Articoli di riviste: "Immersed structures"

1

Iguchi, T., T. Sugaya e Y. Kawano. "Silicon-immersed terahertz plasmonic structures". Applied Physics Letters 110, n. 15 (10 aprile 2017): 151105. http://dx.doi.org/10.1063/1.4980018.

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Griffith, Boyce E., e Neelesh A. Patankar. "Immersed Methods for Fluid–Structure Interaction". Annual Review of Fluid Mechanics 52, n. 1 (5 gennaio 2020): 421–48. http://dx.doi.org/10.1146/annurev-fluid-010719-060228.

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Fluid–structure interaction is ubiquitous in nature and occurs at all biological scales. Immersed methods provide mathematical and computational frameworks for modeling fluid–structure systems. These methods, which typically use an Eulerian description of the fluid and a Lagrangian description of the structure, can treat thin immersed boundaries and volumetric bodies, and they can model structures that are flexible or rigid or that move with prescribed deformational kinematics. Immersed formulations do not require body-fitted discretizations and thereby avoid the frequent grid regeneration that can otherwise be required for models involving large deformations and displacements. This article reviews immersed methods for both elastic structures and structures with prescribed kinematics. It considers formulations using integral operators to connect the Eulerian and Lagrangian frames and methods that directly apply jump conditions along fluid–structure interfaces. Benchmark problems demonstrate the effectiveness of these methods, and selected applications at Reynolds numbers up to approximately 20,000 highlight their impact in biological and biomedical modeling and simulation.

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Strychalski, Wanda, e Robert D. Guy. "Viscoelastic Immersed Boundary Methods for Zero Reynolds Number Flow". Communications in Computational Physics 12, n. 2 (agosto 2012): 462–78. http://dx.doi.org/10.4208/cicp.050211.090811s.

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AbstractThe immersed boundary method has been extensively used to simulate the motion of elastic structures immersed in a viscous fluid. For some applications, such as modeling biological materials, capturing internal boundary viscosity is important. We present numerical methods for simulating Kelvin-Voigt and standard linear viscoelastic structures immersed in zero Reynolds number flow. We find that the explicit time immersed boundary update is unconditionally unstable above a critical boundary to fluid viscosity ratio for a Kelvin-Voigt material. We also show there is a severe time step restriction when simulating a standard linear boundary with a small relaxation time scale using the same explicit update. A stable implicit method is presented to overcome these computation challenges.

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Ju, Liehong, Peng Li e Ji hau Yang. "EXPERIMENTAL RESEARCH ON COEFFICIENT OF WAVE TRANSMISSION THROUGH IMMERSED VERTICAL BARRIER OF OPEN-TYPE BREAKWATER". Coastal Engineering Proceedings 1, n. 32 (29 gennaio 2011): 55. http://dx.doi.org/10.9753/icce.v32.structures.55.

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Extensive researches have been done for the interaction between open-type pile foundation structure and waves, including uplift force of wharf deck, horizontal force of structure and wave transmission behind breakwaters, among which wave transmission is mainly discussed in this paper. The wave transmission through a single immersed vertical barrier is analyzed by use of the physical model experiment; and an approximate formula to calculate the coefficient of wave transmission through a barrier is presented. Finally the wave damping effect of twin barriers is tested and analyzed.

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Cao, Shuai, Chun Hua Xu, Ya Bo Huang, Min Liu, Zi Hao Guo, Bo Wen Cheng, Hai Yang Duan, Lin Ge Han, Ya Nan Fan e Yu Fei You. "Wetting Property of Cu-Doped ZnO with Micro-/Nano-Structures". Advanced Materials Research 960-961 (giugno 2014): 61–64. http://dx.doi.org/10.4028/www.scientific.net/amr.960-961.61.

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ZnO with different morphologies were formed on Zn foils immersed in various concentrations of CuSO4 solutions. Then the specimens were heated at temperature of 200~600°C in air for 3h. The morphologies of as-prepared specimens were characterized by a scanning electron microscope (SEM). Water wetting angles on the specimens were measured. The results indicate that the morphologies of ZnO on the Zn foils relate to the CuSO4 concentration of in solutions. The morphologies on the specimens with dual-scale (nanoand micro) structure have higher wetting angles than those with flat structure. The water wetting angles can reduce with the increase in annealing temperatures of immersed specimens. The water wetting angles increase with keeping immersed specimens at room temperatures. The change of the wetting angle is explained by absorption of organic carbon on specimen surface and the geometric structure of the surface.

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Clark, Joseph A., Paul M. Honke e J. Michael Ellis. "Holographic measurement of power flow in large immersed structures". Journal of the Acoustical Society of America 89, n. 4B (aprile 1991): 1977. http://dx.doi.org/10.1121/1.2029748.

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Boilevin-Kayl, Ludovic, Miguel A. Fernández e Jean-Frédéric Gerbeau. "Numerical methods for immersed FSI with thin-walled structures". Computers & Fluids 179 (gennaio 2019): 744–63. http://dx.doi.org/10.1016/j.compfluid.2018.05.024.

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Binder, G. "Research on protective coating systems for immersed steel structures". Materials and Corrosion 52, n. 4 (aprile 2001): 261–67. http://dx.doi.org/10.1002/1521-4176(200104)52:4<261::aid-maco261>3.0.co;2-3.

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MEGE, Romain. "ICONE19-43307 Analytical solutions for the study of immersed unanchored structures under seismic loading". Proceedings of the International Conference on Nuclear Engineering (ICONE) 2011.19 (2011): _ICONE1943. http://dx.doi.org/10.1299/jsmeicone.2011.19._icone1943_137.

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Uhlig, Manuel R., Simone Benaglia, Ravindra Thakkar, Jeffrey Comer e Ricardo Garcia. "Atomically resolved interfacial water structures on crystalline hydrophilic and hydrophobic surfaces". Nanoscale 13, n. 10 (2021): 5275–83. http://dx.doi.org/10.1039/d1nr00351h.

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Santos, Maria Angela Vaz dos, e Armando Miguel Awruch. "Numerical Analysis of Compressible Fluids and Elastic Structures Interaction". Applied Mechanics Reviews 48, n. 11S (1 novembre 1995): S195—S202. http://dx.doi.org/10.1115/1.3005071.

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A finite element algorithm to simulate two dimensional flows of viscous and inviscid compressible fluids for a wide range of Mach numbers is presented in this work. This model is coupled to immersed deformable structures through equilibrium and compatibility conditions in order to analyze its dynamic behavior. For the fluid, time integration is performed by a two-step Taylor-Galerkin explicit scheme and Newmark’s method is used to obtain the dynamic response of the structure. An arbitrary mixed Euler-Lagrange description is used to re-define a new finite element mesh in the presence of the immersed structure displacements. Finally, several examples are included showing the model behavior and possibilities for future expansions.

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Hao, Jian, Zhilin Li e Sharon R. Lubkin. "An augmented immersed interface method for moving structures with mass". Discrete & Continuous Dynamical Systems - B 17, n. 4 (2012): 1175–84. http://dx.doi.org/10.3934/dcdsb.2012.17.1175.

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Batista, Elismar, Levi Adriano e Willian Tokura. "Gradient Einstein-type structures immersed into a Riemannian warped product". Journal of Geometry and Physics 176 (giugno 2022): 104510. http://dx.doi.org/10.1016/j.geomphys.2022.104510.

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Goza, Andres, e Tim Colonius. "A strongly-coupled immersed-boundary formulation for thin elastic structures". Journal of Computational Physics 336 (maggio 2017): 401–11. http://dx.doi.org/10.1016/j.jcp.2017.02.027.

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Viré, A., J. Xiang e C. C. Pain. "An immersed-shell method for modelling fluid–structure interactions". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, n. 2035 (28 febbraio 2015): 20140085. http://dx.doi.org/10.1098/rsta.2014.0085.

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The paper presents a novel method for numerically modelling fluid–structure interactions. The method consists of solving the fluid-dynamics equations on an extended domain, where the computational mesh covers both fluid and solid structures. The fluid and solid velocities are relaxed to one another through a penalty force. The latter acts on a thin shell surrounding the solid structures. Additionally, the shell is represented on the extended domain by a non-zero shell-concentration field, which is obtained by conservatively mapping the shell mesh onto the extended mesh. The paper outlines the theory underpinning this novel method, referred to as the immersed-shell approach. It also shows how the coupling between a fluid- and a structural-dynamics solver is achieved. At this stage, results are shown for cases of fundamental interest.

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Huang, Hongyuan, Yao Rong, Xiao Xiao e Bin Xu. "Vibration Characteristics Analysis of Immersed Tunnel Structures Based on a Viscoelastic Beam Model Embedded in a Fluid-Saturated Soil System Due to a Moving Load". Applied Sciences 13, n. 18 (14 settembre 2023): 10319. http://dx.doi.org/10.3390/app131810319.

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This study aims to investigate the vibration responses on underwater immersed tunnels caused by moving loads, taking into account factors such as the viscoelastic characteristics of riverbed water, foundation soil, and the immersed tunnel itself. An ideal fluid medium is adopted to simulate the water, while a saturated porous medium is used to simulate the riverbed soil layer. The immersed tunnel structure is simplified as an infinitely long viscoelastic Euler beam, and the vibration effects are described by the theory of the standard linear solid model, taking into account structural damping. The coupled dynamic control equations were established by utilizing the displacement and stress conditions at the interface between the ideal fluid medium, the saturated porous medium, and the immersed tunnel structure. The equivalent stiffness of the riverbed water and site foundation was obtained. Furthermore, the numerical solutions of the tunnel displacement, internal forces, and pore pressure in the riverbed site were obtained in the time-space domain using the IFFT (Inverse Fast Fourier Transform) algorithm. The correctness of the model was validated by comparing the results with existing studies. The numerical results show that the riverbed water significantly reduces the Rayleigh wave velocity of the immersed tunnel structure in the riverbed-foundation system. Therefore, it is necessary to control the driving speed during high water levels. As the permeability of the saturated riverbed foundation increases, the vertical displacement, bending moment, and shear force of the beam in the immersed tunnel structure will increase. As the viscosity coefficient of the viscoelastic beam in the immersed tunnel structure increases, the vertical vibration amplitude of the beam will decrease, but further increasing the viscosity coefficient of the beam will have little effect on its vibration amplitude. Therefore, the standard solid model of the viscoelastic beam can effectively describe the creep and relaxation phenomena of materials and can objectively reflect the working conditions of the concrete structure of the immersed tunnel.

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Sidibe, Y., F. Druaux, D. Lefebvre, F. Leon e G. Maze. "A Noncontact Method for the Detection and Diagnosis of Surface Damage in Immersed Structures". Advances in Acoustics and Vibration 2015 (19 maggio 2015): 1–10. http://dx.doi.org/10.1155/2015/429749.

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Detection and diagnosis method is proposed for surface damage in immersed structures. It is based on noncontact ultrasonic echography measurements, signal processing tools, and artificial intelligence methods. Significant features are extracted from the measured signals and a classification method is developed to detect the echoes resulting from surface damage in an immersed structure. The identification of the damage is also provided. Gaussian neural networks trained with a specific learning algorithm are developed for this purpose. The performance of the method is validated by laboratory experiments which indicate that this method could be suitable for the monitoring of inaccessible systems like marine turbines whose unavailability causes severe economic losses.

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Lee, Kwang-Ho, e Do-Sam Kim. "Development of Simplified Immersed Boundary Method for Analysis of Movable Structures". Journal of Korean Society of Coastal and Ocean Engineers 33, n. 3 (30 giugno 2021): 93–100. http://dx.doi.org/10.9765/kscoe.2021.33.3.93.

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Cao, Yong, Yuchuan Chu, Xiaoshi Zhang e Xu Zhang. "Immersed finite element methods for unbounded interface problems with periodic structures". Journal of Computational and Applied Mathematics 307 (dicembre 2016): 72–81. http://dx.doi.org/10.1016/j.cam.2016.04.020.

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YAJIMA, Shoji, Jiro FUNAKI e Katsuya HIRATA. "1659 Basic Flow Structures around a Washer Immersed in Uniform Flow". Proceedings of the JSME annual meeting 2007.2 (2007): 305–6. http://dx.doi.org/10.1299/jsmemecjo.2007.2.0_305.

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21

Fauci, Lisa J., e Aaron L. Fogelson. "Truncated newton methods and the modeling of complex immersed elastic structures". Communications on Pure and Applied Mathematics 46, n. 6 (luglio 1993): 787–818. http://dx.doi.org/10.1002/cpa.3160460602.

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Sitnikova, N. L., O. E. Philippova e E. S. Obolonkova. "Kinetically frozen structures in polymer gels immersed in a poor solvent". Macromolecular Symposia 160, n. 1 (ottobre 2000): 175–82. http://dx.doi.org/10.1002/1521-3900(200010)160:1<175::aid-masy175>3.0.co;2-u.

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Timalsina, Asim, Gene Hou e Jin Wang. "Computing Fluid-Structure Interaction by the Partitioned Approach with Direct Forcing". Communications in Computational Physics 21, n. 1 (5 dicembre 2016): 182–210. http://dx.doi.org/10.4208/cicp.080815.090516a.

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AbstractIn this paper, we propose a new partitioned approach to compute fluid-structure interaction (FSI) by extending the original direct-forcing technique and integrating it with the immersed boundary method. The fluid and structural equations are calculated separately via their respective disciplinary algorithms, with the fluid motion solved by the immersed boundary method on a uniform Cartesian mesh and the structural motion solved by a finite element method, and their solution data only communicate at the fluid-structure interface. This computational framework is capable of handling FSI problems with sophisticated structures described by detailed constitutive laws. The proposed methods are thoroughly tested through numerical simulations involving viscous fluid flow interacting with rigid, elastic solid, and elastic thin-walled structures.

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Lu, Hongduo, Samuel Stenberg, Clifford E. Woodward e Jan Forsman. "Structural transitions at electrodes, immersed in simple ionic liquid models". Soft Matter 17, n. 14 (2021): 3876–85. http://dx.doi.org/10.1039/d0sm02167a.

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We used a recently developed classical Density Functional Theory (DFT) method to study the structures, phase transitions, and electrochemical behaviours of two coarse-grained ionic fluid models, in the presence of a perfectly conducting model electrode.

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ZHANG, ZHI-QIAN, JIANYAO YAO e G. R. LIU. "AN IMMERSED SMOOTHED FINITE ELEMENT METHOD FOR FLUID–STRUCTURE INTERACTION PROBLEMS". International Journal of Computational Methods 08, n. 04 (20 novembre 2011): 747–57. http://dx.doi.org/10.1142/s0219876211002794.

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A novel procedure, immersed smoothed finite element method (immersed S-FEM) is proposed for solving fluid–structure interaction (FSI) problems with moving nonlinear solids, using triangular type of mesh. The method consists of well-combined three ingredients: two-step Taylor-characteristic-based-Galerkin (TCBG) method for incompressible viscous Navier–Stokes flows, the S-FEM for explicit dynamics analysis of nonlinear solids and structures, and FSI conditions using immersed technique with a modified direct force evaluation technique. Such a combination is designed for ensuring stability, best possible efficiency, and simplicity and convenient to use. The proposed method is verified by numerical examples using triangular meshes, which demonstrate the validity, accuracy, and the second-order convergence properties of the present method in both space and time.

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Syed Nuzul Fadzli, S. A., S. Roslinda e Firuz Zainuddin. "Sol Gel Synthesis and In Vitro Evaluation of Apatite Forming Ability of Silica-Based Composite Glass in SBF". Key Engineering Materials 660 (agosto 2015): 125–31. http://dx.doi.org/10.4028/www.scientific.net/kem.660.125.

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In this study, xerogel glass based on SiO-CaO-PO4 was synthesized by a low temperature acid catalysed sol-gel route. The in vitro evaluation of apatite forming ability for the glass was conducted in simulated body fluid (SBF) solution as the glasses were immersed for duration of 1, 7, 24 hours and 7 days. The XRD analysis showed that the glass formed semi-crystalline structure when sintered at 1000oC and consisted of Ca2O7P2 and Ca2O4Si phases. Image captured using FESEM showed the apatite-like structures were eventually formed on the glass top surface in small numbers after the glass immersed in SBF for only an hour. The numbers of the apatite structures were continuously grown with the increase period of immersion time. The apatite structure mostly covered on top of the glass surface after 24 hours of immersion and continuously growth into bone-like apatite structure when immersed for 7 days in the SBF. The apatite layer formed on the surface of the glass was confirmed as crystalline structure of hydroxyl-carbonate-apatite (HCA) as revealed by the complimentary results of EDS, XRD and FTIR analysis.

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Rizzo, Piervincenzo, Jian-Gang Han e Xiang-Lei Ni. "Structural Health Monitoring of Immersed Structures by Means of Guided Ultrasonic Waves". Journal of Intelligent Material Systems and Structures 21, n. 14 (settembre 2010): 1397–407. http://dx.doi.org/10.1177/1045389x10384170.

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Norouzi, Hamid R., Maryam Tahmasebpoor, Reza Zarghami e Navid Mostoufi. "Multi-scale analysis of flow structures in fluidized beds with immersed tubes". Particuology 21 (agosto 2015): 99–106. http://dx.doi.org/10.1016/j.partic.2015.01.005.

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Mege, Romain. "Pseudo-analytical model for sliding immersed structures under time-history earthquake loadings". Bulletin of Earthquake Engineering 15, n. 3 (23 agosto 2016): 1297–318. http://dx.doi.org/10.1007/s10518-016-9990-8.

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Zhu, Yao-Yu, Shen-You Song, Wei Liu, Ya-Wei Guo, Li Zhu e Jia-Xin Li. "Experimental and Numerical Investigation of the Cross-Sectional Mechanical Behavior of a Steel–Concrete Immersed Tube Tunnel". Buildings 12, n. 10 (28 settembre 2022): 1553. http://dx.doi.org/10.3390/buildings12101553.

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This paper presents a proposed static test and numerical study on the mechanical properties of steel-shell–concrete-structure-immersed tunnel nodes, which is used to investigate the seismic performance and damage mechanism of steel-shell–concrete-structure-immersed tunnel nodes. The test is based on the immersed tube tunnel project in the deep China channel, and the nodes representing the outermost and innermost vertical walls of the immersed tube tunnel, i.e., L-shaped and T-shaped node specimens, were designed and fabricated at a scale of 1:5, and the specimens were mainly subjected to the combined effect of vertical axial compression and lateral displacement loads. The test results show that the L-shaped node will exhibit brittle damage characteristics with high lateral load carrying capacity and energy dissipation capacity during the ultimate load phase, while the T-shaped node exhibits bending damage with better ductility, so the outermost vertical wall should be locally reinforced to ensure the necessary ductility of the structure in the actual project. In addition, by comparing the numerical calculation and experimental results, it is found that there is good agreement in terms of load–displacement curves and crack distribution, which shows that the modeling method proposed in this paper can accurately simulate the mechanical properties of immersed tunnel nodes and can guide the section design of immersed tunnels with steel shell–concrete structures.

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Zhou, Xiaojie, Qinghua Liang, Yueyu Zhang, Zhongxian Liu e Ying He. "Three-Dimensional Nonlinear Seismic Response of Immersed Tunnel in Horizontally Layered Site under Obliquely Incident SV Waves". Shock and Vibration 2019 (24 luglio 2019): 1–17. http://dx.doi.org/10.1155/2019/3131502.

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A three-dimensional (3D) detailed numerical model of an immersed tunnel in a horizontally layered site is established in this study. The 3D seismic response of the immersed tunnel in a horizontally layered site subjected to obliquely incident waves is analyzed based on the precise dynamic stiffness matrix of the soil layer and half-space via combined viscous-spring boundary and equivalent node stress methods. The nonlinear effects of external and internal site conditions on the whole model were determined by equivalent linearization algorithm and Mohr–Coulomb model, respectively. The proposed model was then applied to investigate the nonlinear seismic response of an immersed tunnel in the Haihe River subjected to seismic waves of oblique incidence. The dislocation (opening) of pipe joints in the immersed tunnel were analyzed to determine the response characteristics of the shear keys and overall displacement of the tunnel; the dynamic responses of the immersed tunnel subjected to obliquely incident seismic waves markedly differ from those of vertically incident seismic SV waves. The maximum stress value of shear keys and the maximum dislocation of the pipe joint appear as upon critical angle. The overall displacement of the tunnel increases as incident angle increases. Under severe earthquake conditions, both the pipe corners and midspan section of the roof and floor are likely to produce crack. These areas need careful consideration in the seismic design of immersed tunnel structures.

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Wang, Sheldon. "A Revisit of Implicit Monolithic Algorithms for Compressible Solids Immersed Inside a Compressible Liquid". Fluids 6, n. 8 (3 agosto 2021): 273. http://dx.doi.org/10.3390/fluids6080273.

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With the development of mature Computational Fluid Dynamics (CFD) tools for fluids (air and liquid) and Finite Element Methods (FEM) for solids and structures, many approaches have been proposed to tackle the so-called Fluid–Structure Interaction or Fluid–Solid Interaction (FSI) problems. Traditional partitioned iterations are often used to link available FEM codes with CFD codes in the study of FSI systems. Although these procedures are convenient, fluid mesh adjustments according to the motion and finite deformation of immersed solids or structures can be challenging or even prohibitive. Moreover, complex dynamic behaviors of coupled FSI systems are often lost in these iterative processes. In this paper, the author would like to review the so-called monolithic approaches for the solution of coupled FSI systems as a whole in the context of the immersed boundary method. In particular, the focus is on the implicit monolithic algorithm for compressible solids immersed inside a compressible liquid. Notice here the main focus of this paper is on liquid or more precisely liquid phase of water as working fluid. Using the word liquid, the author would like to emphasize the consideration of the compressibility of the fluid and the assumption of constant density and temperature. It is a common practice to assume that the pressure variations are not strong enough to alter the liquid density in any significant fashion for acoustic fluid–solid interactions problems. Although the algorithm presented in this paper is not directly applicable to aerodynamics in which the density change is significant along with its relationship with the pressure and the temperature, the author did revisit his earlier work on merging immersed boundary method concepts with a fully-fledged compressible aerodynamic code based on high-order compact scheme and energy conservative form of governing equations. In the proposed algorithm, on top of a uniform background (ghost) mesh, a fully implicit immersed method is implemented with mixed finite element methods for compressible liquid as well as immersed compressible solids with a matrix-free Newton–Krylov iterative solution scheme. In this monolithic approach, with the simple modulo function, the immersed solid or structure points can be easily located and thus the displacement projections and force distributions stipulated in the immersed boundary method can be effectively and efficiently implemented. This feature coupled with the key concept of the immersed boundary method helps to avoid topologically challenging mesh adjustments and to incorporate parallel processing commands such as Message Passing Interface (MPI) and further vectorization of the numerical operation. Once these high-performance procedures are implemented coupled with the monolithic implicit matrix-free Newton–Krylov iterative scheme with immersed methods, effective and efficient reduced order modeling techniques can then be employed to explore phase and parametric spaces. The in-house developed programs are at the moment two-dimensional. Furthermore, based on the same approach implemented in one-dimensional test example with one continuum immersed in another continuum, such monolithic implicit matrix-free Newton–Krylov iterative approach can be extended for the study of composites with deformable aggregates and matrix.

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Yuchao, Ma, Mo Juan, Yu Jinshan, Li Xiang e Zheng Zhongyuan. "Study on Sound Field Distribution Rule for Tank Structures of Large Oil-immersed Transformers". E3S Web of Conferences 233 (2021): 01021. http://dx.doi.org/10.1051/e3sconf/202123301021.

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Large oil-immersed transformers are an important part of the transmission and distribution network in power systems. Power transformers are the main noise source of substations. Because of the uneven manufacturing process, aging equipment, long-term operation, and close distance from sensitive points, the problem of transformer noise pollution has become increasingly prominent. In this paper, the transmission and analysis model is established for transformer sound waves on the interface between insulating oil and tank body according to the sound wave propagation rule in complicated medium, and the simplified acoustic simulation model is constructed for large oil-immersed transformers by simulating the vibration noise of transformer core with monopole sound source, with which, the sound field distribution rule inside and outside the transformer tank structure is obtained, and finally, the influence factors for noise distribution are given. The results of the study provide control basis for reducing transformer noise.

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Chern, Ming-Jyh, Wei-Cheng Hsu e Tzyy-Leng Horng. "Numerical Prediction of Hydrodynamic Loading on Circular Cylinder Array in Oscillatory Flow Using Direct-Forcing Immersed Boundary Method". Journal of Applied Mathematics 2012 (2012): 1–16. http://dx.doi.org/10.1155/2012/505916.

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Cylindrical structures are commonly used in offshore engineering, for example, a tension-leg platform (TLP). Prediction of hydrodynamic loadings on those cylindrical structures is one of important issues in design of those marine structures. This study aims to provide a numerical model to simulate fluid-structure interaction around the cylindrical structures and to estimate those loadings using the direct-forcing immersed boundary method. Oscillatory flows are considered to simulate the flow caused by progressive waves in shallow water. Virtual forces due to the existence of those cylindrical structures are distributed in the fluid domain in the established immersed boundary model. As a results, influence of the marine structure on the fluid flow is included in the model. Furthermore, hydrodynamic loadings exerted on the marine structure are determined by the integral of virtual forces according to Newton’s third law. A square array of four cylinders is considered as the marine structure in this study. Time histories of inline and lift coefficients are provided in the numerical study. The proposed approach can be useful for scientists and engineers who would like to understand the interaction of the oscillatory flow with the cylinder array or to estimate hydrodynamic loading on the array of cylinders.

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Valenti, Robert, Alex Brudno, Michael Bertoulin e Ian Davis. "Fort Point Channel: Concrete Immersed-Tube and Ventilation Building Design". Transportation Research Record: Journal of the Transportation Research Board 1541, n. 1 (gennaio 1996): 147–52. http://dx.doi.org/10.1177/0361198196154100119.

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The Central Artery/Third Harbor Tunnel Project in Boston, Massachusetts, is one of the largest highway projects over undertaken in the country. It requires the replacement of the existing elevated artery, I-93, with an underground tunnel extending through downtown Boston and an extension of the Massachusetts Turnpike Authority (MTA) I-90 from its existing termination at the I-93 interchange to Boston's Logan International Airport. The I-90 extension tunnels east under the existing South Station intercity and commuter railroad tracks, under historic Fort Point Channel while crossing above the 1915 twin subway tunnels, and continues through industrial South Boston with ramps surfacing in a new South Boston interchange, the heart of tremendous growth in Boston. From there the tunnel connects to the recently completed Ted Williams Tunnel harbor crossing to East Boston and Logan International Airport. The unique design challenges and solutions relating to the Fort Point Channel crossing, particularly the use of in-the-wet construction with concrete immersed-tube tunnels and the design interface to the ventilation structures, are presented. Structures required for the I-90 extension are concrete immersed tubes and jacked tunnels, as well as more conventional cut-and-cover tunnels, bridges, surface roads, and ancillary buildings. The geometric and physical restraints of the alignment initially required the placement of the ventilation building, which serves the tunnels, on a cut-and-cover tunnel transition section between the jacked tunnels and the concrete immersed tubes. Ultimately, placement of the ventilation building on the immersed tubes created a substantial cost and schedule benefit.

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Alamoudi, Ruaa A., e Sawsan T. Abu Zeid. "Effect of Irrigants on the Push-Out Bond Strength of Two Bioceramic Root Repair Materials". Materials 12, n. 12 (14 giugno 2019): 1921. http://dx.doi.org/10.3390/ma12121921.

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The purpose of this study was to compare different irrigants’ effect on two EndoSequence root repair materials’ push-out bond strength. Sixty root slices were filled either with EndoSequence premixed fast-set putty or regular-set paste, and then immersed either in sodium hypochlorite, chlorhexidine gluconate, or saline (as control) for 30 min, after which the slices were subjected to the push-out test. The surface structures were evaluated with Scanning Electron Microscopy and Fourier Transform Infrared. Fast-set putty exhibited greater displacement resistance when immersed in saline and subjected to adhesive failure mode, while regular-set paste showed greater resistance when immersed in chlorhexidine and subjected to cohesive failure mode. Infrared analysis showed changes in organic filler, and carbonate and phosphate bands after using irrigants. The lowest carbonate/phosphate ratio was found for chlorhexidine in both materials. Therefore, sodium hypochlorite reduced EndoSequence root repair materials’ displacement resistance markedly.

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37

COPOS, CALINA A., e ROBERT D. GUY. "A POROUS VISCOELASTIC MODEL FOR THE CELL CYTOSKELETON". ANZIAM Journal 59, n. 4 (aprile 2018): 472–98. http://dx.doi.org/10.1017/s1446181118000081.

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The immersed boundary method is a widely used mixed Eulerian/Lagrangian framework for simulating the motion of elastic structures immersed in viscous fluids. In this work, we consider a poroelastic immersed boundary method in which a fluid permeates a porous, elastic structure of negligible volume fraction, and extend this method to include stress relaxation of the material. The porous viscoelastic method presented here is validated for a prescribed oscillatory shear and for an expansion driven by the motion at the boundary of a circular material by comparing numerical solutions to an analytical solution of the Maxwell model for viscoelasticity. Finally, an application of the modelling framework to cell biology is provided: passage of a cell through a microfluidic channel. We demonstrate that the rheology of the cell cytoplasm is important for capturing the transit time through a narrow channel in the presence of a pressure drop in the extracellular fluid.

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38

Jaiswal, J. P., e R. H. Ojha. "Some properties of K-contact Riemannian manifolds admitting a semi-symmetric non-metric connection". Filomat 24, n. 4 (2010): 9–16. http://dx.doi.org/10.2298/fil1004009j.

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In this paper we present an investigation of differential geometric structures arising on immersed manifolds in K-contact Riemannian manifolds admitting semi-symmetric non-metric connection. Some properties of semi-symmetric non-metric connection in K-contact Riemannian manifolds are also obtained.

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39

Liao, Xin, Wenda Zhang, Jiannan Chen, Qingfeng Wang, Xiyong Wu, Sixiang Ling e Deping Guo. "Deterioration and Oxidation Characteristics of Black Shale under Immersion and Its Impact on the Strength of Concrete". Materials 13, n. 11 (31 maggio 2020): 2515. http://dx.doi.org/10.3390/ma13112515.

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Black shale, which usually contains pyrite, is easily oxidized and generates acid discharge. This acidic environment is not favorable for concrete in engineering applications and is likely to affect the durability of engineering structures. This study investigated the effect of acid discharge from the weathering of black shale on the strength of concrete under partially immersed conditions. Black shale concrete immersion tests were conducted at different immersion depths to evaluate the oxidation conduction of black shale. Water chemistry and oxidation products were monitored during and after the immersion tests. The quality and strength of the black shale and concrete specimens were obtained before and after the immersion by testing the ultrasonic wave velocity and uniaxial compressive strength. The results indicated that a lower immersion depth of black shale reveals a higher degree of oxidation, and the capillary zone in black shale is critical for black shale oxidation in terms of mass transfer. The ultrasonic velocity of the concrete showed different change patterns in the immersed and non-immersed zones. Precipitation and additional hydration enhanced the quality and entirety of the concrete (increased ultrasonic velocity) at the non-immersed or partially-immersed zones, while the dissolution of concrete was dominant in the immersed zone (decreased ultrasonic velocity) and induced a reduction of concrete quality. The compressive strength of the concrete was enhanced after immersion. The concrete strength slightly increased by 5–15%. This phenomenon is attributed to the filling of the voids by the precipitations of minerals, such as goethite and anhydrite.

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40

Junge, Michael, Dominik Brunner e Lothar Gaul. "Solution of the FE-BE Coupled Eigenvalue Problem for Immersed Ship-like Structures". Journal of The Japan Institute of Marine Engineering 46, n. 1 (2011): 15–27. http://dx.doi.org/10.5988/jime.46.15.

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41

Boustani, Jonathan, Michael F. Barad, Cetin C. Kiris e Christoph Brehm. "An immersed boundary fluid–structure interaction method for thin, highly compliant shell structures". Journal of Computational Physics 438 (agosto 2021): 110369. http://dx.doi.org/10.1016/j.jcp.2021.110369.

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42

Sartori, Michael A., e Joseph A. Clark. "Animated visualization of structural dynamics and acoustic radiation associated with immersed hull structures". Journal of the Acoustical Society of America 95, n. 5 (maggio 1994): 2903. http://dx.doi.org/10.1121/1.409278.

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43

Vashishth, Anil K., e Vishakha Gupta. "Scattering of ultrasonic waves from porous piezoelectric multilayered structures immersed in a fluid". Smart Materials and Structures 21, n. 12 (25 ottobre 2012): 125002. http://dx.doi.org/10.1088/0964-1726/21/12/125002.

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44

Grétarsson, Jón Tómas, e Ron Fedkiw. "Fully conservative leak-proof treatment of thin solid structures immersed in compressible fluids". Journal of Computational Physics 245 (luglio 2013): 160–204. http://dx.doi.org/10.1016/j.jcp.2013.02.017.

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45

Kondo, Ryota, Yoshihiro Myokai, Yasushi Obora e Hiroyuki T. Takeshita. "Surface Structures and Hydrogenation Properties of Ti–Pd Alloys Immersed in Hydrogen Peroxide". MATERIALS TRANSACTIONS 64, n. 11 (1 novembre 2023): 2615–21. http://dx.doi.org/10.2320/matertrans.mt-m2023089.

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46

Iovane, Giacomo, Hayeon Kim, Domenico Tizzano, Federico M. Mazzolani, Raffaele Landolfo, Solmoi Park, Beatrice Faggiano e H. K. Lee. "Cementitious materials with biological additive for enhanced durability in marine environment". ce/papers 6, n. 5 (settembre 2023): 251–57. http://dx.doi.org/10.1002/cepa.1992.

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AbstractConcrete structures suffer from cracking that leads to deterioration and shortening of service life. This is very critical for underwater structures, i.e., immersed bridge piles, immersed tunnel or submerged floating tunnels, which are consistently susceptible to ingress of harmful ions (chloride, sulphate and carbonate ions). Autonomous healing of concrete cracks can be beneficial to assure durability performance during the service life. In this context the paper presents a preliminary experimental activity carried out to study the self‐healing capacity of cementitious composites in marine environment. Four series of paste samples are prepared to evaluate the autonomous healing capabilities, achieved through biotic and abiotic additions. The experimental campaign is articulated in four phases, such as: specimen preparation; tests in compression; immersion in water; crack healing evaluation. The specimen performances are examined and compared in terms of mechanical strength and crack width healing over time. Results highlight the efficiency of the technology for crack healing.

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47

de Alcantara, Naasson P., Danilo C. Costa, Diego S. Guedes, Ricardo V. Sartori e Paulo S. S. Bastos. "A Non-Destructive Testing Based on Electromagnetic Measurements and Neural Networks for the Inspection of Concrete Structures". Advanced Materials Research 301-303 (luglio 2011): 597–602. http://dx.doi.org/10.4028/www.scientific.net/amr.301-303.597.

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This paper presents a new non-destructive testing (NDT) for reinforced concrete structures, in order to identify the components of their reinforcement. A time varying electromagnetic field is generated close to the structure by electromagnetic devices specially designed for this purpose. The presence of ferromagnetic materials (the steel bars of the reinforcement) immersed in the concrete disturbs the magnetic field at the surface of the structure. These field alterations are detected by sensors coils placed on the concrete surface. Variations in position and cross section (the size) of steel bars immersed in concrete originate slightly different values for the induced voltages at the coils.. The values for the induced voltages were obtained in laboratory tests, and multi-layer perceptron artificial neural networks with Levemberg-Marquardt training algorithm were used to identify the location and size of the bar. Preliminary results can be considered very good.

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48

Quintero, Ernesto J., Kathryn Busch e Ronald M. Weiner. "Spatial and Temporal Deposition of Adhesive Extracellular Polysaccharide Capsule and Fimbriae byHyphomonas Strain MHS-3". Applied and Environmental Microbiology 64, n. 4 (1 aprile 1998): 1246–55. http://dx.doi.org/10.1128/aem.64.4.1246-1255.1998.

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ABSTRACT Hyphomonas strain MHS-3, a member of a genus of primary colonizers of surfaces immersed in marine water, synthesizes two structures that mediate adhesion to solid substrata, namely, capsular exopolysaccharide and fimbriae. Specific stains, gold-labelled lectins, and monoclonal antibodies, along with transmission electron microscopy of synchronized populations, revealed that both structures are polarly and temporally expressed. The timed synthesis and placement of the fimbriae and capsule correlated with the timing and locus of MHS-3 adhesion.

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49

Manes, Costantino, e Maurizio Brocchini. "Local scour around structures and the phenomenology of turbulence". Journal of Fluid Mechanics 779 (14 agosto 2015): 309–24. http://dx.doi.org/10.1017/jfm.2015.389.

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The scaling of the scour depth of equilibrium at the base of a solid cylinder immersed within an erodible granular bed and impinged by a turbulent shear flow is investigated here, for the first time, by means of the phenomenological theory of turbulence. The proposed theory allows the derivation of a predictive formula that (i) includes all the relevant non-dimensional parameters controlling the process, and (ii) contrary to commonly employed empirical formulae, is free from scale issues. Theoretical predictions agree very well with experimental data, shed light on unresolved issues on the physics of the problem, and clarify the effects of various dimensionless parameters controlling the scouring process.

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50

Bilbao, Stefan. "Modeling impedance boundary conditions and acoustic barriers using the immersed boundary method: The three-dimensional case". Journal of the Acoustical Society of America 154, n. 2 (1 agosto 2023): 874–85. http://dx.doi.org/10.1121/10.0020635.

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One of the main challenges in time domain wave-based acoustics is the accurate simulation of both boundary conditions and barriers capable of reflecting and transmitting energy. Such scattering structures are generally of irregular geometry and characterised in terms of frequency-dependent reflectances and transittances. Conditions for numerical stability can be difficult to obtain in either case. Immersed boundary methods, which are heavily used in computational fluid dynamics applications, replace boundaries by discrete driving terms, avoiding volumetric meshing and staircasing approaches altogether. The main contribution of this article is a unified numerical treatment of both impedance boundary conditions and barriers capable of transmitting energy and suitable for use in the setting of wave-based acoustics. It is framed in terms of the immersed boundary method within a finite difference time domain scheme, using a dual set of matched discrete driving terms in both the conservation of mass and momentum equations that can be tuned against a desired reflectance or transmittance. Numerical results in three dimensions are presented, illustrating non-porous barriers and impedance boundary conditions, and highlight important features such as spurious leakage through an immersed boundary. A brief demonstration of conditions for numerical stability of the immersed boundary method in this context is provided in an appendix.

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