naturelike fish pass were investigated experimentally at three different channel slopes (5%, 3%, and 1.5%). The results showed that this type of fish pass can produce adequate water depth and favorable flow velocity suitable for fish passage. Three different characteristic velocity regions were identified, namely, downstream of boulders (wake region), intermediate region, and upstream of boulders. Some general correlations were developed for predicting the flow depth and velocity in a rock-ramp fish pass as a function of normalized discharge. Moreover, a flow-resistance analysis based on basic concepts for wake-interference flow regime in this fish pass has resulted in a general equation for the average velocity. This study improves the understanding of the complex flow characteristics in a rock-ramp fish pass. [ABSTRACT FROM AUTHOR]

An experimental study of the supercritical dividing flow in a right-angle, four-branch junction with different channel widths is presented. Lateral-to-mainstream width ratios of , , and were used to establish the influence of the channel width on the flow distribution. A brief description of the flow characteristics is given. Types I and II flow patterns are confirmed by the experiments in the range of the studied variables. Existing flow distribution models were adapted for width ratios other than and tested for Type II, subregime 3 flow pattern, finding poor results. Other existing flow distribution models for Type II, subregimes 1 and 2 flow pattern and a width ratio of give a very good fit with the experimental data. A new flow distribution model for Type II, subregimes 1 and 2 flow pattern and width ratios of and was proposed, which is a function of the Froude number and the width ratio. A former model for predicting the flow distribution in equal-width ( width ratio) junctions was extended for width ratios of and . This model expresses the flow distribution as a function of the inflow power ratio and has the advantage over existing models that, for its application, the flow structure (angles of the oblique jumps) in the junction does not need to be determined beforehand. Although it is not necessary to apply the proposed flow distribution model, the flow structure (flow type and angle of the oblique jump or jumps, if presented) can also be predicted through the inflow power ratio, the inflow ratio, and the channel slope combination in the case of width ratios of and . [ABSTRACT FROM AUTHOR]

One of the great challenges of gravity settling is the difficulty of effectively removing suspended solids from the water column and retaining the settled particles in the settling basin under high inflow rates and short resident times. To address these issues, a new concept of using a bottom grid structure (BGS) for enhancing suspended solids removal by introducing a downward vertical vortex force and reducing disturbances of the bottom settled sediment was proposed and tested in the laboratory. A series of comparative laboratory experiments, without and with BGS, were carried out in a (D) tank. The experimental results revealed that for the tested flow rates ranging from 4 to , the removals of test particles with the BGS in the tank were about 10 to 30% higher than those obtained for the same conditions, but with a smooth tank bottom. Thus, the newly proposed BGS acts as a structure trapping and storing solids. In general, the improvement of particle removal rates was proportional to the inflow rate (or flow speed along the BGS top surface), before reaching a maximum value. This indicated that particles settled in the BGS cell on the tank bottom were effectively protected from disturbances by the fast bottom flows or external forces. To further examine the retention of deposited sediment by the proposed BGS, comparative experiments were conducted by placing particles on the tank bottom before activating inflow, with and without the BGS present. The results showed that for an inflow rate of , 67% of the placed particles were retained in the settling tank with the BGS; without it, the corresponding percentage was just 26%. Thus, the BGS retained 41% more of the particles settled in the bottom. A computational fluid dynamics (CFD) model was also used to describe the hydraulic conditions in the settling tank under various inflow rates and such results were helpful for establishing the relationships between the improved removal of suspended solids and the bottom flow speed and flow patterns in general. BGS offers a great promise of improving the performance of engineering facilities (e.g., stormwater detention ponds) serving to remove suspended solids from environmental flows. [ABSTRACT FROM AUTHOR]

Knowledge of microscopic geomorphic structures is critical to understanding transport processes in porous building materials. X-ray scans were obtained of a variety of commonly used porous building materials to both qualitatively and quantitatively evaluate their pore structures. The specimens included natural materials (two sandstones and a limestone) and engineered materials (three types of concretes and a brick). Scanned images were processed to reconstruct the geomorphic structures of these materials. Random walk analyses were performed on the reconstructed pore structures to estimate macroscopic transport properties (including tortuosity, specific surface, and permeability). The effective porosity and permeability of these materials were also experimentally determined and compared to computed values. Calibration of the threshold pixel value used in the postprocessing of X-ray images against measured effective porosity appears to be a more appropriate method of selecting this value than the typical approach, which employs selection based solely on observed histograms. The resulting permeabilities computed by using a calibrated threshold pixel value compare better with the measured permeabilities. This study also demonstrates that the relatively homogeneous and heterogeneous pore structures associated with the natural and engineered building materials under investigation can be captured by X-ray tomography. [ABSTRACT FROM AUTHOR]

This paper describes the theory behind a recent extension of a two-dimensional (2D) boundary-element code, FRACOD, to enable simulations of either coupled fracture (F)-hydraulic (H) processes or coupled F-thermal stress (T) in rocks. This extension is the next step in the ongoing development of a three-dimensional (3D) fracture mechanics code that couples F-H-T processes and predicts fracture initiation and propagation under thermal and hydraulic loadings. The original FRACOD simulated both mode I (tensile) and mode II (shear) fracture propagation that only involved mechanical processes in rock masses. In this study, the F-T coupling in FRACOD was developed using an indirect boundary-element method based on fictitious heat sources. The F-H coupling in FRACOD focused on fluid flow in explicit rock fractures using a cubic law. An explicit iteration method is used to simulate the fluid flow process in fractures and its interaction with mechanical deformation. Several verification and application cases have been included in the paper that demonstrate the effectiveness of the coupled functions. The extended code has been applied to the liquefied natural gas (LNG) underground storage experiment in South Korea and the Äspö pillar stability experiment (APSE) pillar spalling experiment in Sweden, and these applications are reported elsewhere. [ABSTRACT FROM AUTHOR]

In this study, the authors solve the shallow water equations (SWE) with smoothed particle hydrodynamics (SPH) for one-dimensional (1D) nonrectangular and nonprismatic channel flows with open boundaries. To date, 1D SPH-SWE has been only developed to simulate rectangular prismatic channel flows with closed and open boundaries. However, for practical hydraulic problems, channel cross sections are not always rectangular and prismatic. A general approach is proposed in this study to extend the engineering application range of 1D SPH-SWE to nonrectangular and nonprismatic channels with open boundaries by introducing the wetted cross-sectional area and the water discharge in SWE and combining the method of specified time interval with the inflow/outflow algorithm. Three benchmark study cases, aiming at testing various steady flow regimes in nonrectangular and nonprismatic channels, are adopted to validate the newly proposed approach. Through the investigation of the convergence analysis and numerical accuracy test of the study cases, the results show that the present SPH-SWE approach is capable to model 1D nonrectangular and nonprismatic channel flows with open boundaries. [ABSTRACT FROM AUTHOR]

The collection of floating woody debris at flow control structures, such as spillways and weirs, can potentially result in reduced discharge efficiency (higher upstream head for a given weir discharge). Compared to less hydraulically-efficient control structures, piano key weirs have higher discharge efficiency (lower upstream heads for a given discharge), which may increase the likelihood of woody debris collection. A systematic laboratory study was conducted to evaluate the interaction between various piano key weir geometries and woody debris types and sizes. The results of individual (noncumulative) debris tests indicated that floating debris blockage probability is highly influenced by trunk diameter and upstream head. The effects of debris accumulation on the upstream head varied with the value of the debris-free reference upstream head condition. At lower upstream reference head values, the cumulative debris tests indicated a relative increase of the debris-associated upstream head of approximately 70%; higher upstream reference head values produced upstream head increases limited to approximately 20%. [ABSTRACT FROM AUTHOR]

Water quality treatment via constructed storm-water wetlands (CSWs) is intimately linked to system hydraulics. Previous works have attempted to define the relationship between performance and wetland design variables (e.g., length, width, area). However, these works suffer from two major flaws: small sample size and/or nonrandom samples. The authors provide a framework herein to overcome these flaws. The goals of this research were to develop a methodology for creating randomly generated wetland designs and to use these designs to develop a set of equations for predicting peak flow reduction. Two thousand randomly generated wetland designs were generated using a five-tiered approach. Channel length and roughness were highly correlated with peak flow reduction and explained 83% of the total variability within the data set. Because of the large number of randomly generated designs, the regression equations presented herein prevent bias toward nonrandom designs. These equations represent the most general predictive performance equations developed to date and can be used to aid in CSW design. [ABSTRACT FROM AUTHOR]

New long-duration clear-water scour data were collected at single cylindrical piers with the objective of investigating the effect of sediment coarseness, ( = pier diameter; = median grain size) on the equilibrium scour depth and improving the scour depth time evolution modeling by making use of the exponential function suggested in the literature. Experiments were carried out for the flow intensity close to the threshold condition of initiation of sediment motion, imposing wide changes of sediment coarseness and flow shallowness, ( = approach flow depth). The effect of sediment coarseness on the equilibrium scour depth was identified; existing predictors were modified to incorporate this effect for ; and ; the complete characterization of a known scour depth time evolution model was achieved for , and . [ABSTRACT FROM AUTHOR]

The pressure-discharge relation used in continuity equations is one of the most important components of hydraulic models based on head-driven simulation method, as it has a great impact on the accuracy of the results of these models. Several pressure-discharge relations have been proposed and used in head-driven simulation method, but there are no laboratory and field studies available regarding the accuracy and correctness of these relations. In this research a laboratory set up and a field investigation in some parts of a real water distribution network are used to collect the required data. Flow discharge data from different faucets, based on laboratory and field measurements, are used to compare the proposed pressure-discharge relationships. Furthermore, in this paper, a new pressure-discharge relation is proposed for volumetric and human-based demands that is more reasonable than some previous relations and can be used in pressure-dependent models. [ABSTRACT FROM AUTHOR]

Vertical profile of longitudinal velocity in vegetated channels reflects complex mechanics of flow-vegetation interactions and determines the bulk flow velocity and flow rate. Most available models of velocity profiles in vegetated channels are based on a single physical concept that underpins theoretical considerations and data interpretation. However, measured velocity profiles suggest that the use of a single concept is not sufficient to cover all possible scenarios of flow-vegetation interactions. As a result, a number of models in which different concepts are applied to different flow regions have been recently developed. Within this framework, the overall velocity profile is represented with a set of linked segments. Although such segment-based models have improved velocity profile description, there is a need for more robust approaches and better analytical formulations. This paper proposes a new approach where a vertical velocity profile in vegetated channels is modelled as a linear superposition of four concepts: (1) uniform velocity distribution, (2) mixing layer analogy and a hyperbolic tangent profile, (3) boundary layer concept and a logarithmic profile, and (4) wake function concept. In contrast to the segment-based models, the proposed analytical expression combines these concepts simultaneously over the whole flow depth allowing significant overlaps of the momentum transport and turbulence production mechanisms. The model is tested using extensive laboratory experiments. [ABSTRACT FROM AUTHOR]

This paper presents a new, tractable analytical expression to describe the intrusion of fluids into buried pipes under steady-state conditions. The expression is validated with results from novel experiments. The derivation is based on the combination of the relevant existing models of flows through porous media and the losses through an orifice, with the resulting expression relating the intrusion flow rate to an applied driving pressure. The expression is shown to yield results directly equivalent to those generated from a full three-dimensional (3D) computational fluid dynamics (CFD) model of the intrusion process. Results from the experiments, quantifying volumetric intrusion from a realistic 3D porous media, presented here, compare favorably with calculated values, validating the expression. Although the experimental and analytical results show a high level of agreement, it was found that the analytical expression tends to slightly underestimate the intrusion rate seen experimentally. The absolute difference in the values is low and is thought to be attributed to preferential flow path at the porous media and pipe interface that the analytical expression and CFD model do not include. It is shown mathematically and verified experimentally that the viscous and inertial resistance to flow in the porous media reduces the intrusion (or leakage) flow over that predicted by the standard orifice equation and places additional dependencies of the flow on the size of the intrusion orifice. The values obtained from the expression should be considered as a lower bound to intrusion (and leakage) rates, with upper bounds being provided by the standard orifice equation. Although developed to aid in the quantification of intrusion risk, such as that associated with water distribution systems, the expression is also validated for leakage for the limited case that the external porous media is considered to be fully compacted, consolidated, and immobile. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) in landfill bioreactors is subjected to mechanical, biological, and hydrological processes. To understand these processes, four large-scale bioreactor pilots were specifically designed to simulate the behavior of waste in the core of a landfill. Here, the results of two long-term tests that were performed in two compression cells are presented. Mechanical, biochemical, and hydrological parameters were analyzed throughout the experiments. The promising results of this research improve the understanding of biodegradation and its correlation with the hydromechanical behavior of municipal solid waste. In particular, the sensitivity of the biodegradation to leachate injection and the correlation between the biogas flow and vertical settlement were confirmed for wastes with high initial moisture content. The results showed that it is important to consider the potential of different monitoring techniques and the representative volume for the experimental approach. Furthermore, the operational results led to interesting conclusions, especially regarding the addition of moisture to waste, which is a key element for bioreactor landfill operation. [ABSTRACT FROM AUTHOR]