Simulation of the Fluid-Structure Interaction Involving Two-Phase Flow and Hexagonal Structures in a Nuclear Reactor Core

This paper will present a high fidelity solution algorithm for a model of a nuclear reactor core barrel. This model consists of a system of nine nonlinearly coupled partial differential equations. The coolant is modeled with the 1-D six-equation two-phase flow model of RELAP5. Nonlinear heat conduction is modeled with a single 2-D equation. The fission power comes from two 2-D equations for neutron diffusion and precursor concentration. The solution algorithm presented will be the physics-based preconditioned Jacobian-free Newton-Krylov (JFNK) method. In this approach all nine equations are discretized and then solved in a single nonlinear system. Newtons method is used to iterate the nonlinear system to convergence. The Krylov linear solution method is used to solve the matrices in the linear steps of the Newton iterations. The physics-based preconditioner provides an approximation to the solution of the linear system that accelerates the Krylov iterations. Results will be presented for two algorithms. The first algorithm will be the traditional approach used by RELAP5. Here the two-phase flow equations are solved separately from the nonlinear conduction and neutron diffusion. Because of this splitting of the physics, and the linearizations employed this method is first order accurate in time. A second algorithm will be the JFNK method solved second order in time accurate. Results will be presented which compare these two algorithms in terms of accuracy and efficiency.

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An Overview of Numerical Method for Fluid-Structure Interaction

Volume 4: Fluid-Structure Interaction ◽

10.1115/pvp2014-28916 ◽

2014 ◽

Author(s):

J.-H. Jeong ◽

M. Kim ◽

P. Hughes

Keyword(s):

Numerical Simulation ◽

Numerical Methods ◽

Nuclear Power ◽

Power Plants ◽

Fluid Structure Interaction ◽

Phase Flow ◽

Two Phase ◽

Fluid Structure ◽

Structure Interaction ◽

Deformable Structure

Fluid-structure interaction (FSI) is the interaction of some movable or deformable structure with an internal or surrounding fluid flow. Therefore, fluid-structure interaction problems are too complex to solve analytically and so they have to be analysed by means of experiments or numerical simulation. This paper provides an overview of numerical methods for fluid-structure interaction evaluation in an draft IAEA technical guideline: large eddy simulation (LES), direct numerical simulation (DNS), Lattice-Boltzmann method (LBM), finite element method (FEM) and computational fluid dynamics (CFD) method. In addition to providing general applications of numerical methods for fluid-structure interaction evaluation, the paper also describes some cases applied for problems associated with single-phase flow and two-phase flow in nuclear power plants.

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A hybrid level set–front tracking finite element approach for fluid–structure interaction and two-phase flow applications

Journal of Computational Physics ◽

10.1016/j.jcp.2013.08.018 ◽

2013 ◽

Vol 255 ◽

pp. 228-244 ◽

Cited By ~ 17

Author(s):

Steffen Basting ◽

Martin Weismann

Keyword(s):

Finite Element ◽

Level Set ◽

Two Phase Flow ◽

Fluid Structure Interaction ◽

Front Tracking ◽

Phase Flow ◽

Two Phase ◽

Finite Element Approach ◽

Structure Interaction ◽

Element Approach

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Coupling Analysis of Fluid-Structure Interaction and Flow Erosion of Gas-Solid Flow in Elbow Pipe

Advances in Mechanical Engineering ◽

10.1155/2014/815945 ◽

2014 ◽

Vol 6 ◽

pp. 815945 ◽

Cited By ~ 3

Author(s):

Hongjun Zhu ◽

Hongnan Zhao ◽

Qian Pan ◽

Xue Li

Keyword(s):

Erosion Rate ◽

Structural Changes ◽

Fluid Structure Interaction ◽

Fluid Phase ◽

Diameter Ratio ◽

Pipe Diameter ◽

Discrete Phase Model ◽

Two Phase ◽

Fluid Structure ◽

Structure Interaction

A numerical simulation has been conducted to investigate flow erosion and pipe deformation of elbow in gas-solid two-phase flow. The motion of the continuous fluid phase is captured based on calculating three-dimensional Reynolds-averaged-Navier-Stokes (RANS) equations, while the kinematics and trajectory of the discrete particles are evaluated by discrete phase model (DPM), and a fluid-structure interaction (FSI) computational model is adopted to calculate the pipe deformation. The effects of inlet velocity, pipe diameter, and the ratio of curvature and diameter on flow feature, erosion rate, and deformation of elbow are analyzed based on a series of numerical simulations. The numerical results show that flow field, erosion rate, and deformation of elbow are all sensitive to the structural changes and inlet condition changes. Higher inlet rate, smaller curvature diameter ratio, or smaller pipe diameter leads to greater deformation, while slower inlet rate, larger curvature diameter ratio, and larger pipe diameter can weaken flow erosion.

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Fluid structure behaviour in gas-oil two-phase flow in a moderately large diameter vertical pipe

Chemical Engineering Science ◽

10.1016/j.ces.2018.04.075 ◽

2018 ◽

Vol 187 ◽

pp. 377-390 ◽

Cited By ~ 6

Author(s):

Rajab Omar ◽

Buddhika Hewakandamby ◽

Abdelwahid Azzi ◽

Barry Azzopardi

Keyword(s):

Two Phase Flow ◽

Large Diameter ◽

Phase Flow ◽

Gas Oil ◽

Vertical Pipe ◽

Two Phase ◽

Fluid Structure

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A Homogenization Method for the Modal Analysis of a Nuclear Reactor With Fluid-Structure Interaction

Volume 4: Fluid Structure Interaction, Parts A and B ◽

10.1115/pvp2006-icpvt-11-93013 ◽

2006 ◽

Cited By ~ 2

Author(s):

Jean-Franc¸ois Sigrist ◽

Daniel Broc

Keyword(s):

Modal Analysis ◽

Nuclear Reactor ◽

Mass Operator ◽

Fluid Structure Interaction ◽

Homogenization Method ◽

Theoretical Point ◽

Element Discretization ◽

Fluid Structure ◽

Structure Interaction ◽

Internal Structures

The present paper exposes a homogenization method developed in order to perform the modal analysis of a nuclear reactor with fluid-structure interaction effects. The homogenization approach is used in order to take into account the presence of internal structures within the pressure vessel. A homogenization method is proposed in order to perform a numerical calculation of the frequencies and modal masses for the eigenmodes of the coupled fluid-structure problem. The technique allows the use of a simplified fluid-structure model that takes into account the presence of internal structures: the theory bases are first recalled, leading to a new formulation of the fluid-structure coupled problem. The finite element discretization of the coupled formulation leads to the modification of the classical fluid-structure interaction operators. The consistency of the formulation is established from a theoretical point of view by evaluating the total mass of the coupled system with the fluid and structure mass operator, and the modified added mass operator. The method is tested and validated on a 2D case (two concentric cylinders with periodical rigid inclusions within the annular space) and applied on the industrial case. A complete modal analysis (calculation of frequencies and modal masses) is performed on a simplified geometry of a nuclear reactor with and without internal structures. Numerical results are then compared and discussed, and the influence of the internal structures on the fluid-structure coupled phenomenon is highlighted.

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