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One-dimensional fourth-order boundary value problems (BVPs) play a critical role in engineering applications, particularly in the analysis of beams. Current numerical investigations primarily concentrate on homogeneous boundary conditions. In addition to its high precision advantages, the Hermite finite element method (HFEM) is capable of directly computing both the function value and its derivatives. In this paper, both the cubic and quintic HFEM are employed to address two prevalent non-homogeneous fourth-order BVPs. Furthermore, a priori error estimations are established for both BVPs, demonstrating the optimal error convergence order in H 2 semi-norm and L 2 norm. Finally, a numerical simulation is presented to validate the theoretical results. [ABSTRACT FROM AUTHOR]

With the excavation of underground opening, the roof rock block may fall under external dynamic disturbance. In this paper, the roof rock mass was simplified as a rock block system composed of trapezoidal rock blocks. A series of experiments and numerical simulations were performed to study the sliding process of the key block under the horizontal static clamping load and vertical impact disturbance. The propagation of stress wave in the block system were captured and analyzed by using high-speed camera and digital image correlation technique. The results reveal that a pendulum-type wave was generated due to the propagation and superposition of stress waves in the block system. Therefore, the governing mechanism of the sliding displacement of the key block was clarified based on the propagation of incident stress waves or pendulum-type waves. Meanwhile, it is found that the sliding distance of the key block decreases in a power function with the increasing friction coefficient, or decreases in a parabolic function with the increasing trapezoid internal angle. Finally, a case study on the roof block sliding of the roadway at a gold mine was conducted, and it is concluded that the sliding of the key block resulted from the coupled effects of "shear driving" and "low friction" driven by stress wave propagation, regardless of a single or multilayer rock block system. These results may provide technical guideline for preventing rock-falling accidents caused by blasting disturbances in underground mining. [ABSTRACT FROM AUTHOR]

The paper presents numerical simulation of polycrystalline titanium deformation in terms of the crystal plasticity theory. Based on the experimental data, a three-dimensional polycrystalline model is generated by a method of step-by-step packing. Constitutive relations for the deformation behavior of grains are based on the crystal plasticity theory with regard to the crystalline structure and dislocation glide in hexagonal closepacked crystal lattices. The boundary value problem of elastoplastic deformation is solved numerically using the finite element method. The proposed model is tested by elastoplastic deformation of titanium single crystals having different orientation. The proposed model is used to study the influence of the crystallographic orientation on localized plastic deformation in polycrystals. [ABSTRACT FROM AUTHOR]

The Hadamard fractional derivative and integral are important parts of fractional calculus which have been widely used in engineering, biology, neural networks, control theory, and so on. In addition, the periodic boundary conditions are an important class of symmetric two-point boundary conditions for differential equations and have wide applications. Therefore, this article considers a class of nonlinear Hadamard fractional coupling (p 1 , p 2) -Laplacian systems with periodic boundary value conditions. Based on nonlinear analysis methods and the contraction mapping principle, we obtain some new and easily verifiable sufficient criteria for the existence and uniqueness of solutions to this system. Moreover, we further discuss the generalized Ulam–Hyers (GUH) stability of this problem by using some inequality techniques. Finally, three examples and simulations explain the correctness and availability of our main results. [ABSTRACT FROM AUTHOR]

Zhao, J.; Wang, D., and Gu, H., 2015. Numerical simulation of dual laterolog in cavernous carbonatite reservoir. The cavernous reservoir has become one of the main carbonate reservoirs for stable and increasing production. The degrees and the types of fillings materials are the key factors which affect the characteristics of accumulation and flowage. However, due to the complexity of fillings in the caves, the response laws of logging of the cavernous reservoir can not be understood clearly and its effective evaluation has been severely hampered. This paper uses for the first time numerical simulation to study the responses in the curve of dual lateral log of cavernous reservoir. By establishing a continuous equation of the dual lateral log and its boundary factors and using the electric field superimpose principle, a finite element method is used to study the cave size, different filling agents and degrees are simulated. The result indicates that the size, filling agents and degrees show a clear response, and they have a clear correspondence. Summarizing and analyzing the response laws on the dual lateral logging curves of the cavernous reservoir can provide theoretical evidence for the logging evaluation of the carbonate cavernous reservoir. [ABSTRACT FROM AUTHOR]

This paper is a contribution to a better understanding of heat transfer through porous channels used for mechanical sieving and filtration of liquids. The problem modeled by means of the Navier--Stokes equations and the energy equation is similar to a viscous flow between two uniformly permeable walls fixed at different temperatures. Thermal behaviors are determined through three branches denoted solutions of types I, II and III of a diagram of bifurcations presenting the values of the wall shear stress as the Reynolds number varies. We found that the distribution of temperature is similar through branches I and II where a large horizontal inflection area is observed as the Péclet number increases. This large horizontal inflection area inside the channel denotes the presence of thermal boundary layers which more precisely occur across branches I and II when the Péclet number approaches the value of 10. On the other hand, along branch III, thermal boundary layers do not exist and temperature presents a different behavior compared to those of branches I and II. [ABSTRACT FROM AUTHOR]

The aim of this paper is to develop some well-adapted formulations for numerically solving the scattering problem of an incident time-harmonic wave by a cluster of circular cylinders. These formulations are illustrated by numerical simulations for different physical situations involving various kinds of boundary conditions. [ABSTRACT FROM AUTHOR]

We perform simulations in a gravitational collapsing model using the Einstein equations. In this paper, we review the equations for constructing the initial values and the evolution form of the Einstein equations called the BSSN formulation. In addition, since we treat a nonvacuum case, we review the evolution equations of the matter fields of a perfect uid. To make the simulations stable, we propose a modified system, which decreases numerical errors in analysis, and we actually perform stable simulations with decreased numerical errors. [ABSTRACT FROM AUTHOR]

A 1-D fluid model coupled with an external circuit is proposed to study the Xe dielectric barrier discharge (DBD) under a 50-kHz ac sinusoidal voltage. The impact of ions and photons on barrier surfaces and the thermal motion of charged particles in the sheath are taken into account in this model. The spatial and temporal distributions of electrons, ions, and excited, resonance, and metastable particles are investigated. The experimental investigations on discharge current densities under different voltage source amplitudes are analyzed and compared with simulation results. The results reveal that, with the increment of voltage source amplitudes, the waveforms of gas gap voltage and discharge current all move forward the applied voltage, showing a gradually decreased phase shift, which is in good agreement with the experimental observations. The evolution of surface charges accumulated on dielectric barriers can be divided into six stages during an ac cycle, and they play a key role in the ignition and extinction of the discharge. It is concluded that, while the charge difference between the surfaces of a two-side dielectric is up to a certain value and the applied voltage is low enough, the gas breakdown will occur. The spatiotemporal variations of particle densities and electric field indicate that the Xe DBD under the conditions considered in this paper is a typical glow discharge. Furthermore, the electron emission brought by impact of photons on dielectric surfaces can accelerate gap breakdown and strengthen the intensity of the discharge, and the sheath phenomenon is more obvious under the consideration of thermal motion of charged particles in boundary conditions. [ABSTRACT FROM AUTHOR]

This paper presents a computational fluid dynamics (CFD) study of vortex-induced vibration (VIV) for different aspect ratio (L/D) cylinder. Of particular interest was to measure hydrodynamic forces and numerically investigate the wake behaviour of VIV while varying the aspect ratio. The simulation models represented the actual experimental conditions with idealised free-surface boundary condition to capture the responses from fluid-structure interaction phenomenon. The simulations were performed in the subcritical flow region (7.4×103< Re < 2×105), corresponding to a range of reduced velocity (Ur) from 2 to 14. The results of the cases studied were discussed and compared with the experimental data to verify the accuracy and validity of the present simulation. The comparisons have shown a similar curved-shape drag coefficient plot, and however underestimated the value of the drag coefficients over the reduced velocity. Additionally, the simulations seemed to capture a higher lift force response compared with the experimental data for a low aspect ratio. The correlation length was observed to be longer for larger aspect ratio and proportionally decreases as the aspect ratio decreases. [ABSTRACT FROM AUTHOR]

Transient analysis of the pipe flow is often more important than the analysis of the steady state operating conditions that engineers normally use to withstand the additional loads resulting from instantaneous rapid valve closures. The flow rate and fluid pressures in the system may change from significantly high to an extremely low magnitude after some time interval of valve closure. These types of unsteady flows are frequently encountered in sudden closing of upstream valve of a turbine in hydroelectric power station. The governing equations of unsteady flows in closed conduits are partial differential equations of hyperbolic type. One simple numerical solution technique available in the literature is the method of characteristics (MOC). In the current paper, the MOC model is explained through one case study of valve closure. One bench mark problem of reservoir on upstream end and a valve on the downstream of pipeline end is demonstrated in this paper. Fluid pressure and flow rate variations in pipeline with respect to time after the valve closure are arrived from MOC model. It is observed that pressure head increased after development of first pressure wave which is due to instantaneous closure of the valve at the downstream end of the pipe. The pressure head and flow rates are not dampened but they were found to be oscillating by increasing and decreasing in the total simulation time which may be due to wave propagation time and consideration of series pipe of different diameters in the current study. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we consider a variable-territory predator–prey model with Dirichlet boundary condition. We establish a necessary and sufficient condition for the existence of positive solutions to steady state. Furthermore, we also prove that the local bifurcation positive solutions are unconditional stable. By regular perturbation theorem, we investigate the convergence and stability of positive solutions when handling time m is large enough. At the end of this paper, there are some numerical simulations and biological significance to check and complement our theoretical analysis results. [Copyright &y& Elsevier]

Abstract Cyclic stress paths in geotechnical experiments can generate considerable principal stress rotation (PSR) in the saturated soil. The PSR without changes of principal stress magnitudes can generate additional excess pore water pressures and plastic strains, thus accelerating liquefactions in undrained conditions. This paper simulates a series of laboratory tests considering the PSR using two types of sand. The impact of PSR is taken into account by using an elastoplastic soil model developed on the basis of a kinematic hardening soil model with the bounding surface concept. The soil model considers the PSR by treating the stress rate generating the PSR independently. The capability of this soil model is verified by comparing the numerical predictions with and without PSR, as well as experimental results. The comparative results indicate that the simulation with the soil model considering the PSR can better reproduce the test results on the development of shear strain, reduction of effective confining pressure and liquefaction than the soil model without PSR. Therefore, it is important to consider PSR effects in simulations of geotechnical experiments under cyclic loadings. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, numerical results of a drop weight impact test examining the dynamic response of a clamped steel beams struck transversely at the centre by a mass with a rectangular indenter are presented. The numerical simulation showed that the results are very sensitive to the way in which the supports are modelled and thus this paper studies the modelling of the structural supports used to clamp the specimen beam in the experiment. The first approach simplifies the structural support as boundary condition on the nodes; the second model represents the entire support as the real approximation; the last approach uses simplified support plate model acting with the beam to simulate the experimental set up. The complete force–displacement curve is used to compare the plastic deformation of the impacted beams, thus the best approximation is selected for further calculations. The finite element model was performed using the LS-DYNA non-linear, dynamic finite element software. The numerical calculations can predict accurately the response of deflections, forces and absorbed energies, when proper boundary conditions are applied, in this case with shell elements representing the support plates. [Copyright &y& Elsevier]

The breakage of cutter ring during shield tunnelling is studied in this paper. The field observation reveals that the major reason for the cutter ring breakage is attributed to the unbalanced forces between two sides of the cutter ring during cutting process. Based on the three-dimensional (3D) circular cutting analysis, a semi-theoretical equation for the inner side force acting on the cutter ring is derived, by assuming that the cutting groove in the rock sample is caused by shearing failure. Numerical simulations are performed to determine the effect of angular velocity and further verify the proposed equation for the inner side force. Based on the proposed equation, the following influential factors for the magnitude of inner side force can be identified: i) circular cutting radius, ii) penetrating depth, and iii) angular velocity. The contribution to the inner side force from the above factors is discussed then. Finally, the relationship between cutter ring breakage and inner side force is analysed, which indicates that the inner side force has a significant effect on the breakage of the cutter ring. [ABSTRACT FROM AUTHOR]

This paper introduces a new spontaneous potential log model for the case in which formation resistivity is not piecewise constant. The spontaneous potential satisfies an elliptic boundary value problem with jump conditions on the interfaces. It has been shown that the elliptic interface problem has a unique weak solution. Furthermore, a jump condition capturing finite difference scheme is proposed and applied to solve such elliptic problems. Numerical results show validity and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The computational simulation of rivers is a useful tool that can be applied in a wide range of situations from providing real time alerts to the design of future mitigation plans. However, for all the applications, there are two important requirements when modeling river behavior: accuracy and reasonable computational times. This target has led to recent developments in numerical models based on the full two-dimensional (2D) shallow water equations (SWE). This work presents a GPU accelerated 2D SW model for the simulation of flood events in real time. It is based on a well-balanced explicit first-order finite volume scheme able to run over dry beds without the numerical instabilities that are likely to occur when used in complex topography. The model is applied to reproduce a real event in the reach of the Ebro River (Spain) with a downstream reservoir, in which a study of the most appropriate boundary condition (BC) for modeling of the dam is assessed (time-dependent level condition and weir condition). The whole creation of the model is detailed in terms of mesh optimization and validation. The simulation results are compared with field data over the flood duration (up to 20 days), allowing an analysis of the performance and time saved by different GPU devices and with the different BCs. The high values of fit between observed and simulated results, as well as the computational times achieved, are encouraging to propose the use of the model as a forecasting system. [ABSTRACT FROM AUTHOR]

Heat treatment of the weld of the steam generator is investigated in this paper. Annealing is realized by system of heating elements that are placed on casing of the generator. An experiment using real parameters and a computational fluid dynamics analysis using COMSOL Multiphysics software were performed. Experimental data were compared with results of the analysis. Boundary conditions for numerical prediction had been derived on basis of results obtained from a supplementary calibration experiment. There was good correlation between predicted and measured data. Based on results it can be stated that 67 heating elements with heating output of 60-70% of maximum range is sufficient number for required heat treatment. [ABSTRACT FROM AUTHOR]

In this paper, we report on a miniaturized device that can generate multiple jet flows circulated in a confined system. The device has a flow network comprised of four symmetrical working chambers connected with a pump chamber. The pump chamber is actuated by a PZT diaphragm. The flows in the device are studied by a computational fluid dynamics simulation and experimental measurements. The numerical simulation is carried out with programmable open source OpenFOAM, where the vibration of the PZT diaphragm is modeled with a newly developed boundary condition. Flow inside the device is verified by two hotwires embedded in each working chamber. It was confirmed that the flows generated in the four sensing chambers were almost identical. The performance of the device can be customized either by fluidic parameters, such as the driving voltage on the diaphragm, or by heat transfer processes, such as heating current of the hotwire or by alternating the gas media. The device is robust, ready-to-use and minimal in size. These are important features that can contribute to the development of multi-axis fluidic inertial sensors, fluidic amplifiers, gas mixing, coupling and analysis. [ABSTRACT FROM AUTHOR]

We present effective methods for the numerical simulation of high-power-pumped continuous-wave (CW) and pulsed erbium-ytterbium-codoped fiber amplifiers (EYDFAs). For CW EYDFAs, a novel initial guess method and a robust algorithm are proposed to ensure the convergence of the boundary-value problems involved in the solution of the numerical model. For pulsed EYDFAs, an efficient finite-difference method based on the Lax-Wendroff scheme is developed. With these methods, high-power CW or pulsed EYDFAs can be simulated. As an example, a high-power pulse-pumped low repetition rate EYDFA is analyzed. Besides demonstrating the proposed methods, the simulation results show that the optimal pulse width of the pump can be determined by the power of the backward Yb-ASE, and the time delay between the signal and pump pulses play an important role in optimizing the performance of a high power pulse-pumped EYDFA. [ABSTRACT FROM AUTHOR]

To research the performance of a solid fuel scramjet combustor, a solid fuel regression rate model was coupled into a quasione- dimensional flow equation, and so the flow parameters and fuel regression rate could be calculated together. According to the regression rate and the combustor diameter in the previous moment, the combustor diameter of the next moment could be obtained. The unsteady combustion and flow matter in the combustor was simplified into a steady calculation of every moment by solving the boundary condition at different moments independently. The numerical results were compared to actual experimental data from the literature, and they agreed well with the experiment. Taking the fuel/air ratio and Mach number as the optimization conditions, the initial size of the combustor could be obtained. On the basis of an optimized combustor, the relevant parameters' variation rules were calculated and analyzed. It was found that during the working process, the combustor flow field could be kept at the supersonic flow state, the axial fuel regression rate at a specific moment first increases and then tends to be steady, the local fuel regression rate at a specific position decreases gradually with time, the mass flow rate at the combustor exit and the fuel/air ratio is relatively steady, and the total pressure recovery coefficient and the specific impulse of the combustor decline gradually. [ABSTRACT FROM AUTHOR]

The level of pollution concentration to the archeological site Viminacium caused by the stack of Kostolac B power plant is analysed using CFD software. The wind is directed from the stack toward Viminacium-Archeological Site, Therma and Viminacium-Museum. Three different meteorological conditions resulting in fanning, fumigating, and looping plume are modelled. The temperature gradient as the most important factor defining the conditions of the atmosphere is included through the appropriate boundary conditions. It is shown that concentrations of the pollutants on the objects of Viminacium are very low. It can be attributed to the stack height and high temperature of the smoke at its exit. It also indicates that other sources of pollution such as open ash dumps and acid rain should be checked. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics (CFD) gradually plays an important role in the evaluation of the wind tunnel design project. This paper is about the evaluation results of the slotted test section of 0.6m x 0.6m continuous transonic wind tunnel including alternative design and flow field quality, especially comparing full slot with half slot. It presents the control equations and boundary conditions for numerical simulation firstly. Then the details of numerical results about the high subsonic and low supersonic flow characteristic are given. The length of velocity uniformity region and velocity deflection angle meet the design accuracy and that proved the rationality. The half slot project was better than the full one at high subsonic. Low supersonic field could be achieved when air was bleed from plenum chamber. However, more bleed air rate, shorter length of velocity uniformity region. Full slot project had less disorder on flow of the plenum chamber than the half. Further investigation on the flow mechanism of re-entry flaps indicated that the flow was unsteady one significantly. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the geometric model, combustion model and the initial and boundary conditions were determined by the actual long narrow confined space. The variation of the temperature field at different time were studied, the temperature distribution law of long narrow confined space were simulated by detection points, which including the dome temperature variation at different time, and the temperature distribution law in the horizontal and vertical direction, the law of temperature distribution in the three directions were studied when the simulation was 120s. The study provided reference for evacuation and rescuing of long narrow confined space fire under the negative pressure ventilation condition. [Copyright &y& Elsevier]

Abstract: The paper presents some aspects related to boundary conditions perturbing measurements during dynamic compression performed with a Split Hopkinson Pressure Bar (SHPB). The analyses are focused on the influence of such effects like friction, inertia, punching, elastic wave dispersion and contact zone shape between the input bar and the projectile on the estimation of dynamic material properties. Taking these experimental restrictions and influences into account allows for better understanding of the measurements used to define the thermoviscoplastic material behavior. The results of these tests together with presented numerical simulations enable for a better understanding of the phenomena and the reduction of errors which accompany the measurements in compression testing at low and high strain rates. [Copyright &y& Elsevier]

Abstract: Thermoplastic composite materials offer new perspective in the mechanical industry, especially in aeronautic industry. The assembly of huge structures by welding is made possible by the ability of the matrix to melt. This paper focuses on ultrasonic welding process where heating is confined at the welding interface. This is achieved thanks to a local mechanical dissipation in triangles specially located at the interface, called energy director. In order to better understand the phenomena that occur at the energy director scale, we propose to model and simulate the polymer flow at the interface. Based on a previous work, the flow under vibration is modeled using three coupled boundary value problems. A specific simulation tool is then developed for solving those three problems. It entails specific numerical methods: a level set method allows to handle the large geometry change, and an iterative solver manages the multiphysical aspects. The novel simulation obtained is validated with a qualitative comparison to experiments. Then, an analysis of the numerical results allows to understand the phenomena that enable welding. A thermomechanical localization heats the tip of the energy director. This initiates a fold of polymer that progressively fills the gap between the two plates to weld, and ensures conditions for adhesion. [Copyright &y& Elsevier]

Abstract: In this paper, we present a saline aquifer showcase model from the North German Basin, predicting the regional pressure impact of a small industrial scale CO2 storage operation on its surroundings. The static model is based on real geology while the injection program is fictitious. We simulated a rate controlled injection of 2.5 Million tons CO2 per year through a single vertical well into the structural top of a dome shaped anticline, over a period of 10 years. The target is a 20 m thick sandstone layer intercalated in low permeability claystone sequences. We used ECLIPSE300 with its CO2 storage module and MUFTE-UG to predict pressure at the top of the target sandstone layer in 1, 5, 10, and roughly 31 km distance to the injection point. The farthest point represents the structural top of a neighbouring anticlinal dome, another favourable potential storage site. We varied the model’s boundary conditions, permeability, permeability anisotropy, rock compressibility, and injection temperature. A total of nine model scenarios were run, five with MUFTE-UG and another four with ECLIPSE. Comparison of reference scenarios showed that the results of both simulators match well. In the open boundary model, pressure increase is lowest and dissipates back to the pre-injection state within 30 years after injection shutdown. In the fully closed models, pressure peaks are high, equilibrating to a remnant, model-wide overpressure several decades after the end of injection. In the distance, this equilibrated, model-wide overpressure is the actual maximum pressure. In the model scenarios which are laterally half open, half closed, pressure relief is seriously retarded in comparison to the fully open model. In all cases, the pressure maximum arrives at the neighbouring structure (31 km distance) years after the actual injection shutdown. Rock compressibility impacts both the peak pressure and the speed of the pressure build-up and relief. High permeabilities are more important in the immediate injection area than for the regional footprint. In all of our fully closed (i.e. the most pressurized) models, the remnant regional overpressure amounted to about 9 bars. If 10 bars are taken as the maximum tolerable overpressure, then the volumetric storage capacity of the target structure itself is not affected. However, injection into the target structure does affect the storage capacity of the neighbouring site. While a purely volumetric approach yields a cumulative storage capacity of roughly 175 Mt for both structures, a tolerable regional overpressure of 10 bars lowers the joint storage capacity to about 32 Mt CO2. Exactly what regional pressures are tolerable for a given aquifer, however, needs to be determined on a site specific base. [Copyright &y& Elsevier]

The aim of this article is the comparison of input options of river boundary condition of MODFLOW - three-dimensional numerical simulation model of groundwater flow. The water level in stream flowing through territory of hydrogeological layer can be computed via three built-in modules: River, Stream and Streamflow-Routing. In this study the code MODFLOW is used to simulate idealized aquifer and stream. The differences between computed groundwater table showed to be minimal, thus in case of modules Stream and Streamflow-Routing they are equally usable as using module River with external one or two-dimensional simulation of surface water flow, which is more time-consuming process. However, this applies only to idealized, simplified conditions of the modeled environment. For more complex simulation of flow in streams with irregular structure of the streambed is necessary to use either an external simulation or use the Streamflow-Routing module, which includes the possibility to enter more complex hydraulic flow parameters in the model. [ABSTRACT FROM AUTHOR]

Inland boundary conditions have significant impacts on seawater intrusion (SWI) due to sea-level rise (SLR). This study investigated the impacts of three inland boundary conditions (flux-controlled (FC), head-controlled (HC) and general-head boundary (GHB)) on modeling SWI due to SLR in coastal aquifers. First, we used the TOUGH2/EOS7 software program to solve the standard Henry's problem and compared the results with those from the literatures. Numerical simulations were performed to investigate the impacts of the three inland boundary conditions on SWI induced by SLR in confined coastal aquifers (standard Henry's problem) and unconfined coastal aquifers (Henry's problem extended to unconfined domains). The simulation results show that HC systems in both confined and unconfined coastal aquifers are remarkably vulnerable to the effects of SLR owing to the resulting decreased head difference, while FC systems are relatively insensitive to SLR because the equivalent freshwater head at the inland boundary can increase by a similar magnitude to the SLR. The GHB boundary is more realistic than the other two boundary conditions: the recharge decreases because of SLR depending on the aquifer properties and the head difference between the reference head and the equivalent freshwater head at the seaside boundary. [ABSTRACT FROM AUTHOR]

A spatially resolved three-dimensional microscale model of a lithium-ion battery half-cell is developed and applied to periodic electrode microstructures made up of spherical particles following a bidisperse particle size distribution. The geometries of the periodic unit cells are derived from discrete element simulations using periodic boundary conditions. Three different particle arrangements, which consist of two layered structures and one mixed particle array, as well as three different compression rates, are considered. In the study, the cathode is assumed to consist of LiMn2O4 as active material. Layered particle arrangements comprising the particle fraction of the smaller particle size in the region close to the separator are found to be beneficial especially for high-rate applications. According to the simulation results, the high-rate capability is reduced upon compression of the electrode microstructures. [ABSTRACT FROM AUTHOR]

Spinning process is investigated to reveal the mechanism of square cross-section spinning without mandrel. The finite element model with the roller path formula as a boundary condition is established. Forge3D software is used to simulate the spinning process, and the accuracy of the finite element model is verified through experiment. From the stress-strain field, the residual stress on the surface of the workpiece is small after square cross-section cone hollow spinning and the maximum deformation locates on the middle part of the slope surfaces of the workpiece. The strain field distribution and the same Δr in different rotation round are the cause of the slight curvature that appears on the cross-section edge. The wall thickness decreases after hollow spinning, and the upper wall thickness is larger than the lower part. [ABSTRACT FROM AUTHOR]

Barotropic and baroclinic oscillations typical of the spring period have been studied based on the three-dimensional thermohydrodynamic model of the Black Sea. This season can be considered transient between the termination of the effect of strong winter winds and the onset of seasonal thermocline formation. The three-dimensional numerical model with a free surface and boundary conditions, corresponding to the real wind field for April 2006 and to the heat and salt flows on the surface, has been used. The horizontal and vertical spatial resolutions of the model are 1.5 km and 27 levels, respectively; the time discreteness is 1 h. This makes it possible to perform detailed modeling in the South Coastal Crimean sea sector. The spatial-time structure of the level, kinetic energy, and temperature fields has been studied using the spectral analysis method. The maximal energy-carrying frequency has been interpreted. Manifestations of Poincare and Kelvin waves, as well as captured shelf waves, have been distinguished in the submesoscale spectral region. A comparison with previous studies has been performed. It is indicated that the stratification variability caused by synoptic processes affects spectral characteristics of wave processes on smaller scales, making its contribution to the Black Sea water mixing. [ABSTRACT FROM AUTHOR]

A numerical simulation for the modeling of solar kilns for hardwood timber drying with different boundary conditions has been developed in this work. This simulation has been used to predict the key behavior of the wood and the kiln itself under different geographical and weather conditions in Australia. This work, therefore, enables a site to be suggested that is likely to give the best kiln performance both in terms of the productivity and the quality of the end-use product. As test cases, realistic climatic conditions for three representative geographical locations in Australia, including Sydney (latitude 33.86°S), Melbourne (37.81°S), and Brisbane (27.46°S), have been considered in this simulation. Out of the three sites considered in this work, the fastest drying rates (and highest diffusion coefficients) were predicted in Brisbane. The highest level of instantaneous strain in the timber for this location was also predicted to be 0.0075 m/m, which is much less than the failure value (0.02 m/m). The moisture content distribution profile within the boards toward the end of the drying period was found to be almost uniform, which is likely to cause low degrade in the dried timber. [ABSTRACT FROM PUBLISHER]

In this research, the three-dimensional flow of metal in friction stir welding (FSW) has been simulated based on computational fluid dynamics. Conservation equations of mass, momentum, and energy were solved in three dimensions. The interactive force was imposed as boundary conditions on the tool/material boundary in the model. The strain rate- and temperature-dependent non-Newtonian viscosity was adopted for the calculation of metal flow. The distribution of temperature, velocity, and strain rate were simulated based on the above models. The simulated temperature distribution agreed well with the experimental results. The simulation results showed that the velocity on the pin was much higher than that on the shoulder. From the comparison between the simulation results and the experiments results, contours line, corresponding to strain rate = 4 s, reflected reasonably well the shape of stir zone, especially at the ground portion. [ABSTRACT FROM AUTHOR]

We present a theoretical study of the abnormal deformation of micro-beams induced by a droplet placed on their top/bottom surfaces. The bending moments and deflections of the micro-beams are derived in consideration of the surface tension and Laplacian pressure difference of the droplet. The deflection curves show that the cantilever inevitably tilts upwards with a droplet on its top surface, and most parts of the simply supported beam and clamped–clamped beam will bend upwards when a droplet is adhered to their bottom surfaces. These anomalous deformation behaviors have been verified by our finite element simulations. We also demonstrate what extent of the boundary conditions will affect the deflection curves of the micro-beams during the variation of the droplet’s parameters. Understanding this abnormal bending mechanism of the beams can be beneficial to some industry applications, such as the micro-electro-mechanical systems (MEMS) and the micro/nano-measurement, which can provide the inspiration of engineering more precision micro-sensors. [ABSTRACT FROM PUBLISHER]

Counter-current spontaneous imbibition is one of the main displacement processes in fractured reservoirs. Determination of an imbibition face boundary condition has been the main challenge in this area. A recent work presents a new approach that proposes a solution to specify this boundary condition in the case of infinite core length, which results in a saturation less than the maximum reachable wetting phase saturation. The new method is applicable only in the case of infinite cores and cannot be applied in the case of counter-current spontaneous imbibition in matrix blocks of fractured reservoirs that are finite in length. The case of finite core, which includes a dead end, makes the situation very complex and a new challenge in this area. The present article presents a solution for specifying an imbibition face boundary condition when the imbibition front reaches the dead end of the core. The methodology is based on the investigation of the physics of the counter-current imbibition process in a finite core that includes a dead end. Numerical simulation was used to compare the non-wetting phase recovery rate by implementing different boundary conditions in one- and three-dimensional blocks. The results for the one-dimensional core show that the rate of oil recovery during counter-current spontaneous imbibition is higher when imbibition face saturation is higher, but the recovery fractions reach the same value and rate at late times. For a matrix block, it was illustrated that the new boundary condition leads to a higher recovery rate. [ABSTRACT FROM PUBLISHER]

The semidiscretise Method of Lines (MOL) is used for the numerical analysis of transient phenomena occurring during the operation of natural gas pipelines and pipe networks. The Method of Lines discretises the spatial terms of the governing equations, reducing the partial to an ordinary differential equations system which can be solved by various techniques. For comparison and validation purposes, transient phenomena are also simulated here by means of the Method of Characteristics (MOC) which is a reliable but rather old method. The governing equations system is based on the fundamental conservation laws of mass, momentum, and energy for the unsteady one dimensional compressible pipe flow. Experimental results representing realistic transient pipeline phenomena have been obtained from the laboratory test facility. The agreement between numerical results of both methods and measurements is satisfactory especially when experimental data are introduced as time dependent boundary conditions. In addition the Method of Lines proved efficient and applicable to rapid as well as to slow transients which is a very common unsteady behaviour of natural gas pipeline flows. [ABSTRACT FROM AUTHOR]

Two diffraction gratings placed in front of a fiat surface generate an interference pattern representing the surface deformations. The local deformation about fatigue cracks has been investigated by the coherent optics method of moire interferometry. The complexity of the interference fringe patterns motivated the parallel development of companion numerical models for simulating moire interferometric response for known boundary conditions. Experimental patterns are here examined in the light of computer-generated fringe systems for a stationary crack in elastic as well as elastoplastic solids. Various effects due to material plasticity, specimen- dependent nonsingular stress, and mixed mode loading are identified in the fringe patterns. The high sensitivity of moire interferometry permits quantitative analysis in the small-strain domain. We discuss the theory used and obtain general expressions for evaluation of slope and curvature by means of projection moire. Severally examples models illustrate possible application of model and the method proposed. [ABSTRACT FROM AUTHOR]