THE INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS AND EXPERIMENTAL MEASUREMENTS最新文献

{"title":"Optimization of a single-storey timber building structure","authors":"S. Kravanja, T. Zula","doi":"10.2495/CMEM-V9-N2-126-140","DOIUrl":"https://doi.org/10.2495/CMEM-V9-N2-126-140","url":null,"abstract":"The paper deals with the optimization of a single-storey timber building structure designed from timber portal frames connected with steel purlins, rails and façade columns. While the portal frames are made of the glued laminated timber with rectangular cross-sections, purlins, rails and façade columns are made of commercially available steel I-profiles. The portal frames are supported by square concrete pad foundations. The building structure is optimized by a mixed-integer non-linear programming (MINLP). The optimization model is developed. The objective function defines the material costs of the structure. The objective function is subjected to structural analysis and design constraints defined according to Eurocode standards. The Modified Outer-Approximation/Equality-Relaxation algorithm (OA/ER) and the linked multi-level strategy are applied. The optimization determines the minimum material costs of the structure, the optimal number of glulam frames and steel members and all standard/discrete crosssections. A numerical example at the end of the paper shows the efficiency of the proposed optimization approach.","PeriodicalId":22520,"journal":{"name":"THE INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS AND EXPERIMENTAL MEASUREMENTS","volume":"10 1","pages":"126-140"},"PeriodicalIF":0.0,"publicationDate":"2021-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87823818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pitting corrosion analysis of stainless steel by boundary element method with strain-dependent polarization curve","authors":"O. Kuwazuru, A. Kawakami, Y. Miura, E. Divo, A. Kassab","doi":"10.2495/CMEM-V9-N1-51-62","DOIUrl":"https://doi.org/10.2495/CMEM-V9-N1-51-62","url":null,"abstract":"This study aims at evaluating the corrosion rate at the first stage of stress corrosion cracking by a numerical simulation. The stress corrosion cracking starts with a pitting corrosion which appears from a damaged portion of passive film induced by plastic deformation. From micromechanical standpoint, the stress and strain are concentrated around the grain boundaries due to the heterogeneity of microstructures; therefore, the plastic slip occurs mainly around the grain boundaries and generates a fresh surface without passive film. This produces a microcell and affects the macroscopic polarization curve. We obtained this polarization curve of stainless steel from the open-circuit tensile tests associated with the microscopic electrostatic simulations. Moreover, this paper shows the two-dimensional formulation for coupling analysis of elastic stress and electrolytic potential. Both fields are solved by the boundary element method with the discontinuous quadratic element. The strain-dependent polarization curve is used as a nonlinear boundary condition of the potential problem. First, the elastic problem is solved to obtain the surface strain which governs the polarization curve on the surface. Next, the potential problem is solved to obtain the current density on the surface which determines the corrosion rate. Since each node has two corrosion rates in different directions coming from the neighbouring elements, we average these two rates and directions, so as to conserve the volumetric reduction rate unchanged. After moving the nodes as a result of corrosion during the time step, we return to the stress analysis and iterate this procedure during the interested period of time. We demonstrate a corrosion pit growth from a small hemi-elliptic surface defect and show the availability of the proposed method.","PeriodicalId":22520,"journal":{"name":"THE INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS AND EXPERIMENTAL MEASUREMENTS","volume":"16 1","pages":"51-62"},"PeriodicalIF":0.0,"publicationDate":"2021-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82926525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ModelLing of particulate matter fate on urban highway sto rmwater control systems","authors":"M. Marchioni, A. Raimondi, U. Sanfilippo, J. Sansalone, S. Mambretti, G. Becciu","doi":"10.2495/CMEM-V9-N1-1-13","DOIUrl":"https://doi.org/10.2495/CMEM-V9-N1-1-13","url":null,"abstract":"Anthropogenic activities, especially vehicular traffic, produce load of pollutants that accumulate on impervious surfaces. In highways, exhaust, automobile parts wear and lubricating parts along with heavy metals and other pollutants accumulated on the pavement surface during dry periods are the sources of pollution. Rainfall-runoff process promotes surface wash-off, contributing to stormwater pollutants’ load. The cumulative load in runoff is normally expressed as an exponential model with a peak concentration at the beginning of the rainfall event known as the first flush, where most part of the load is washed off at the beginning of the event reaching an early peak. This consideration motivates often the use of a first flush storage tank (FFT) to treat stormwater discharge from highways that is then discharged into water courses without any other treatment. It is considered that the FFT would retain the most polluted part of the runoff; however, a weak first flush is observed in some rainfall events, especially for low flow rates. Also, the vehicular traffic occurring during the rainfall event serves as a continuous source. Therefore, the objective of this research is to compare the efficiency on particle removal of an FFT with other methods of stormwater treatment, in this case an infiltration–exfiltration system (IES) consisting of a gravel swale with porous asphalt surface, through hydrological modelling of six rainfall events measured on a highway in Cincinnati (USA). The results showed a compatible removal rate for both the FFT and IES for the six analysed events, consisting of three mass-limit events and three flow-limit events. Particle transport modelling could represent well the behaviour of the events and can be used as a tool to choose between systems, where after setting the particle removal efficiency, other factors can be considered, like cost and system area consumption. This research can be followed up with continuous rainfall simulations and using computational fluid dynamics (CFD) to model IES particle removal.","PeriodicalId":22520,"journal":{"name":"THE INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS AND EXPERIMENTAL MEASUREMENTS","volume":"47 7","pages":"1-13"},"PeriodicalIF":0.0,"publicationDate":"2021-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91399685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Generalized finite difference method for anomalous diffusion on surfaces","authors":"Zhuochao Tang, Zhuojia Fu","doi":"10.2495/CMEM-V9-N1-63-73","DOIUrl":"https://doi.org/10.2495/CMEM-V9-N1-63-73","url":null,"abstract":"In this study, a localized collocation method called generalized finite difference method (GFDM) is developed to solve the anomalous diffusion problems on surfaces. The expressions of the surface Laplace operator, surface gradient operator and surface divergence operator in tangent space are given explicitly, which is different from the definition of differential operators in the Euclidean space. Based on the moving least square theorem and Taylor series, GFDM shares similar properties with standard FDM and avoids mesh dependence, enabling numerical approximations of the surface operators on complex 3D surfaces. Simultaneously, a standard finite difference scheme is adopted to discretize the time fractional derivatives. By using GFDM, we succeed in solving both constantand variableorder time fractional diffusion models on surfaces. Numerical examples show that the present meshless scheme has good accuracy and efficiency for various fractional diffusion models.","PeriodicalId":22520,"journal":{"name":"THE INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS AND EXPERIMENTAL MEASUREMENTS","volume":"66 1","pages":"63-73"},"PeriodicalIF":0.0,"publicationDate":"2021-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83250236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of load test conditions for rail fa stenings of a floating slab track","authors":"S. Tamagawa","doi":"10.2495/CMEM-V9-N1-14-27","DOIUrl":"https://doi.org/10.2495/CMEM-V9-N1-14-27","url":null,"abstract":"In Japan, rail fastenings are required to be checked for their performance by the static loading test. The test is generally performed in the laboratory under the biaxial static loading conditions. The values of the loads and loading angles are determined by using the FEM model of the track. The author has developed the FEM model of a general slab track to determine the loads and loading angles for the laboratory test of rail fastenings. However, the conventional FEM model cannot be applied to the floating slab track. Therefore, in this study, the author has developed a FEM model of the floating slab track and proposes the determination method of load conditions based on a FEM analysis. Results showed that the determination method based on the FEM model can evaluate the performance of rail fastenings of the floating slab track with a higher accuracy than before.","PeriodicalId":22520,"journal":{"name":"THE INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS AND EXPERIMENTAL MEASUREMENTS","volume":"12 1","pages":"14-27"},"PeriodicalIF":0.0,"publicationDate":"2021-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80024321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new adjoint problem for two-dimensional helmholtz equation to calculate topological derivatives of the objective functional having tangential derivative quantities","authors":"Peijun Tang, Toshiro Matsumoto, H. Isakari, Toru Takahashi","doi":"10.2495/CMEM-V9-N1-74-82","DOIUrl":"https://doi.org/10.2495/CMEM-V9-N1-74-82","url":null,"abstract":"A special topology optimization problem is considered whose objective functional consists of tangential derivative of the potential on the boundary for two-dimensional Helmholtz equation. In order to derive the adjoint problem, the functional of the conventional topology optimizations required a boundary integral of the potential and its flux. For the present objective functional having the tangential derivative, integration by parts is applied to the part having the tangential derivative of the variation of the potential to generate a tractable adjoint problem. The derived adjoint problem is used in the variation of the objective function, and the topological derivative is derived in the conventional expression.","PeriodicalId":22520,"journal":{"name":"THE INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS AND EXPERIMENTAL MEASUREMENTS","volume":"341 1","pages":"74-82"},"PeriodicalIF":0.0,"publicationDate":"2021-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77669157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"BEM analysis of gravitational–capillarity waves on free surfaces of compound shells of revolution","authors":"V. Gnitko, Artem Karaiev, M. Myronenko, E. Strelnikova","doi":"10.2495/CMEM-V9-N1-38-50","DOIUrl":"https://doi.org/10.2495/CMEM-V9-N1-38-50","url":null,"abstract":"The paper presents a problem of gravitational–capillarity wave propagation in the frame of boundary integral equations. The wave propagation is considered in rigid compound shells of revolution. The liquid is supposed to be an ideal and incompressible one, and its flow is irrotational. The boundary value problem is formulated for Laplace’s equation to obtain the velocity potential. Non-penetration boundary conditions are used at the shell’s wetted surface, as well as kinematic and dynamic boundary conditions are given on the free liquid surface. Effects of surface tension are included in the Bernoulli’s equation as additional pressure that is proportional to the free surface mean curvature. It allows us to consider coupled effects of both gravitational and capillarity waves. The problem is reduced to a system of singular integral equations. For their numerical simulation, the boundary element method is in use. The singular integral equations in implementation of a discrete model are transformed to linear algebraic ones, and eigenvalue problems are solved for different capillarity length numbers. Benchmark numerical investigations are presented including different kinds of compound rigid shells.","PeriodicalId":22520,"journal":{"name":"THE INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS AND EXPERIMENTAL MEASUREMENTS","volume":"34 1","pages":"38-50"},"PeriodicalIF":0.0,"publicationDate":"2021-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81415493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling the positive feedback mechanism of a karst aquifer using surface reconstruction","authors":"Kyffin K. Bradshaw, T. S. Ray","doi":"10.2495/cmem-v8-n4-367-386","DOIUrl":"https://doi.org/10.2495/cmem-v8-n4-367-386","url":null,"abstract":"Karst conduit network modelling is particularly difficult because the location of the conduits within an aquifer is often unknown. To address this, many mathematical models of karst aquifers use stochastically simulated conduit networks to try to extract certain geometrical and hydraulic connectivity properties that may prevail within the aquifer. Such idealized representations of a karst aquifer do not adequately represent the positive feedback mechanism that exists between the distribution of hydraulic head and the growth of the solution conduits that determine the geometry and the interconnectedness of the resulting conduit network. In this paper, Poisson surface reconstruction is presented as a simple method for constructing a realistic model of a karst aquifer by simulating the positive feedback mechanism between dissolution and flow. Direct application of the Poisson technique to a tropical karst limestone aquifer of the island of Barbados highlights how the complete conduit geometry and the feedback mechanism of a real aquifer system may be interpolated. The result suggests that applying surface reconstruction to a good calibrated point cloud sampling taken from an aquifer itself is an efficient methodology for generating realistic karstic networks. Additionally, Poisson surface reconstruction replicates an aquifer without directly solving complex hydrogeological and speleological equations and oversimplifying the hydrogeological and geological complexities of a karst environment in the way that hypothesized conduit network models do. As a result, it is believed that this conceptual model provides a utility for characterizing a karst aquifer in terms of the well-established theoretical foundations of the surface reconstruction problem even when the input data is sparse.","PeriodicalId":22520,"journal":{"name":"THE INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS AND EXPERIMENTAL MEASUREMENTS","volume":"87 1","pages":"367-386"},"PeriodicalIF":0.0,"publicationDate":"2020-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82655613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical and experimental analysis of turbulent fluid flow around latest generation cycling frame","authors":"M. Castellini, M. Barbanera, M. Scungio, F. Arpino","doi":"10.2495/cmem-v8-n4-355-366","DOIUrl":"https://doi.org/10.2495/cmem-v8-n4-355-366","url":null,"abstract":"Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyse and solve problems that involve fluid flows. Today, CFD plays a decisive role in the cycling industry, which affects not only bicycle manufacturers, but also, above all, bicycle component suppliers. In fact, aerodynamic research takes place not only in the cyclist’s best riding position, but also in the design of the components and frames that make up a racing bike. The frame design is essential both for its ability to oppose the aerodynamic resistance and to adapt the cyclist to the best geometry. Among the multiple outlets of the method, the simulation of external aerodynamic flows shows a fundamental importance for the understanding of the role played by the design of the bicycle. Once a numerical analysis was set correctly, it was then possible to predict with good reliability the fluid dynamic behaviour of an entire structure without the need to use experimental approaches every time. The main aim of this study consists of the validation of a numerical model through experiments conducted on a scale model of a latest generation cycling frame in an open chamber wind tunnel by means of the Particle Image Velocimetry (PIV) technique. In particular, the scale model used was investigated in two specific regions. The experimental data were compared to numerical results obtained employing turbulence model, and the validated numerical tool was subsequently applied to estimate the drag coefficient of two different types of handlebars (aerodynamic and standard versions). The standard cylindrical handlebar folds were replaced by products made of composite and with the most innovative and modern shapes, able to significantly reduce the aerodynamic resistance values. Indeed, in the design phase, the measurement of the drag coefficient is a fundamental procedure. As expected, the presence of aerodynamic profiles generated a low drag coefficient, one of the most important aerodynamic conditions.","PeriodicalId":22520,"journal":{"name":"THE INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS AND EXPERIMENTAL MEASUREMENTS","volume":"92 1","pages":"355-366"},"PeriodicalIF":0.0,"publicationDate":"2020-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80879876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical investigation of the interactions between a low-hypersonic shock wave and a water droplet: VOF and DI methods comparison","authors":"G. Tymen, D. Hébert, J. Rullier, T. Bridel-Bertomeu, I. Bertron, S. Peluchon, E. Lescoute, F. Virot","doi":"10.2495/cmem-v8-n4-341-354","DOIUrl":"https://doi.org/10.2495/cmem-v8-n4-341-354","url":null,"abstract":"In this paper, we present the hydrodynamic mechanisms which occur between a low-hypersonic shock wave and a millimetric water droplet. To do so, two numerical models, based respectively on the Volume of Fluid (VOF) and Diffuse Interfaces (DI) approaches, are developed. The goal is to compare the results obtained with the models in order to evaluate which is the most accurate to describe the evolution of the physical phenomena. The studied Mach number and initial droplet diameter are 4.25 and 1.135 mm, respectively. Each model allows the compressible Euler equations to be solved in a 2D-axisymmetric configuration. The evolution of both air and liquid phases is modelled by a stiffened gas equation of state. For qualitative validation, the numerical results are compared to experimental data recently presented in the literature. In this work, the authors used a shock tube test facility and a shadowgraph visualization technique to observe the phenomenology over a long time. Their investigation shows that the droplet deformation, detached bow shock and recompression waves are well captured by the two models until a Rayleigh dimensionless time of 1.5. Beyond this critical time, and up to 3, some differences appear between the two numerical approaches, especially on the droplet deformation. Globally, the droplet deformation is better described with the VOF model, while the DI model appears to be more accurate when it comes to the evaluation of the position of the bow shock. In the discussion section, some ideas are proposed to improve the models.","PeriodicalId":22520,"journal":{"name":"THE INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS AND EXPERIMENTAL MEASUREMENTS","volume":"64 1","pages":"341-354"},"PeriodicalIF":0.0,"publicationDate":"2020-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84230522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}