On the Dynamic Response of Flexible Risers Caused by Internal Slug Flow

2012 ◽  
Author(s):  
Arturo Ortega ◽  
Ausberto Rivera ◽  
Ole Jørgen Nydal ◽  
Carl M. Larsen
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Slug Flow ◽  
Time Integration ◽  
Flow Dynamics ◽  
Two Phase ◽  
Structural Dynamic ◽  
Linear Finite Element ◽  
Flow Through ◽  
Flexible Risers

Slug flow through flexible risers is a frequent phenomenon which occurs during production of a mixture of oil and gas. The dynamic nature of the slug pattern induces time varying forces, which leads to structural vibrations of the riser. These vibrations can produce large deflections and stresses, which can leave it to fail by fatigue, excessive bending or local buckling. In this work the influence from slug flow on the structural dynamic response of a lazy wave flexible riser is analyzed using a computational tool consisting of one program for calculation of slug flow dynamics, and another program for structural dynamic response. Both programs apply a time integration method, and since slug flow will lead to dynamic motion response of the riser, and riser motion dynamics will influence slug flow dynamics, the two codes need to exchange information during the integration process. Information exchange is established by making a federation based on High Level Architecture (HLA). The federation is composed of SLUGIT and RISANANL. SLUGGIT is a two-phase flow code written in C++ which simulates dynamic slug flow through pipes and riser using a Lagrangian tracking model. RISANANL is a FORTRAN program for static and dynamic structural analysis of slender marine structures based on a finite element formulation. Using the HLA standard these two programs can carry out synchronized time integration and exchange information for each time step. In this work the structural analysis code accomplishes the dynamic response using a linear finite element (FE) formulation. Hence, forces from centripetal acceleration of the internal flow, relative velocity between the riser and surrounding water, and varying gravity of the pipe and content will be accounted for in the dynamic analysis. Displacements, stresses, internal pressure, and outlet flow rates of liquid and gas will be accounted for. The results encourage us to carry out a fully non-linear finite element analysis, in order to have a better understanding of the dynamic behaviour of flexible risers undergoing an unsteady internal two-phase flow.

scholarly journals Dynamics of a two-phase flow through a minichannel: Transition from churn to slug flow

2016 ◽  
Vol 131 (4) ◽  
Author(s):  
Grzegorz Górski ◽  
Grzegorz Litak ◽  
Romuald Mosdorf ◽  
Andrzej Rysak
Keyword(s):  
Slug Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through

Visual and Versatile Hybrid Seismic Testing System Incorporated With Non-Linear Finite Element Analysis

2005 ◽  
Author(s):  
Michiya Sakai ◽  
Ohtomo Keizo ◽  
Yutaka Hagiwara ◽  
Yoshihiro Dozono ◽  
Mayumi Fukuyama ◽  
...  
Keyword(s):  
Finite Element ◽  
Time Integration ◽  
Dynamic Test ◽  
Testing System ◽  
Element Analysis ◽  
Visualization System ◽  
Linear Finite Element ◽  
Non Linear ◽  
Incremental Formulation ◽  
Simulation Testing

Hybrid simulation/testing systems have been developed incorporating a non-linear finite element method with a pseudo-dynamic test. In order to ensure stability and efficiency for time integration, the incremental formulation of the α-OS method has been implemented on this system. Visualization system has also been integrated to recognize both numerical simulation for whole systems and laboratory testing for local parts. Numerical hybrid examinations of the soil structure interaction problem have been conducted on this system. By these results, validity and effectiveness of this system has been demonstrated.

scholarly journals An Analytical-Numerical Model for Two-Phase Slug Flow through a Sudden Area Change in Microchannels

2016 ◽  
Vol 9 (6) ◽  
pp. 1839-1850
Author(s):  
A. Mehdizadeh Momen ◽  
S.A. Sherif ◽  
William Lear ◽  
◽  
◽  
...  
Keyword(s):  
Numerical Model ◽  
Slug Flow ◽  
Two Phase ◽  
Area Change ◽  
Flow Through

Overestimation Analysis of Interval Finite Element for Structural Dynamic Response

2019 ◽  
Vol 11 (04) ◽  
pp. 1950035
Author(s):  
Tuanjie Li ◽  
Hangjia Dong ◽  
Xi Zhao ◽  
Yaqiong Tang
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Structural Parameters ◽  
Upper And Lower Bounds ◽  
Response Analysis ◽  
Uncertain Parameters ◽  
Engineering Structures ◽  
Structural Dynamic ◽  
Dynamic Response Analysis ◽  
Interval Parameters

Dynamic response analysis plays an important role for the structural design. For engineering structures, there exist model inaccuracies and structural parameters uncertainties. Consequently, it is necessary to express these uncertain parameters as interval variables and introduce the interval finite element method (IFEM), in which the elements in stiffness matrix, mass matrix and damping matrix are all the function of interval parameters. The dependence of interval parameters leads to overestimation of dynamic response analysis. In order to reduce the overestimation of IFEM, the element-based subinterval perturbation for static analysis is applied to dynamic response analysis. According to the interval range, the interval parameters are divided into different subintervals. With permutation and combination of each subinterval, the upper and lower bounds of displacement response are obtained. Because of the large number of degrees of freedom and uncertain parameters, the Laplace transform is used to evaluate the dynamic response for avoiding to frequently solve the interval finite element linear equations. The numerical examples illustrate the validity and feasibility of the proposed method.

A Newly Developed Algorithm for Treating the Coupled Dynamic Response of Robotic Fixtureless Assembly

1996 ◽  
Author(s):  
Genady Shagal ◽  
Shaker A. Meguid
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Equations Of Motion ◽  
Time Integration ◽  
Integration Scheme ◽  
The Finite Element Method ◽  
Coupled Equations ◽  
Time Integration Scheme ◽  
Implicit Approach ◽  
Cooperating Robots

Abstract The coupled dynamic response of two cooperating robots handling two flexible payloads for the purpose of fixtureless assembly and manufacturing is treated using a new algorithm. In this algorithm, the equations describing the dynamics of the system are obtained using Lagrange’s method for the rigid robot links and the finite element method for the flexible payloads. A new time integration scheme is developed to treat the coupled equations of motion of the rigid links for a given displacement of the flexible payloads. The finite element equations of the flexible payloads are then treated using an implicit approach. The new algorithm was verified using simplified examples and was later used to examine the dynamic response of two cooperating robot arms manipulating flexible payloads which are typical of the automotive industry.

Slug generation processes in co-current turbulent-gas/laminar-liquid flows in horizontal channels

2018 ◽  
Vol 860 ◽  
pp. 224-257 ◽  
Author(s):  
Sha Miao ◽  
Kelli Hendrickson ◽  
Yuming Liu
Keyword(s):  
Solitary Waves ◽  
Slug Flow ◽  
Flow Dynamics ◽  
Immersed Boundary ◽  
Initial Growth ◽  
Interfacial Waves ◽  
Two Phase ◽  
Interface Evolution ◽  
Resonant Wave ◽  
Liquid Flows

We theoretically and computationally investigate the physical processes of slug-flow development in concurrent two-phase turbulent-gas/laminar-liquid flows in horizontal channels. The objective is to understand the fundamental mechanisms governing the initial growth and subsequent nonlinear evolution of interfacial waves, starting from a smooth stratified flow of two fluids with disparity in density and viscosity and ultimately leading to the formation of intermittent slug flow. We numerically simulate the entire slug development by means of a fully coupled immersed flow (FCIF) solver that couples the two disparate flow dynamics through an immersed boundary (IB) method. From the analysis of spatial/temporal interface evolution, we find that slugs develop through three major cascading processes: (I) stratified-to-wavy transition; (II) development and coalescence of long solitary waves; and (III) rapid channel bridging leading to slugging. In Process I, relatively short interfacial waves form on the smooth interface, whose growth is governed by the Orr–Sommerfeld instability. In Process II, interfacial waves evolve into long solitary waves through multiple resonant and near-resonant wave–wave interactions. From instability analysis of periodic solitary waves, we show that these waves are unstable to their subharmonic disturbances and grow in amplitude and primary wavelength through wave coalescence. The interfacial forcing from the turbulent gas–laminar liquid interactions significantly precipitates the growth of instability of solitary waves and enhances coalescence of solitary waves. In Process III, we show by an asymptotic analysis that interfacial waves achieve multiple-exponential growth right before bridging the channel, consistent with observations in existing experiments. The present study provides important insights for effective modelling of slug-flow dynamics and the prediction of slug frequency and length, important for design and operation of (heavy-oil/gas) pipelines and production facilities.

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