Pipe cooling is an important measure for controlling the temperature of mass concrete during the hydration period. In this paper, a new algorithm (partitionediterative algorithm, PIA) is proposed to address the compl...
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Pipe cooling is an important measure for controlling the temperature of mass concrete during the hydration period. In this paper, a new algorithm (partitionediterative algorithm, PIA) is proposed to address the complicated process of dissecting cooling pipes in mass concrete and the difficulty of balancing the accuracy and efficiency of the simulation. The algorithm is based on the idea of finite element partitioning, where the water pipe element and the concrete element are considered as two computational parts. The coupling is used to consider the heat transfer between the water pipe and the concrete, avoiding the need to solve for the concrete temperature gradient in the vicinity of the pipe, which improves the efficiency of the algorithm. The comparison of the PIA and the discrete iterative algorithm (DIA) results demonstrates the agreement between the two algorithms in terms of computational accuracy and distribution pattern. In addition, the automatic creation and insertion of the pipe elements results in a significant improvement of the overall performance. Finally, the engineering example demonstrates that the results of the PIA at each observation point agree well with the measured values over the entire calculation time. The accuracy of the calculated peak temperature and the peak temperature age can both meet the engineering requirements.
Fluid-structure interaction (FSI) is an interdependent phenomenon between a fluid and a structure that affects their dynamic behavior. It is important because it often affects the safety and lifetime of structures. Th...
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Fluid-structure interaction (FSI) is an interdependent phenomenon between a fluid and a structure that affects their dynamic behavior. It is important because it often affects the safety and lifetime of structures. Therefore, controlling FSI is important. In the study of the control of FSI, numerical simulations are often used because they are suitable for parametric studies and reduce the need for experiments. A number of numerical studies have examined the control of FSI. However, existing numerical studies have rarely performed both fluid and structural analyses strictly and sufficiently treated interaction conditions on the coupling interface. Therefore, the types of FSI problems that can be analyzed are limited. In order to enable the treatment of a greater variety of FSI problems, it was necessary to develop a new method. The partitioned iterative method has succeeded in analyzing complicated FSI problems, and, in the present study, we propose FSI analysis considering active control by integrating FSI analysis by a partitioned iterative method and an active control algorithm. We explain the proposed method, and we validate the method by solving two-dimensional vortex-induced vibration (VIV) of an elastically mounted cylinder with active control of a velocity feedback. Furthermore, we present an application example by solving the suppression of two-dimensional VIV of a flexible structure in the wake of a bluff body.
Piezoelectric structure fluid interaction is a complex multiphysics coupled phenomena appears wherein piezoelectric devices are in contact or surrounded by the fluid media. The piezoelectric energy harvesting using oc...
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ISBN:
(纸本)9788494919459
Piezoelectric structure fluid interaction is a complex multiphysics coupled phenomena appears wherein piezoelectric devices are in contact or surrounded by the fluid media. The piezoelectric energy harvesting using ocean waves, wind flow, and mechanical vibrations are some of the popular energy savaging methods wherein thin piezoelectric bimorphs surrounded by the fluid is used for power harvesting. With recent advances on micro air vehicles actuated by piezoelectric bimorph actuators in the fluid (surrounding media) as attracted the of piezoelectric structure fluid interaction. Generally, in these applications, the piezoelectric bimorph is thin, flexible, and surrounded by the fluid. The large deformation of the thin flexible piezoelectric bimorph causes strong interaction with the electric field (piezoelectric effect) and the surrounding fluid, and inversely, these two fields significantly affect the structure. The piezoelectric field structure fluid interaction analysis is very significant. In this work, we propose a hierarchal decomposition method to solve piezoelectric structure fluid interaction of a piezoelectric bimorph in the fluid. The proposed method is applied to a flexible restrictor flap in converging channel, where the rubber flap is replaced by the piezoelectric bimorphs made of PVDF or PZT-5H. The resonance frequency of the piezoelectric bimorph in the fluid agrees well with the theoretical and numerical pure FSI cases. These results show a good agreement with the previous studies.
Recently tightly coupled partitioned iterative methods have drawn a great deal of attention due to easy implementation and encapsulation features, and many nonlinear algorithms have been proposed so far. However, thei...
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Recently tightly coupled partitioned iterative methods have drawn a great deal of attention due to easy implementation and encapsulation features, and many nonlinear algorithms have been proposed so far. However, their practical performances have not been well understood yet. This paper describes the intensive parametric study on convergence and stability performances of four kinds of nonlinear algorithms with line-search techniques for partitioned iterative methods of steady/unsteady fluid-structure interaction (FSI) problems. Here we choose three typical FSI problems as test problems, i.e. (1) Collapsible channel as a steady problem, (2) Cavity with flexible bottom membrane and (3) Channel with flexible wall as unsteady problems. Efficiency and robustness dependency of those nonlinear algorithms on physical parameters such as degree of nonlinearity, added mass effect, time step, and control parameters peculiar to each algorithm are clarified. Through those tests, we demonstrate that the Line extrapolation method and Broyden method with Backtrack line-search technique show good performances in both stability and efficiency. Copyright (C) 2010 John Wiley & Sons, Ltd.
This work presents multiphysics numerical analysis of piezoelectric actuators realized using the finite element method (FEM) and their performances to analyze the structure-electric interaction in three-dimensional (3...
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This work presents multiphysics numerical analysis of piezoelectric actuators realized using the finite element method (FEM) and their performances to analyze the structure-electric interaction in three-dimensional (3D) piezoelectric continua. Here, we choose the piezoelectric bimorph actuator without the metal shim and with the metal shim as low-frequency problems and a surface acoustic wave device as a high-frequency problem. More attention is given to low-frequency problems because in our application micro air vehicle's wings are actuated by piezoelectric bimorph actuators at low frequency. We employed the Newmark's time integration and the central difference time integration to study the dynamic response of piezoelectric actuators. Monolithic coupling, noniterativepartitioned coupling and partitionediterative coupling schemes are presented. In partitionediterative coupling schemes, the block Jacobi and the block Gauss-Seidel methods are employed. Resonance characteristics are very important in micro-electro-mechanical system (MEMS) applications. Therefore, using our proposed coupled algorithms, the resonance characteristics of bimorph actuator is analyzed. Comparison of the accuracy and computational efficiency of the proposed numerical finite element coupled algorithms have been carried out for 3D structure-electric interaction problems of a piezoelectric actuator. The numerical results obtained by the proposed algorithms are in good agreement with the theoretical solutions.
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