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Статті в журналах з теми "Phenomenological fluid-structure interaction model"
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Zakharov, V. E., and A. N. Pushkarev. "Diffusion model of interacting gravity waves on the surface of deep fluid." Nonlinear Processes in Geophysics 6, no. 1 (March 31, 1999): 1–10. http://dx.doi.org/10.5194/npg-6-1-1999.
Повний текст джерелаАнотація:
Abstract. A simple phenomenological model for nonlinear interactions of gravity waves on the surface of deep water is developed. The Snl nonlinear interaction term in the kinetic equation for wave action is replaced by the nonlinear second-order diffusion-type operator. Analytical and numerical studies show that the new model gives a reasonably good description of a real situation, consuming three order of magnitude less computer time.
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Frommater, Stefan, Jens Neumann, and Christian Hasse. "A phenomenological mixture homogenization model for spark-ignition direct-injection engines." International Journal of Engine Research 19, no. 2 (June 6, 2017): 168–78. http://dx.doi.org/10.1177/1468087417711858.
Повний текст джерелаАнотація:
In modern turbocharged direct-injection, spark-ignition engines, proper calibration of the engine control unit is essential to handle the increasing variability of actuators. The physically based simulation of engine processes such as mixture homogenization enables a model-based calibration of the engine control unit to identify an ideal set of actuator settings, for example, for efficient combustion with reduced exhaust emissions. In this work, a zero-dimensional phenomenological model for direct-injection, spark-ignition engines is presented that allows the equivalence ratio distribution function in the combustion chamber to be calculated and its development is tracked over time. The model considers the engine geometry, mixing time, charge motion and spray–charge interaction. Accompanying three-dimensional computational fluid dynamics, simulations are performed to obtain information on homogeneity at different operating conditions and to calibrate the model. The calibrated model matches the three-dimensional computational fluid dynamics reference both for the temporal homogeneity development and for the equivalence ratio distribution at the ignition time, respectively. When the model is validated outside the calibrated operating conditions, this shows satisfying results in terms of mixture homogeneity at the time of ignition. Additionally, only a slight modification of the calibration is shown to be required when transferring the model to a comparable engine. While the model is primarily aimed at target applications such as a direct-injection, spark-ignition soot emission model, its application to other issues, such as gaseous exhaust emissions, engine knock or cyclic fluctuations, is conceivable due to its general structure. The fast calculation enables mixture inhomogeneities to be estimated during driving cycle simulations.
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Bušík, Martin, Martin Slavík, and Ivan Cimrák. "Dissipative Coupling of Fluid and Immersed Objects for Modelling of Cells in Flow." Computational and Mathematical Methods in Medicine 2018 (September 27, 2018): 1–11. http://dx.doi.org/10.1155/2018/7842857.
Повний текст джерелаАнотація:
Modelling of cell flow for biomedical applications relies in many cases on the correct description of fluid-structure interaction between the cell membrane and the surrounding fluid. We analyse the coupling of the lattice-Boltzmann method for the fluid and the spring network model for the cells. We investigate the bare friction parameter of fluid-structure interaction that is mediated via dissipative coupling. Such coupling mimics the no-slip boundary condition at the interface between the fluid and object. It is an alternative method to the immersed boundary method. Here, the fluid-structure coupling is provided by forces penalising local differences between velocities of the object’s boundaries and the surrounding fluid. The method includes a phenomenological friction coefficient that determines the strength of the coupling. This work aims at determination of proper values of such friction coefficient. We derive an explicit formula for computation of this coefficient depending on the mesh density assuming a reference friction is known. We validate this formula on spherical and ellipsoidal objects. We also provide sensitivity analysis of the formula on all parameters entering the model. We conclude that such formula may be used also for objects with irregular shapes provided that the triangular mesh covering the object’s surface is in some sense uniform. Our findings are justified by two computational experiments where we simulate motion of a red blood cell in a capillary and in a shear flow. Both experiments confirm our results presented in this work.
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Perez, Marta, Emmanuelle Abisset-Chavanne, Elias Cueto, Roland Keunings, and Francisco Chinesta. "Fluid-Long Fiber Interaction Based on a Second Gradient Theory." Key Engineering Materials 651-653 (July 2015): 331–37. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.331.
Повний текст джерелаАнотація:
Most suspension descriptions nowadays employed are based on the Jeffery's model andsome phenomenological adaptations of it that do not take into account size effects, that is, the kinematicsand stresses do not introduce a micro-mechanical characteristic length and thus, the rheologicalproperties become independent of the rod length. New models able to enrich first gradient kinematicsas well as to activate rod-bending mechanisms (needed for explaining the mild elasticity experimentallynoticed) are needed. In this paper we propose a second gradient description able to activate rods bending.
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MANGANO, G., G. MIELE, and V. PETTORINO. "COUPLED QUINTESSENCE AND THE COINCIDENCE PROBLEM." Modern Physics Letters A 18, no. 12 (April 20, 2003): 831–42. http://dx.doi.org/10.1142/s0217732303009940.
Повний текст джерелаАнотація:
We consider a model of interacting cosmological constant/quintessence, where dark matter and dark energy behave as, respectively, two coexisting phases of a fluid, a thermally excited Bose component and a condensate, respectively. In a simple phenomenological model for the dark components interaction we find that their energy density evolution is strongly coupled during the universe evolution. This feature provides a possible way out for the coincidence problem affecting many quintessence models.
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Khurshudyan, M., J. Sadeghi, E. Chubaryan та H. Farahani. "Phenomenologically varying Λ and a toy model for the universe". Canadian Journal of Physics 92, № 11 (листопад 2014): 1494–500. http://dx.doi.org/10.1139/cjp-2014-0103.
Повний текст джерелаАнотація:
We consider a model of the Universe with variable G and Λ. The subject of interest is a phenomenological model for Λ proposed and considered in this article for the first time (to our knowledge), with the assumption that ghost dark energy exists and interacts with the Universe through Λ. We consider the possibility that there exist unusual connections between different components of the fluids in Universe. We would like to stress that this is simply an assumption and could be very far from reality. This model is interesting phenomenologically and mathematically but we will not discuss physical conditions or possibilities of implementing the modifications. To test our assumption and to observe the behavior of the Universe, we will consider toy models filled by a barotropic fluid and modified Chaplyagin gas. Finally, we will consider interaction between barotropic fluid or Chaplygin gas and ghost dark energy as a separate scenario. The statefinder diagnostic provided stability analysis of the models. All free parameters of the model are fixed to satisfy the generalized second law of thermodynamics.
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Gonchar, Liudmila, and Anatoliy Nikiforov. "Vibronic interaction as main reason of magnetic ordering in insulating manganites R1–xAxMnO3." EPJ Web of Conferences 185 (2018): 06005. http://dx.doi.org/10.1051/epjconf/201818506005.
Повний текст джерелаАнотація:
The model of orbitally dependent magnetic structure of charge ordered insulated manganites is proposed. The model is semi-phenomenological. It allows using a few parameters to describe possible magnetic structures of compounds. The experimental crystal structure of compounds also could be taken into account. The compounds LaMnO3, La1/2Ca1/2MnO3, La1/3Ca2/3MnO3, BiMnO3 are considered.
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Pushkarev, A., D. Resio, and V. Zakharov. "Second generation diffusion model of interacting gravity waves on the surface of deep fluid." Nonlinear Processes in Geophysics 11, no. 3 (July 27, 2004): 329–42. http://dx.doi.org/10.5194/npg-11-329-2004.
Повний текст джерелаАнотація:
Abstract. We propose a second generation phenomenological model for nonlinear interaction of gravity waves on the surface of deep water. This model takes into account the effects of non-locality of the original Hasselmann diffusion equation still preserving important properties of the first generation model: physically consistent scaling, adherence to conservation laws and the existence of Kolmogorov-Zakharov solutions. Numerical comparison of both models with the original Hasselmann equation shows that the second generation models improves the angular distribution in the evolving wave energy spectrum.
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Zhang, Ying. "A unified Yukawa interaction for the Standard Model of quarks and leptons." Modern Physics Letters A 36, no. 27 (September 7, 2021): 2150196. http://dx.doi.org/10.1142/s0217732321501960.
Повний текст джерелаАнотація:
To address fermion mass hierarchy and flavor mixings in the quark and lepton sectors, a minimal flavor structure without any redundant parameters beyond phenomenological observables is proposed via decomposition of the Standard Model Yukawa mass matrix into a bi-unitary form. After reviewing the roles and parameterization of the factorized matrix [Formula: see text] and [Formula: see text] in fermion masses and mixings, we generalize the mechanism to up- and down-type fermions to unify them into a universal quark/lepton Yukawa interaction. In the same way, a unified form of the description of the quark and lepton Yukawa interactions is also proposed, which shows a similar picture as the unification of gauge interactions.
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da Rocha, Roldão. "MGD Dirac Stars." Symmetry 12, no. 4 (April 1, 2020): 508. http://dx.doi.org/10.3390/sym12040508.
Повний текст джерелаАнотація:
The method of geometric deformation (MGD) is here employed to study compact stellar configurations, which are solutions of the effective Einstein–Dirac coupled field equations on fluid branes. Non-linear, self-interacting, fermionic fields are then employed to derive MGD Dirac stars, whose properties are analyzed and discussed. The MGD Dirac star maximal mass is shown to increase as a specific function of the spinor self-interaction coupling constant, in a realistic model involving the most strict phenomenological current bounds for the brane tension.
Дисертації з теми "Phenomenological fluid-structure interaction model"
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TEUMA-MELAGO, Eric. "A FLUID STRUCTURE INTERACTION MODEL OF INTRACORONARY ATHEROSCLEROTIC PLAQUE RUPTURE." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2359.
Повний текст джерелаАнотація:
Plaque rupture with superimposed thrombosis is the primary cause of acute coronary syndromes of unstable angina, myocardial infarction and sudden death. Although intensive studies in the past decade have shed light on the mechanism that causes unstable atheroma, none has directly addressed the clinical observation that most myocardial infarction (MI) patients have moderate stenoses (less than 50%). Considering the important role the arterial wall compliance and pulsitile blood flow play in atheroma rupture, fluid-structure interaction (FSI) phenomenon has been of interest in recent studies. In this thesis, the impact is investigated numerically of coupled blood flow and structural dynamics on coronary plaque rupture. The objective is to determine a unique index that can be used to characterize plaque rupture potential. The FSI index, developed in this study for the first time derives from the theory of buckling of thin-walled cylinder subjected to radial pressure. Several FSI indices are first defined by normalizing the predicted hemodynamic endothelial shear stress by the structural stresses, specifically, by the maximum principal stress (giving the ratio ), and the Von Mises stress (giving the ratio ). The predicted at the location of maximum (i.e { }) denoted , is then chosen to characterize plaque rupture through systematic investigation of a variety of plaque characteristics and simulated patient conditions. The conditions investigated include varying stenosis levels ranging from 20% to 70%, blood pressure drop ranging from 3125 Pa/m to 9375 Pa/m, fibrous cap thickness ranging from to , lipid pool location ranging from the leading to the trailing edge of plaque, lipid pool volume relative to stenosis volume ranging from 24% to 80%, Calcium volume relative to stenosis volume ranging from 24% to 80% and arterial remodeling. The predicted varies with the stenosis severity and indicates that the plaques investigated are prone to rupture at approximately 40-45% stenosis levels. It predicts that high pressure significantly lowers the threshold stenosis rate for plaque rupture. In addition, the plaque potential to rupture increases for relatively thin fibrous cap, lipid core located near the leading plaque shoulder, and dramatically for relative lipid pool volume above 60%. However, calcium deposit has marginal effect on plaque rupture. Overall, the predicted results are consistent with clinical observations, indicating that the has the potential to characterize plaque rupture when properly established. In the appendix, the unsteady flow in a collapsible tube model of a diseased artery is solved analytically. The novelty of our approach is that the set of governing equations is reduced to a single integro-differential equation in the transient state. The equation was solved using the finite difference method to obtain the pressure and compliant wall behavior. The analytical approach is less computer-intensive than solving the full set of governing equations. The predicted membrane deflection is quite large at low inlet velocity, suggesting possible approach to breakdown in equilibrium. As the transmural pressure increases with wall deflection, bulges appear at the ends of the membrane indicating critical stage of stability, consistent with previous studies. An increase in wall thickness reduces the wall deflection and ultimately results in its collapse. The collapse is due to breakdown in the balance of wall governing equation. An increase in internal pressure is required to maintain membrane stability.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
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Ferria, Hakim. "Experimental Campaign on a Generic Model for Fluid-Structure Interaction Studies." Thesis, KTH, Kraft- och värmeteknologi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-48975.
Повний текст джерелаАнотація:
Fluid-structure interactions appear in many industrial applications in the field of energy technology. As the components are more and more pushed to higher performance, taking fluid-structure interaction phenomena into account has a great impact on the design as well as in the cost and safety. Internal flows related to propulsion systems in aerodynamics area are of our interest; and particularly aeroelasticity and flutter phenomena. A new 2D flexible generic model, so called bump, based on previous studies at the division of Heat and Power Technology about fluid-structure interactions is here presented. The overall goal is to enhance comprehension of flutter phenomenon. The current study exposes a preliminary experimental campaign regarding mechanical behaviour on two different test objects: an existing one made of polyurethane and a new one of aluminium. The setup is built in such a way that it allows the bumps to oscillate until 500Hz. The objective is to reach this frequency range by remaining in the first bending mode shape which is indeed considered as fundamental for flutter study. In this manner being as close as possible to the bending flutter configuration in high-subsonic and transonic flows will provide a deeper understanding of the shock wave boundary layer interaction and the force phase angle related to it. The results have pointed out that the bumps can reach a frequency of 250Hz by remaining in the first bending mode shape. The one in polyurethane can even reach frequency up to 350Hz; however, amplitude is higher than the theoretical one fixed to 0.5mm. Then unsteady pressure measurements for one operating point have been performed based on using recessed-mounted pressure transducers with Kulite fast response sensors. Variation amplitudes and phases of the unsteady pressure are thus correlated with the vibrations of the model. The operating point has been defined with respect to previous studies on the same static geometric model in order to use steady state base line; the steady flows appear consistent with each other. The results have pointed out that the shock wave induces strong amplification of the steady static pressure; however, this rise decreases when the reduced frequency increases. Finally some elements regarding propagating waves are suggested in the analysis for deeper investigations on such complex phenomena.
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Hao, Qing. "Modeling of Flow in an In Vitro Aneurysm Model: A Fluid-Structure Interaction Approach." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/508.
Повний текст джерелаАнотація:
Flow velocity field, vorticity and circulation and wall shear stresses were simulated by FSI approach under conditions of pulsatile flow in a scale model of the rabbit elastin-induced aneurysm. The flow pattern inside the aneurysm sac confirmed the in vitro experimental findings that in diastole time period the flow inside the aneurysm sac is a stable circular clock-wise flow, while in systole time period higher velocity enters into the aneurysm sac and during systole and diastole time period an anti-clock circular flow pattern emerged near the distal neck; in the 3-D aneurysm sac, the kinetic energy per point is about 0.0002 (m2/s2); while in the symmetrical plane of the aneurysm sac, the kinetic energy per point is about 0.00024 (m2/s2). In one cycle, the shape of the intraaneurysmal energy profile is in agreement with the experimental data; The shear stress near the proximal neck experienced higher shear stress (peak value 0.35 Pa) than the distal neck (peak value 0.2 Pa), while in the aneurysm dome, the shear stress is always the lowest (0.0065 Pa). The ratio of shear stresses in the proximal neck vs. distal neck is around 1.75, similar to the experimental findings that the wall shear rate ratio of proximal neck vs. distal neck is 1.5 to 2.
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Venkataraman, Siddharth. "Analytic, Simulation and Experimental Analysis of Fluid-Pipe Systems." Thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-249996.
Повний текст джерелаАнотація:
Inviscid fluid inside thin pipe system is first analytically solved for eigenfrequencies and eigenmodes using Modal Interaction Model method with fluid-structure interaction condition at boundary. Shear-diaphragm boundary condition is used for comparing and validating Analytic results with Simulation using COMSOL Multiphysics. Effect of viscosity is also compared using Newtonian fluid model. Experiment is performed using simple pipe geometry and fluid to measure transfer accelerance which is post-processed to extract cirumferential modes up to order 4; this is used to compare and validate Experiemental results with Simulation. Good correlation is obtained between Analytic, Experiment and Simulation results with n=0 breathing modes requiring modification of governing equations to incorporate compressibility effects due to changing pipe cross-section area.En analytisk lösning för egenfrekvenser och egenmoder för en icke-viskös fluid inuti ett tunt rörsystem är först framtagen med användning av en modbaserad modell för interaktion mellan fluid och struktur som randvillkor. Idealiserad randvillkor används för att jämföra och validera analytiska resultat med simulationer i COMSOL Multiphysics. Effekten av viskositet jämförs också med hjälp av en Newtonsk fluidmodell. Experiment genomförs med simpel rörgeometri samt fluid för att mäta acceleransen som är analyserad för till att få ut mo-der i omkretsled upp till fjärde ordningen; detta i sin tur används för att jämföra och validera de experimentella resultaten med simulering-ar. Det erhålls bra korrelation mellan de analytiska-, simulerade- samt experimentella resultaten. Undantaget för n=0 grundmoder då krävs modifikation av differentialekvationerna till att inkorporera kompressibilitetseffekter
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Tenaud, Philippe. "Analyse expérimentale des mécanismes de coercitivité dans les aimants Nd-Fe-B frittés." Grenoble 1, 1988. http://www.theses.fr/1988GRE10092.
Повний текст джерелаАнотація:
Mise en evidence par des mesures de trainage magnetique d'une faible reduction du champ coercitif par agitation thermique. Analyse de la variation angulaire du champ coercitif et de l'anisotropie du volume d'activation. Le developpement de la coercite en fonction du champ initial de saturation sur des echantillons desaimantes thermiquement s'interprete en supposant une apparition brutale de la coercite dans chaque grain. Mise en evidence de l'influence d'effets dipolaires locaux importants. Deduction d'un modele phenomenologique de coercite. Analyse du mecanisme de renversement d'aimantation sous l'effet du champ, des interactions dipolaires et de l'agitation thermique
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VARELLO, ALBERTO. "Advanced higher-order one-dimensional models for fluid-structure interaction analysis." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2517517.
Повний текст джерелаАнотація:
The aim of this work is the development of a refined reduced order model suitable for numerical applications in solid and fluid mechanics with a remarkable reduction in computational cost. Nowadays, numerical reduced order models are widely exploited in many areas, such as aerospace, mechanical and biomechanical engineering for structural analysis, fluid dynamic analysis and coupled (aeroelastic) fluid-structure interaction analysis.
One-dimensional (1D) structural models, commonly known as beams, are for instance used in many applications to analyze the structural behavior of slender bodies, such as columns, arches, blades, aircraft wings, bridges, skyscrapers, rotor and wind turbine blades. One-dimensional structural elements are simpler and computationally more efficient than 2D (plate/shell) and 3D (solid) elements. This feature makes beam theories still very attractive for the static, dynamic response, free vibration and aeroelastic analyses, despite the approximations which they introduce in the simulation.
Recently, 1D models are intensively exploited for the simulation of the human cardiovascular system under either physiological or pathological conditions. As it is easily comprehensible, fluid flows in pipes, channel, capillaries or even arteries are particularly suitable for the application of one-dimensional models also to fluid dynamics. Typically, one-dimensional models for fluid dynamics and fluid-structure interaction (FSI) problems are again remarkably more efficient than three-dimensional methods in terms of computational cost.
A key point for reduced order models is the capability in simulating in an accurate way the investigated physical problem. For instance, in last decades the growing use of advanced composite and sandwich materials in thin-walled beam-like structures has revealed that 1D theories have to be refined in order to predict the behavior of such complex structures with high fidelity. For this purpose, a higher-order one-dimensional method is introduced in this work and its capabilities are highlighted and discussed. The present work is subdivided into three fundamental parts corresponding to the physical fields the proposed refined model is applied to.
Firstly, a structural part presents the formulation of a displacement-based higher-order one-dimensional model for the analysis of beam-like structures. Classical beam theories (Euler-Bernoulli and Timoshenko) have intrinsic limitations which preclude their applications for the analysis of a wide class of engineering problems. The Carrera Unified Formulation (CUF) is employed to introduce a hierarchical modeling with a variable order of expansion for the displacement unknowns over the beam cross-section. The finite element method (FEM) is used to handle arbitrary geometries and loading conditions. The influence of higher-order effects over the cross-section deformation, not detectable by classical and low-order beam theories, on the static, free vibration and time-dependent response of several structures with arbitrary cross-section geometries and made of arbitrary materials is remarked through the numerical results presented.
Secondly, an aeroelastic part describes the extension of the refined structural model to the static aeroelastic analysis of lifting surfaces made of metallic and composite materials. A coupled aeroelastic computational model based on the Vortex Lattice aerodynamic Method and the finite element method (FEM) is formulated. A refined aeroelastic approach is also presented by replacing the Vortex Lattice aerodynamic Method with the more powerful 3D Panel Method. Comparison with results obtained by existing plate/shell aeroelastic models shows that the present 1D model could result less expensive from the computational point of view with respect to shell cases with same accuracy. The effect of the cross-section deformation on the aeroelastic static response and on the critical wing divergence velocity is evaluated for different wing configurations. The beneficial effects of aeroelastic tailoring in the case of wings made of composite anisotropic materials are also confirmed by using the present model.
Finally, a third part concerning the use of the refined one-dimensional CUF model for fluid dynamic problems is presented. The basic partial differential equations (PDEs) of fluid mechanics (Navier-Stokes and Stokes equations) are faced and 1D refined models with variable velocity-pressure accuracy are presented on the basis of the one-dimensional Carrera Unified Formulation and the finite element method. The application of these higher-order models to describe the three-dimensional fluid flow evolution on a computational domain is formulated for the Stokes problem. The present approach reveals its capabilities in predicting accurately, with a reduced computational cost with respect to more consuming two-dimensional or three-dimensional methods, nonclassical and complex fluid flows. Moreover, the numerical results show the promising potentiality of such an approach to the future extension of fluid-structure CUF-CUF models, i.e. the coupling of CUF models used for both structural and fluid dynamic analyses.
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Mowat, Andrew Gavin Bradford. "Modelling of non-linear aeroelastic systems using a strongly coupled fluid-structure-interaction methodology." Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/30521.
Повний текст джерелаАнотація:
The purpose of this study was to develop a robust fluid-structure-interaction (FSI) technology that can accurately model non-linear flutter responses for sub- and transonic fluid flow. The Euler equation set governs the fluid domain, which was spatially discretised by a vertex-centred edge-based finite volume method. A dual-timestepping method was employed for the purpose of temporal discretisation. Three upwind schemes were compared in terms of accuracy, efficiency and robustness, viz. Roe, HLLC (Harten-Lax-Van Leer with contact) and AUSM+-up Advection Up-stream Splitting Method). For this purpose, a second order unstructured MUSCL (Monotonic Upstream-centred Scheme for Conservation Laws) scheme, with van Albada limiter, was employed. The non-linear solid domain was resolved by a quadratic modal reduced order model (ROM), which was compared to a semi-analytical and linear modal ROM. The ROM equations were solved by a fourth order Runge-Kutta method. The fluid and solid were strongly coupled in a partitioned fashion with the information being passed at solver sub-iteration level. The developed FSI technology was verified and validated by applying it to test cases found in literature. It was demonstrated that accurate results may be obtained, with the HLLC upwind scheme offering the best balance between accuracy and robustness. Further, the quadratic ROM offered significantly improved accuracy when compared to the linear method.Dissertation (MEng)--University of Pretoria, 2011.
Mechanical and Aeronautical Engineering
unrestricted
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Hosein, Falahaty. "Enhanced fully-Lagrangian particle methods for non-linear interaction between incompressible fluid and structure." Kyoto University, 2018. http://hdl.handle.net/2433/235070.
Повний текст джерела
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Lemmon, Jack David Jr. "Three-dimensional computational modeling of fluid-structure interaction : study of diastolic function in a thin-walled left heart model." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/15912.
Повний текст джерела
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BERTAGLIA, Giulia. "1D augmented fluid-structure interaction systems with viscoelasticity: from water pipelines to blood vessels." Doctoral thesis, Università degli studi di Ferrara, 2020. http://hdl.handle.net/11392/2488143.
Повний текст джерелаАнотація:
Nowadays, mathematical models and numerical simulations are widely used in the whole fluid dynamics research field. They represent a powerful resource to better understand phenomena and processes and to significantly reduce the costs that would otherwise be necessary for carrying out laboratory experiments (sometimes even allowing to obtain useful data that could not be collected by measurements).
Currently there are many important industries of hydraulic systems which, for the correct analysis of the behavior of the designed systems, require the preventive use of an accurate mathematical model, able to describe the trend of the properties of the fluid in the pipelines. On the other hand, the availability of robust and efficient mathematical instruments, together with the engineering know-how in the fluid mechanics sector, represents an invaluable tool for a consistent support even in hemodynamics studies, providing practical approaches for the quantification of variables involved in the cardiovascular fluid dynamics.
The correct characterization of the interactions occurring between the fluid and the wall that circumscribes the motion of the fluid itself, is a fundamental aspect in all the contexts involving deformable ducts, which requires the utmost attention at every stage of both the development of the computational scheme and the interpretation of the results and at their application to cases of practical interest.
In this PhD Thesis, innovative mathematical models able to predict the behavior of the fluid-structure interaction mechanism that underlies the dynamics of flows in different compliant ducts is presented. Starting from the purely civil engineering sector, with the study of plastic water pipelines, the final application of the proposed tool is linked to the medical research field, to reproduce the mechanics of blood flow in both arteries and veins. With this aim, various linear viscoelastic models, from the simplest to the more sophisticated, have been applied and extended to obtain augmented fluid-structure interaction systems in which the constitutive equation of the material is directly inserted into the system as partial differential equation. These systems are solved recurring to second-order Finite Volume Methods that take into account the recent evolution in the computational literature of hyperbolic balance laws systems. The models have been extensively validated through different types of test cases, highlighting the advantages of using the augmented formulation of the system of equations. Numerical results have been compared with quasi-exact solutions of idealized time-dependent tests for situations close to reality or with reference values obtained with numerical schemes generally adopted in the specific research field investigated. Furthermore, comparisons with experimental data have been considered both for the water pipelines scenario and the blood flow modeling, recurring to ad hoc in-vivo measurements for the latter. Accuracy and efficiency analyses have been performed in different contexts, as well as a sensitivity analysis with regards to the final part of the project, related to a more applicative study on arterial hypertension.Oggigiorno, modelli matematici e simulazioni numeriche sono ampiamente utilizzati nell’intero campo della ricerca fluidodinamica. Essi rappresentano una potente risorsa per comprendere meglio i fenomeni e i processi e per ridurre significativamente i costi che sarebbero altrimenti necessari per la realizzazione di esperimenti di laboratorio (a volte anche per ottenere utili dati che non potrebbero essere raccolti mediante misurazioni). Attualmente esistono molte importanti industrie di sistemi idraulici che, per la corretta analisi del comportamento dei sistemi progettati, richiedono l’uso preventivo di un accurato modello matematico, in grado di descrivere l’andamento delle proprietà del fluido nelle tubazioni. D’altra parte, la disponibilità di strumenti matematici robusti ed efficienti, insieme al know-how ingegneristico nel settore della fluidodinamica, rappresenta uno strumento inestimabile per un supporto costante anche negli studi emodinamici, fornendo approcci pratici per la quantificazione delle variabili coinvolte nella fluidodinamica cardiovascolare. La corretta caratterizzazione delle interazioni tra il fluido e la parete che ne circoscrive il moto, è un aspetto fondamentale in tutti i contesti di condotte deformabili, che richiede la massima attenzione in ogni fase dello sviluppo dello schema di calcolo e della interpretazione dei risultati e nella loro applicazione a casi di interesse pratico. In questa Tesi di Dottorato vengono presentati innovativi modelli matematici in grado di prevedere il comportamento del meccanismo di interazione fluido-struttura che sta alla base della dinamica dei flussi in diverse condotte deformabili. Partendo dal settore dell’ingegneria puramente civile, con lo studio di condotte idrauliche in plastica, l’applicazione finale dello strumento proposto è legata al campo della ricerca medica, per riprodurre la meccanica del flusso sanguigno sia nelle arterie che nelle vene. A tal fine, sono stati applicati ed estesi diversi modelli viscoelastici lineari, dai più semplici ai più sofisticati, per ottenere sistemi aumentati di interazione fluido-struttura in cui l’equazione costitutiva del materiale è direttamente inserita nel sistema come equazione alle derivate parziali. Questi sistemi sono risolti ricorrendo a Metodi ai Volumi Finiti al secondo ordine che tengono conto della recente evoluzione della letteratura computazionale dei sistemi iperbolici di leggi di bilancio. I modelli sono stati ampiamente validati attraverso diversi tipi di casi test, evidenziando i vantaggi dell’utilizzo del sistema di equazioni in forma aumentata. I risultati numerici sono stati confrontati con soluzioni quasi esatte di problemi ideali dipendenti dal tempo per situazioni vicine alla realtà o con valori di riferimento ottenuti con schemi numerici adottati solitamente nello specifico campo di ricerca indagato. Inoltre, sono stati presi in considerazione confronti con dati sperimentali sia per lo scenario delle condotte idriche che per la modellazione del flusso sanguigno, ricorrendo a misurazioni in-vivo ad hoc per quest’ultimo. Sono state effettuate analisi di accuratezza ed efficienza in diversi contesti, nonché un’analisi di sensitività per quanto riguarda la parte finale del progetto, relativa ad uno studio più applicativo sull’ipertensione arteriosa.
Частини книг з теми "Phenomenological fluid-structure interaction model"
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Guerra, Gabriel M., Rodolfo Freitas, and Fernando A. Rochinha. "Constructing Accurate Phenomenological Surrogate for Fluid Structure Interaction Models." In Mechanisms and Machine Science, 295–305. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99272-3_21.
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Geller, S., S. Kollmannsberger, M. El Bettah, M. Krafczyk, D. Scholz, A. Düster, and E. Rank. "An Explicit Model for Three-Dimensional Fluid-Structure Interaction using LBM and p-FEM." In Fluid Structure Interaction II, 285–325. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14206-2_11.
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Dillon, Robert H., and Lisa J. Fauci. "A Fluid-Structure Interaction Model of Ciliary Beating." In Computational Modeling in Biological Fluid Dynamics, 71–79. New York, NY: Springer New York, 2001. http://dx.doi.org/10.1007/978-1-4613-0151-6_4.
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Ballarin, Francesco, Gianluigi Rozza, and Yvon Maday. "Reduced-Order Semi-Implicit Schemes for Fluid-Structure Interaction Problems." In Model Reduction of Parametrized Systems, 149–67. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-58786-8_10.
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Hasnedlová-Prokopová, J., M. Feistauer, A. Kosík, and V. Kučera. "Two Dimensional Compressible Fluid-Structure Interaction Model Using DGFEM." In Numerical Mathematics and Advanced Applications 2011, 361–68. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-33134-3_39.
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Gajić, A., S. Pejović, and Z. Stojanović. "Hydraulic Oscillation Analysis Using the Fluid-Structure Interaction Model." In Hydraulic Machinery and Cavitation, 845–54. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-010-9385-9_86.
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Cerroni, D., D. Giommi, S. Manservisi, and F. Mengini. "Preliminary Monolithic Fluid Structure Interaction Model for Ventricle Contraction." In Biomedical Technology, 217–31. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-59548-1_12.
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Rajbamshi, Srijan, Qintao Guo, and Ming Zhan. "Model Updating of Fluid-Structure Interaction Effects on Piping System." In Conference Proceedings of the Society for Experimental Mechanics Series, 133–39. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-12184-6_12.
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Snyder, William, Changhong Mou, Honghu Liu, Omer San, Raffaella DeVita, and Traian Iliescu. "Reduced Order Model Closures: A Brief Tutorial." In Recent Advances in Mechanics and Fluid-Structure Interaction with Applications, 167–93. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-14324-3_8.
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Coskun, Umut Can, Hasan Gunes, and Kemal Sarioglu. "A Numerical Model of Fluid Structure Interaction of a Fluttering Valve." In Springer Proceedings in Physics, 421–29. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-30602-5_53.
Повний текст джерелаТези доповідей конференцій з теми "Phenomenological fluid-structure interaction model"
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Sargentini, Lucia, Benjamin Cariteau, and Morena Angelucci. "Experimental and Numerical Analysis for Fluid-Structure Interaction for an Enclosed Hexagonal Assembly." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28053.
Повний текст джерелаАнотація:
This paper is related to fluid-structure interaction analysis of sodium cooled fast reactors core (Na-FBR). Sudden liquid evacuation between assemblies could lead to overall core movements (flowering and compaction) causing variations of core reactivity. The comprehension of the structure behavior during the evacuation could improve the knowledge about some SCRAMs for negative reactivity occurred in PHÉNIX reactor and could contribute on the study of the dynamic behavior of a FBR core. An experimental facility (PISE-2c) is designed composed by a Poly-methyl methacrylate hexagonal rods (2D-plan similitude with PHÉNIX assembly) with a very thin gap between assemblies. Another experimental device (PISE-1a) is designed and composed by a single hexagonal rod for testing the dynamic characteristics. Different experiments are envisaged: free vibrations and oscillations during water injection. A phenomenological analysis is reported showing the flow behavior in the gap and the structure response. Also computational simulations are presented in this paper. An efficient numerical method is used to solve Navier-Stokes equations coupled with structure dynamic equation. The numerical method is verified by the comparison of analytic models and experiments.
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Opinel, Pierre-Adrien, and Narakorn Srinil. "Phenomenological Modelling of Cylinder VIV With Contributions From Oscillatory Flows." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77689.
Повний текст джерелаАнотація:
This paper presents a numerical phenomenological model for a two-degree-of-freedom VIV of a flexibly mounted circular rigid cylinder subject to sinusoidal oscillatory flows. This prediction model is based on the use of double Duffing-van der Pol (structure-wake) oscillators which capture the structural geometrical coupling and fluid-solid interaction effects through system cubic-quadratic nonlinearities. Empirical coefficients are calibrated based on computational fluid dynamics results in the literature for the Keulegan-Carpenter numbers (KC) of 10, 20 and 40, satisfying a reasonable correspondence in amplitude and frequency responses. For KC = 10, the cross-flow vibrations present a single-frequency response. For KC = 20 and 40, cross-flow vibrations have multi-frequency responses. The primary frequency of the response in the cross-flow direction decreases with increasing reduced velocity, except for small values of the reduced velocities. In all KC cases, the in-line vibrations exhibit mostly a single frequency. Overall, parametric studies capture the dependence of response characteristics on the KC, reduced velocity, mass ratio, frequency ratios and empirical coefficients.
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Byrtus, Miroslav, Štěpán Dyk, and Michal Hajžman. "Non-Synchronous Vibration and Lock-in Regimes in Coupled Structures Using Reduced Models." In ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-66815.
Повний текст джерелаАнотація:
Abstract The contribution is aimed at phenomenological modelling and analysis of fundamental properties of non-synchronous vibrations in chosen coupled structures. A van der Pol reduced-order model is employed to simulate the aero-elastic interaction between flexible bodies and fluid. Non-synchronous vibration and frequency lock-in, along with hysteresis, are captured in the main resonance area. Moreover, the model reveals subharmonic resonances accompanied by the existence of unstable solutions and frequency lock-in. The study is further extended to investigate the dynamical behaviour of a coupled cyclic structure, where different modes of vibration due to the aero-elastic interaction are analysed.
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Hovey, Chad B., Matthew L. Kaplan, and Jean H. Heegaard. "A Viscoelastic Model for Finite Deformation of Soft Tissue." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0121.
Повний текст джерелаАнотація:
Abstract The ubiquitous presence of soft tissue in the human body has provided significant motivation for researchers to model its behavior. Specifically, soft tissue models for cartilage have been extensively developed. The biphasic (Mow et al., 1984) model has provided a foundation for the understanding of cartilage behavior, grounded in a solid-fluid interaction point-of-view. Phenomenological approaches have also been made, borrowing developments from viscoelasticity and applying those models to biomechanics. Woo et al. (1980) discussed the viscoelastic properties of cartilage in the context of a quasi-linear theory.
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Lin, Zhiliang, and Longbin Tao. "HAM Solutions for Vortex-Induced Vibration of a Circular Cylinder." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-24111.
Повний текст джерелаАнотація:
The vortex-induced vibration (VIV) phenomenon is result of fluid-structure interaction which occurs in many engineering fields. The study of VIV of a circular cylinder is of practical importance (such as in marine cables and flexible risers in petroleum production). In this paper, one classical phenomenological VIV model — the motion of the cylinder is modeled by a simple linear equation, and the fluctuating nature of the vortex wake oscillation is modeled by a van der Pol oscillator, is analyzed. Firstly, the homotopy analysis method (HAM), a powerful technique for highly nonlinear problems, is developed to solve the coupled fluid-structure dynamical system with the convergence of the homotopy series solutions being demonstrated. Based on the HAM solutions, some properties of the fully nonlinear classical coupled VIV model are presented. All the results proved that the proposed HAM scheme has potential to be an effective analytic technique to study the VIV problems.
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Tagliaferri, Francesca, and Narakorn Srinil. "Quantifying Uncertainties in Phenomenological Model of Two-Dimensional VIV Using Multivariate Monte Carlo Simulations." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61058.
Повний текст джерелаАнотація:
Phenomenological modelling based on the use of coupled wake-cylinder oscillators has been implemented for several decades for vortex-induced vibration (VIV) response predictions of rigid circular cylinders and long flexible risers. Although such models can capture several VIV nonlinear phenomena, they still rely on empirical coefficients and parameters with some levels of uncertainties associated with fluid-structure interactions. Most of these are due to the variation in experimental test conditions giving rise to different benchmarking test data in the literature. A very few studies have quantified such model uncertainties. To gain an insight into the relative contributions of these coefficients, this paper presents a sensitivity study based on a multivariate Sobol-Monte Carlo approach for a two-dimensional nonlinear coupled wake-cylinder oscillator model simulating combined cross-flow/in-line VIV. A preliminary investigation is carried out to identify the relative contribution to the model uncertainty of the geometrical, empirical wake and wake-cylinder coupling coefficients. The effect of Reynolds number (Re) in the subcritical flow regime is also taken into account through a lift, drag, Strouhal and wake coefficient depending on calibration with experimental data. A key challenge is the identification of suitable probability distribution function to model the scattering experimental datasets. A combination of Gaussian and uniform distributions are calibrated. Parametric studies based on the combined Sobol-Monte Carlo simulations reveal the uncertainties due to the coupling of empirical coefficients and system parameters governing the two-dimensional lock-in and combined cross-flow/in-line VIV responses. The relative importance of the selected wake coefficients and geometric parameters appears to be strongly dependent on the system mass ratio as well as Re influencing the hydrodynamic properties including the lift and drag coefficients, the Strouhal number and stall parameter. For the cylinder with a lower mass ratio, greater uncertainties are found within the considered sub-critical Re range for both cross-flow/in-line VIV. This remark should also be recognized in the phenomenological VIV modelling of long flexible risers in offshore applications.
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Hendrikse, Hayo, Frank W. Renting, and Andrei V. Metrikine. "Analysis of the Fatigue Life of Offshore Wind Turbine Generators Under Combined Ice- and Aerodynamic Loading." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23884.
Повний текст джерелаАнотація:
A modelled wind turbine generator subjected to combined ice- and aerodynamic loading is analyzed with the focus on its fatigue lifetime. A comparison is made between the prediction of a combined analysis, taking both ice- and wind loads into account simultaneously, and a superposition analysis, computing the response of the structure as a result of ice and wind loading separately. The accumulated fatigue damage is computed considering different descriptions of the ice load. Prescribed ice load curves from current design standards, as well as phenomenological models for the prediction of dynamic ice-structure interaction are employed. Results show that the superposition method underpredicts the accumulated fatigue damage in the range of frequency lock-in, but only when phenomenological models, which are more advanced than those recommended by the design standards, are used to model the ice load. Furthermore the predicted fatigue damage computed using the design standards for the description of the ice load is found to be much larger than that resulting from the application of the phenomenological models. It is concluded that the combined analysis is desired when phenomenological models are applied. Furthermore, improvement of the predictive capabilities of such models might ultimately lead to a reduction of the predicted fatigue damage accumulation of the combined ice- and aerodynamic load case, as compared to the current prescribed methods in standards.
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Aghav, Y. V., P. A. Lakshminarayanan, M. K. G. Babu, N. S. Nayak, and A. D. Dani. "Phenomenology of Smoke From Direct Injection Diesel Engine." In ASME 2005 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/icef2005-1350.
Повний текст джерелаАнотація:
A phenomenological model for smoke prediction from a direct injection (DI) diesel engine is newly evolved from an eddy dissipation model of Dent [1]. The turbulence structure of fuel spray is developed by incorporating the wall impingement to explain smoke formed in free and wall portions. The spray wall interaction is unavoidable in case of modern DI diesel engines of bore less than 125 mm. The new model is one dimensional and based on the recent phenomenological description of spray combustion in direct injection diesel engine. Integration of net soot rate and no need to use empirical tuning constants are the important features, which distinguish the model from existing models. Smoke values are successfully predicted using this model for an engine with heavy-duty applications under widely varying operating conditions.
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El Bouzidi, Salim, Marwan Hassan, and Samir Ziada. "Characterization of Flow-Sound-Structure Coupling in Spring-Loaded Valves." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65767.
Повний текст джерелаАнотація:
The purpose of this study is to investigate the vibration mechanism of a spring-loaded valve placed in a “push-to-open” configuration in a piping system. A non-linear theoretical model of the valve vibration is developed to describe the interaction mechanisms between the unsteady flow through the valve, the acoustic field in the piping system, and the oscillation of the valve plate. The aim of this phenomenological model is to better understand the main system parameters causing the valve vibration. The model relies on a one-dimensional unsteady Bernoulli representation of the flow and a single degree of freedom model of the valve plate motion with impact conditions at the valve seat and lift limiter. Impact forces are determined through the means of a pseudo-force method. The model is cast in state-space form and solved using a fourth-order Runge-Kutta stencil. The predicted limit cycle amplitudes follow the same trends as experimental findings over the opening range of the valve. Modal characteristics are also consistent with experimental data.
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Heinonen, Jaakko. "Modelling Techniques and Case Study of Explicit 3D FE-Simulation of Ridge Loads Against an Offshore Structure." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79113.
Повний текст джерелаАнотація:
A ridge interaction with an offshore structure, Norstro¨msgrund lighthouse in the Gulf of Bothnia, was simulated by the finite element method (FEM) utilizing the explicit solution algorithm. The explicit method in a dynamic analysis enabled an efficient way to simulate the failure of a ridge. A shear-cap material model describing the ice rubble mechanical behaviour was developed for the 3-dimensional analysis and implemented into ABAQUS FEM-software as a user material subroutine. The FE-model described the ridge: the sail and keel consisting of ice rubble and the consolidated layer close to the waterline. A selected ridge-interaction event was simulated with a simplified geometry, based on measurements carried out in the STRICE project. The ridge field was idealized to have a constant thickness. The shape of a 3-dimensional structure was modelled using rigid elements. The phenomenological model can be utilized to gain an understanding of how the ridge fails during the interaction with an offshore structure, what the ridge loads are, and how they are distributed against the structure. A parametric study was carried out to study how the mechanical properties, i.e. the cohesion and friction angle of the rubble and the strength of the consolidated layer influence the forces and failure mechanisms.
Звіти організацій з теми "Phenomenological fluid-structure interaction model"
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Torres, Marissa, Michael-Angelo Lam, and Matt Malej. Practical guidance for numerical modeling in FUNWAVE-TVD. Engineer Research and Development Center (U.S.), October 2022. http://dx.doi.org/10.21079/11681/45641.
Повний текст джерелаАнотація:
This technical note describes the physical and numerical considerations for developing an idealized numerical wave-structure interaction modeling study using the fully nonlinear, phase-resolving Boussinesq-type wave model, FUNWAVE-TVD (Shi et al. 2012). The focus of the study is on the range of validity of input wave characteristics and the appropriate numerical domain properties when inserting partially submerged, impermeable (i.e., fully reflective) coastal structures in the domain. These structures include typical designs for breakwaters, groins, jetties, dikes, and levees. In addition to presenting general numerical modeling best practices for FUNWAVE-TVD, the influence of nonlinear wave-wave interactions on regular wave propagation in the numerical domain is discussed. The scope of coastal structures considered in this document is restricted to a single partially submerged, impermeable breakwater, but the setup and the results can be extended to other similar structures without a loss of generality. The intended audience for these materials is novice to intermediate users of the FUNWAVE-TVD wave model, specifically those seeking to implement coastal structures in a numerical domain or to investigate basic wave-structure interaction responses in a surrogate model prior to considering a full-fledged 3-D Navier-Stokes Computational Fluid Dynamics (CFD) model. From this document, users will gain a fundamental understanding of practical modeling guidelines that will flatten the learning curve of the model and enhance the final product of a wave modeling study. Providing coastal planners and engineers with ease of model access and usability guidance will facilitate rapid screening of design alternatives for efficient and effective decision-making under environmental uncertainty.