This investigation aims at assessing the fluid-structure interaction (FSI) occurring during hydraulic transients in straight pipeline systems fixed to anchor blocks. A two mode 4-equation model is implemented incorpor...
详细信息
This investigation aims at assessing the fluid-structure interaction (FSI) occurring during hydraulic transients in straight pipeline systems fixed to anchor blocks. A two mode 4-equation model is implemented incorporating the main interacting mechanisms: Poisson, friction and junction coupling. The resistance to movement due to inertia and dry friction of the anchor blocks is treated as junction coupling. Unsteady skin friction is taken into account in friction coupling. Experimental waterhammer tests collected from a straight copper pipe-rig are used for model validation in terms of wave shape, timing and damping. Numerical results successfully reproduce laboratory measurements for realistic values of calibration parameters. The novelty of this paper is the presentation of a 1D FSI solver capable of describing the resistance to movement of anchor blocks and its effect on the transient pressure wave propagation in straight pipelines. (C) 2017 Elsevier Ltd. All rights reserved.
This paper describes recent studies devoted to the problem of modeling the solid-fluidinteraction in partially filled liquid containers. This problem is of much importance for numerous applications, including those i...
详细信息
This paper describes recent studies devoted to the problem of modeling the solid-fluidinteraction in partially filled liquid containers. This problem is of much importance for numerous applications, including those in the airspace industry (rockets, satellites), road and naval transportation, and has become in recent years an object of keen interest from researchers. The paper focuses in particular on the sloshing phenomenon and on the numerical approaches used to predict the sloshing wave amplitude, frequency, pressure exerted on the walls and the effect of sloshing on the stability in the container environment. Recent publications devoted to sloshing and fluid-structure interaction are reviewed and the numerical methods used in then are exposed and classified according to the problem formulations employed. They concern primarily finite-elements and finite-differences methods applied to Euler or Lagrangian fluid and solid domains, as well as the smoothed particle method. Issues related to modeling the free-surface of the fluid, fluid-solid interface and to numerical coupling are exposed. Results obtained by various numerical methods are discussed in comparison with experimental results, where possible. Applications of sloshing models in naval, aerospace and other industries are described and discussed. (C) 2010 Elsevier Ltd. All rights reserved.
This work presents a strongly-coupled fluid-structure interaction (FSI) formulation for compressible flows that is developed based on an augmented Lagrangian approach. The method is suitable for handling problems that...
详细信息
This work presents a strongly-coupled fluid-structure interaction (FSI) formulation for compressible flows that is developed based on an augmented Lagrangian approach. The method is suitable for handling problems that involve nonmatching fluid-structure interface discretizations. In this work, the fluid is modeled using a stabilized finite element method for the Navier-Stokes equations of compressible flows and is coupled to the structure, which is formulated using isogeometric Kirchhoff-Love shells. The strongly-coupled system is solved using a block-iterative approach. The proposed method is validated using two compressible flow benchmark problems to assess the accuracy of the developed formulation.
In the present work a new approach to solve fluid-structure interaction problems is described. Both, the equations of motion for fluids and for solids have been approximated using a material (Lagrangian) formulation. ...
详细信息
In the present work a new approach to solve fluid-structure interaction problems is described. Both, the equations of motion for fluids and for solids have been approximated using a material (Lagrangian) formulation. To approximate the partial differential equations representing the fluid motion, the shape functions introduced by the meshless finite element method (MFEM) have been used. Thus, the continuum is discretized into particles that move under body forces (gravity) and surface forces (due to the interaction with neighboring particles). All the physical properties such as density, viscosity, conductivity, etc., as well as the variables that define the temporal state such as velocity and position and also other variables like temperature are assigned to the particles and are transported with the particle motion. The so called particle finite element method (PFEM) provides a very advantageous and efficient way for solving contact and free-surface problems, highly simplifying the treatment of fluid-structure interactions. (c) 2005 Elsevier B.V. All rights reserved.
Crashworthiness of subfloor-integrated tank is fundamental for the survivability of an impact with the ground in emergency. In this paper, numerical models for the analysis of the water sloshing in a tank during the i...
详细信息
Crashworthiness of subfloor-integrated tank is fundamental for the survivability of an impact with the ground in emergency. In this paper, numerical models for the analysis of the water sloshing in a tank during the impact with the ground have been developed and validated using experimental data. Specific drop tests were carried out using simulacra of a tank integrated in the subfloor of a small dimension helicopter and reproduced in detail using LSTC LS-Dyna. In particular, four different models were developed for the water inside the tank namely: Finite Element (FE), Eulerian, Arbitrary Lagrangian Eulerian, and Smoothed Particles Hydrodynamics (SPH) model. Advantages and disadvantages of these models were evaluated and the results show that the FE model of the water is the most feasible for the analysis of the tank structure damages whereas the SPH model of the water, despite the large required CPU time, is the most feasible for the analysis of the sloshing of the water. (C) 2004 Elsevier Ltd. All rights reserved.
Pressure-compensating (PC) emitters can maintain a constant discharge within a wide range of working pressures, thus they have extensive application prospect in mountain regions where the hydraulic pressure in irrigat...
详细信息
Pressure-compensating (PC) emitters can maintain a constant discharge within a wide range of working pressures, thus they have extensive application prospect in mountain regions where the hydraulic pressure in irrigation systems often changes greatly. Although the rapid design method for non-PC emitters based on CFD is quite mature at present, common CFD method is not suitable for the design of PC emitters because a two-way coupling interaction exists between the fluid flow and elastic diaphragm. In order to improve the design accuracy and efficiency of PC emitters, the fluid-structure interaction (FSI) analysis was studied in this paper. In the FSI analysis procedure, adaptive mesh repair was adopted to refine the distorted fluid mesh. Incremental method and displacement-pressure finite element formula were used for the nonlinear analysis of the incompressible material. In this article, SST K-omega turbulence model was used for the fluid analysis, while contact analysis method and Neo-Hookean Mooney-Rivlin rubber material model were adopted for the structure analysis. The results showed that the discharge was adjusted by a very small deformation of the diaphragm to reach a steady state. At last, compared with the test results carried out using the test samples made by rapid prototyping, the analyzed values were a little larger while the maximum relative deviation was within 2.5%. This verified that PC emitter's discharge could be predicted by FSI analysis accurately. In conclusion, FSI analysis is an efficient way to improve the design accuracy and reduce the test times for PC emitters.
Various numerical procedures, which each have respective merits and drawbacks, are available for the investigation of fluid-structure interaction problems. This paper concentrates on the coupling of the finite element...
详细信息
Various numerical procedures, which each have respective merits and drawbacks, are available for the investigation of fluid-structure interaction problems. This paper concentrates on the coupling of the finite element method, used to model the structure, and the boundary element method representing the fluid. Both methods are formulated in the time domain and a special algorithm is developed to realize the coupling. In particular, nonlinear effects, such as material nonlinearities, large displacements or unilateral boundary conditions, may be taken into account in the structural model, while an infinite expansion of the fluid region is included in the boundary element formulation. Numerical examples exhibit the applicability of the new approach. It is observed that nonlinearities may have a considerable effect on the behavior of the fluid-structure system. (C) 2002 Elsevier Science Ltd. All rights reserved.
In the present work the problem of fluid-structure interaction (FSI) with independently space discretized fluid and structure fields is addressed in the context of finite elements. To be able to deal with non-conformi...
详细信息
In the present work the problem of fluid-structure interaction (FSI) with independently space discretized fluid and structure fields is addressed in the context of finite elements. To be able to deal with non-conforming meshes at the fluid-structure interface, we propose the integration of a dual mortar method into the general FSI framework. This method has lately been used successfully to impose interface constraints in other contexts such as finite deformation contact. The main focus is set on monolithic coupling algorithms for FSI here. In these cases the dual mortar approach allows for the elimination of the additional Lagrange multiplier degrees of freedom from the global system by condensation. The resulting system matrices have the same block structure as their counterparts for the conforming case and permit the same numerical treatment. Partitioned Dirichlet-Neumann coupling is also considered briefly and it is shown that the dual mortar approach permits a numerically efficient mapping between fluid and structure quantities at the interface. Numerical examples demonstrate the efficiency and robustness of the proposed method. We present results for a variety of different element formulations for the fluid and the structure field, indicating that the proposed method is not limited to any specific formulation. Furthermore, the applicability of state-of-the-art iterative solvers is considered and the convergence behavior is shown to be comparable to standard simulations with conforming discretizations at the interface. (C) 2011 Elsevier By. All rights reserved.
The effects of elastic anisotropy in piping materials on fluid-structure interaction are studied for water-filled carbon-fiber reinforced thin plastic pipes. When an impact is introduced to water in a pipe, there are ...
详细信息
The effects of elastic anisotropy in piping materials on fluid-structure interaction are studied for water-filled carbon-fiber reinforced thin plastic pipes. When an impact is introduced to water in a pipe, there are two waves traveling at different speeds. A primary wave corresponding to a breathing mode of pipe travels slowly and a precursor wave corresponding to a longitudinal mode of pipe travels fast. An anisotropic stress-strain relationship of piping materials has been taken into account to describe the propagation of primary and precursor waves in the carbon-fiber reinforced thin plastic pipes. The wave speeds and strains in the axial and hoop directions are calculated as a function of carbon-fiber winding angles and compared with the experimental data. As the winding angle increases, the primary wave speed increases due to the increased stiffness in the hoop direction, while the precursor wave speed decreases. The magnitudes of precursor waves are much smaller than those of primary waves so that the effect of precursor waves on the deformation of pipe is not significant. The primary wave generates the hoop strain accompanying the opposite-signed axial strain through the coupling compliance of pipe. The magnitude of hoop strain induced by the primary waves decreases with increasing the winding angle due to the increased hoop stiffness of pipe. The magnitude of axial strain is small at low and high winding angles where the coupling compliance is small. (C) 2012 Elsevier Ltd. All rights reserved.
In bioengineering applications problems of flow interacting with elastic solid are very common. We formulate the problem of interaction for an incompressible fluid and an incompressible elastic material in a fully cou...
详细信息
In bioengineering applications problems of flow interacting with elastic solid are very common. We formulate the problem of interaction for an incompressible fluid and an incompressible elastic material in a fully coupled arbitrary Lagrangian-Eulerian (ALE) formulation. The mathematical description and the numerical schemes are designed in such a way that more complicated constitutive relations (and more realistic for bioengineering applications) can be incorporated easily. The whole domain of interest is treated as one continuum and the same discretization in space (FEM) and time (Crank-Nicholson) is used for both, solid and fluid, parts. The resulting nonlinear algebraic system is solved by an approximate Newton method. The combination of second order discretization and fully coupled solution method gives a method with high accuracy and robustness. To demonstrate the flexibility of this numerical approach we apply the same method to a mixture-based model of an elastic material with perfusion which also falls into the category of fluidstructureinteractions. A few simple example calculations with simple material models and large deformations of the solid part are presented. (c) 2006 Elsevier Ltd. All rights reserved.
暂无评论