Eulerian Formulation of Fluid-structure Interaction in Reactor Containment System PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
This paper is concerned with an Eulerian formulation for a fluid-structure interface developed for the nonlinear fluid-structure interaction analysis encountered in the primary containment and piping components of nuclear reactors. The Eulerian finite difference methodology is chosen because of its decisive abilities in: (1) investigating material motion with large distortions, (2) treating fluid flow around internal structures having a geometrical discontinuity, (3) handling wave transients in the vicinity of perforated structures. The ultimate objective is to perform the analysis of the reactor integrity when subject to the transient load. Two types of irregular cells are considered and their formulation corresponding to the ICE technique are described. The first one is for interfaces between a coolant and a deformable structure, where the fluid slides tangentially along the moving boundary. A relaxation equation is derived here, allowing the adjustment of the pressure on the moving boundary of the fluid by an amount proportional to the actual mass flux across the boundary. The second irregular cell is for fluid adjacent to the perforated structure where fluid flow through coolant passage takes place. A modified Poisson equation is obtained to appropriately account for the volume perforation and the flow-area availability of the perforated structure. These two equations, in conjunction with the governing Poisson equation of the ICE technique, are solved iteratively. Convergence is attained when boundary conditions at all interfaces are satisified. The development scheme enables the implicit Eulerian hydrodynamic techniques to be coupled with any structural dynamic program. Presently, a corotational coordinate finite element program, WHAMS, is employed for calculating the structural response. Three sample problems are presented to illustrate the analysis. The results are discussed.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
This paper is concerned with an Eulerian formulation for a fluid-structure interface developed for the nonlinear fluid-structure interaction analysis encountered in the primary containment and piping components of nuclear reactors. The Eulerian finite difference methodology is chosen because of its decisive abilities in: (1) investigating material motion with large distortions, (2) treating fluid flow around internal structures having a geometrical discontinuity, (3) handling wave transients in the vicinity of perforated structures. The ultimate objective is to perform the analysis of the reactor integrity when subject to the transient load. Two types of irregular cells are considered and their formulation corresponding to the ICE technique are described. The first one is for interfaces between a coolant and a deformable structure, where the fluid slides tangentially along the moving boundary. A relaxation equation is derived here, allowing the adjustment of the pressure on the moving boundary of the fluid by an amount proportional to the actual mass flux across the boundary. The second irregular cell is for fluid adjacent to the perforated structure where fluid flow through coolant passage takes place. A modified Poisson equation is obtained to appropriately account for the volume perforation and the flow-area availability of the perforated structure. These two equations, in conjunction with the governing Poisson equation of the ICE technique, are solved iteratively. Convergence is attained when boundary conditions at all interfaces are satisified. The development scheme enables the implicit Eulerian hydrodynamic techniques to be coupled with any structural dynamic program. Presently, a corotational coordinate finite element program, WHAMS, is employed for calculating the structural response. Three sample problems are presented to illustrate the analysis. The results are discussed.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The Eulerian algorithm described is capable of analyzing two-dimensionally the fluid-structure interaction in a typical LMFBR containment consisting of various structure components. The algorithm has several special features. First, it employs the Eulerian coordinates in the formulation and enables the technique to be applicable to excursions involving large material distortions. Second, it provides rigorous hydrodynamic analyses at the fluid-structure interface and at the geometrical discontinuities, which is very important in the study of wave-transmission and -diffraction problems. Third, the algorithm incorporates a well-developed finite-element structural program that can account for both material and geometrical nonlinearities. The application of this Eulerian algorithm is not limited to fast reactor containment. It can also be applied to the major piping components, such as valve and IHX, where internal baffle plates may play an important role in the wave propagation. Moreover, the treatment of the time-dependent irregular cell can be integrated with the IMF2 Method and structural dynamics program for investigating the coupled fluid-structure problems involving two-phase flows.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
This report describes a reactor-containment code, ALICE, which uses an arbitrary Lagrangian-Eulerian method to describe the coolant motion, together with a Lagrangian method to analyze the response of the containment vessel and other solid media inside a reactor containment. The finite-difference formulation used to approximate the governing equations for the motion of the coolant can be solved in either an explicit or an implicit scheme; the finite-element formulation used to approximate the governing equations for the containment vessel and other solid media can be performed only in the explicit scheme. Thus, the ALICE code can perform two types of coupling calculations for the fluid and structure (implicit-explicit and explicit-explicit). The code is generalized so that it can apply to problems either in a two-dimensional Cartesian or in a two-dimensional cylindrical-coordinate system.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
An Eulerian method for analyzing large-displacement fluid-structure interaction in reactor containments is presented. The emphasis is on the development of a generalized hydrodynamic scheme to treat the irregular cells created by the movement of the structure with respect to the fixed Eulerian coordinates. A relaxation equation is derived from the boundary condition at the fluid-structure interface for the solution of the pressure at the interface. By combining this with the Poisson equation a sufficient set of equations is obtained for the determination of the advanced-time pressures in the fluid region and at the fluid-structure interfaces. Sample problems are given to illustrate the analysis.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
In this paper, recent developments of a quasi-Eulerian finite element formulation for the treatment of the fluid in fluid-structure interaction problems are described. The present formulation is applicable both to plane two-dimensional and axisymmetric three-dimensional problems. In order to reduce the noise associated with the convection terms, an amplification factor technique is used to implement an up-winding type scheme. The application of the method is illustrated in two problems which are of importance in nuclear reactor safety: (1) a two dimensional model of a cross section of a subassembly configuration, where the quasi-Eulerian formulation is used to model the fluid adjacent to the structures and in the channel between the subassemblies; (2) pressure transients in a straight pipe, where the axisymmetric formulation is used to model the fluid in the pipe. These results are compared to experimental results for these problems and compare quite well.
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Author: C. Y. Wang
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Author: Thomas A. Jaeger