Spelling suggestions: "subject:"coupled analysis"" "subject:"eoupled analysis""
1 |
Numerical simulation of the truss spar 'Horn Mountain' using COUPLETheckum Purath, Basil 16 August 2006 (has links)
A truss spar, named as Horn Mountain, was deployed in the Gulf of Mexico in 1,650 m of water, approximately 150 km southeast of New Orleans in June 2002. Horn Mountain is operated by British Petroleum (B.P.). Extensive field measurements were made using an integrated marine monitoring system attached to the truss spar. In this study, dynamic analysis of the truss spar interacting with its mooring and riser system was performed using a time-domain numerical code, known as ÂCOUPLEÂ. The simulated results were then compared with the corresponding field measurements made during Hurricane Isidore. During the numerical study, various hydrodynamic parameters which were crucial to the accuracy of predicting the global motions of the truss spar and tensions in mooring lines and risers were scrutinized, such as the drag and added-mass coefficients of heave plates, hard tank and truss beams. Satisfactory agreement between the simulation and corresponding measurements was reached, indicating that the numerical code, COUPLE, can be used to conduct the time-domain analysis of a truss spar interacting with its mooring and riser system under severe storm impact. A comparative study was also conducted to analyze the significance of interaction of risers with the hull structure. Three different cases of coupled analysis are simulated, namely (i) coupled analysis of truss spar interacting with mooring lines, (ii) coupled analysis of truss spar interacting with the mooring lines and the steel catenary risers, (iii) coupled analysis of truss spar interacting with the mooring lines, the steel catenary risers and top tension risers. Major statistical parameters of the global motions of the truss spar and the mooring line tensions for the three cases are compared with the field measurements.
|
2 |
Numerical simulation of the truss spar 'Horn Mountain' using COUPLETheckum Purath, Basil 16 August 2006 (has links)
A truss spar, named as Horn Mountain, was deployed in the Gulf of Mexico in 1,650 m of water, approximately 150 km southeast of New Orleans in June 2002. Horn Mountain is operated by British Petroleum (B.P.). Extensive field measurements were made using an integrated marine monitoring system attached to the truss spar. In this study, dynamic analysis of the truss spar interacting with its mooring and riser system was performed using a time-domain numerical code, known as ÂCOUPLEÂ. The simulated results were then compared with the corresponding field measurements made during Hurricane Isidore. During the numerical study, various hydrodynamic parameters which were crucial to the accuracy of predicting the global motions of the truss spar and tensions in mooring lines and risers were scrutinized, such as the drag and added-mass coefficients of heave plates, hard tank and truss beams. Satisfactory agreement between the simulation and corresponding measurements was reached, indicating that the numerical code, COUPLE, can be used to conduct the time-domain analysis of a truss spar interacting with its mooring and riser system under severe storm impact. A comparative study was also conducted to analyze the significance of interaction of risers with the hull structure. Three different cases of coupled analysis are simulated, namely (i) coupled analysis of truss spar interacting with mooring lines, (ii) coupled analysis of truss spar interacting with the mooring lines and the steel catenary risers, (iii) coupled analysis of truss spar interacting with the mooring lines, the steel catenary risers and top tension risers. Major statistical parameters of the global motions of the truss spar and the mooring line tensions for the three cases are compared with the field measurements.
|
3 |
Numerical Modeling of Nonlinear Coupling between Lines/Beams with Multiple Floating BodiesYang, Chan K. 2009 May 1900 (has links)
Nonlinear coupling problems between the multiple bodies or between the
mooring/riser and the offshore platform are incorporated in the CHARM3D-MultiBody,
a fully coupled time domain analysis program for multiple bodies with moorings and
risers. The nonlinear spring connection module and the three dimensional beam module
are added to appropriately solve the structural connection problem. The nonlinear spring
connection module includes the hydro-pneumatic tensioner module with the friction &
stick/slip implementation, the tendon/mooring disconnection (breakage/unlatch) module
with the tendon down-stroke check, and the contact spring with the initial gap with the
friction force implemented.
The nonlinear coupling may happen in many places for the offshore floating
structures, such as hydro-pneumatic tensioner, tendon of TLP down stroke at the bottom
joint, stick-slip phenomena at the tie down of the derrick and most of the fender-to-steel
or steel-to-steel contact problem with initial gap during the installation. The mooring/tendon broken and unlatch can be a nonlinear connection problem once the
transient mode is taken into account.
Nonlinearity of the stiffness and friction characteristics of the tensioner
combined with stick-slip behavior of riser keel joint is investigated. The relationship
between tensions and strokes for hydro-pneumatic tensioner is based on the ideal gas
equation where the isotropic gas constant can be varied to achieve an optimum stroke
design based on tensioner stiffness.
A transient effect of tendon down-stroke and disconnection on global
performance of ETLP for harsh environmental condition is also investigated by
incorporating the nonlinear boundary condition of the FE tendon model in CHARM3D.
The program is made to be capable of modeling the tendon disconnection both at the top
and the bottom connection as well as the down stroke behavior for the pinned bottom
joint.
The performance of the tie-down clamp of derrick is also investigated by using
six degrees of freedom spring model and the three(3) dimensional FE beam model. The
coupling of the TLP motion with the reaction force at the tie-down clamp is considered
by using exact nonlinear dynamic equations of the motion with the reaction forces
modeled with the spring or FE beam model. The method reduces too much conservatism
when we design the tie-down system by the conventional method, in which all the
environmental forces are combined without the phase lag effect between them. The FE beam model is also applied to the connectors between the
semisubmersible and the truss for the pre-service and in-place conditions to be verified
with the model test results, which shows good agreements.
|
4 |
A transient computational fluid dynamic study of a laboratory-sclale fluorine electrolysis cellPretorius, Ryno 07 December 2011 (has links)
Fluorine gas is produced industrially by electrolysing hydrogen fluoride in a potassium acid fluoride electrolyte. Fluorine is produced at the carbon anode, while hydrogen is produced at the mild-steel cathode. The fluorine produced has a wide range of uses, most notably in the nuclear industry where it is used to separate 235U and 238U. The South African Nuclear Energy Corporation (Necsa) is a producer of fluorine and requested an investigation into the hydrodynamics of their electrolysis cells as part of a larger national initiative to beneficiate more of South Africa’s large fluorspar deposits. Due to the extremely corrosive and toxic environment inside a typical fluorine electrolysis reactor, the fluid dynamics in the reactor are not understood well enough. The harsh conditions make detailed experimental investigation of the reactors extremely dangerous. The objective of this project is to construct a model that can accurately predict the physical processes involved in the production of fluorine gas. The results of the simulation will be compared to experimental results from tests done on a lab-scale reactor. A good correlation between reality and the simulacrum would mean engineers and designers can interrogate the inner operation of said reactors safely, effortlessly and economically. This contribution reports a time-dependent simulation of a fluorine-producing electrolysis reactor. COMSOL Multiphysics was used as a tool to construct a two dimensional model where the charge-, heat-, mass- and momentum transfer were fully coupled in one transient simulation. COMSOL is a finite element analysis software package. It enables the user to specify the dimensions of his/her investigation and specify a set of partial differential equations, boundary conditions and starting values. These equations can be coupled to ensure that the complex interaction between the various physical phenomena can be taken into account - an absolute necessity in a model as complex as this one. Results produced include a set of time dependent graphics where the charge-, heat-, mass- and momentum transfer inside the reactor and their development can be visualized clearly. The average liquid velocity in the reactor was also simulated and it was found that this value stabilises after around 90 s. The results of each transfer module are also shown at 100 s, where it is assumed that the simulation has achieved a quasi-steady state. The reactor, on which the model is based, is currently under construction and will be operated under the same conditions as specified in the model. The reactor, constructed of stainless steel, has a transparent side window through which both electrodes can clearly be seen. Thus the bubble formation and flow in the reactor can be studied effectively. Temperature will be measured with a set of thermocouples imbedded in PTFE throughout the reactor. The electric field will similarly be measured using electric induction probes. / Dissertation (MEng)--University of Pretoria, 2012. / Chemical Engineering / unrestricted
|
5 |
Visualizing and Interacting with Externally Coupled Engineering Analysis ResultsNelson, Paul Frederick 14 July 2005 (has links) (PDF)
Visualizing and interacting with engineering analysis results can provide valuable insights into a system's performance and aid in engineering decision-making. Currently, the majority of analysis codes are developed as isolated solutions focusing only on the most prominent physical influence to a system, such as thermal, structural, fluid, etc. Frequently, more than one of these physical influences combined to force engineers to evaluate complex, coupled systems. Coupled analysis codes are becoming more common place tools for engineers demanding high fidelity simulations of complex systems. External code coupling solutions are emerging to permit generic coupling of separate, world class CAE solvers thus providing a more general class of multidisciplinary simulations. The true value of an engineering analysis is determined by the accuracy of the analysis code and the ability to interpret all of the significant information contained in the analysis results. Post-processing visualization tools have long been valued for their ability to aid engineers in interpreting all of the significant information contained in non-coupled CAE analysis results. The tie between non-coupled CAE solvers and post-processing visualization tools is poorly defined and currently few general post-processing visualization tools exist capable of interpreting a wide range of differing CAE results. The few tools capable of general post-processing require extensive development of dozens of data readers or translators to accommodate the slew of varying CAE data formats. As coupled CAE solutions emerge, a need exists to standardize the data exchange between CAE solvers and post-processing visualization tools. A format for this standard CAE data exchange, similar to IGES for CAD/CAM data, is proposed. The object of this research is to bridge the gap between external code couplers and post-processing visualization tools to initiate visualization and interaction with these externally coupled results. This fusion of two dissimilar technologies affords a greater level of result interpretation to support engineering decision-making. A general integration architecture is presented and a proof of concept with industry leading tools is developed to demonstrate the benefits of a tight integration between external code couplers and post-processing visualization tools. Examples are presented of visualizing externally coupled results. This research lets the engineer significantly interact with and visualize more complex problems, solved in preferred world class tools, in a timely and streamlined manner.
|
6 |
SOIL-WATER COUPLED FINITE DEFORMATION ANALYSIS BASED ON A RATE-TYPE EQUATION OF MOTION INCORPORATING THE SYS CAM-CLAY MODELNAKANO, MASAKI, ASAOKA, AKIRA, NODA, TOSHIHIRO 12 1900 (has links)
No description available.
|
7 |
[en] GEOMECHANICAL EFFECTS ON PETROLEUM RESERVOIR SIMULATIONS / [pt] EFEITOS GEOMECÂNICOS NA SIMULAÇÃO DE RESERVATÓRIOS DE PETRÓLEOFLAVIA DE OLIVEIRA LIMA FALCAO 01 November 2002 (has links)
[pt] Simuladores de escoamento em reservatórios são ferramentas
importantes na otimização do desenvolvimento de um campo de
petróleo. Estes simuladores modelam o escoamento
multifásico através de meios porosos compressíveis, levando
em conta as equações de equilíbrio de fases, as leis de
fluxo e a variação volumétrica do meio poroso associada à
variação da pressão de poros do sistema. As tensões in situ
são consideradas através da aplicação de tensões constantes
no contorno do reservatório. Este trabalho descreve a
utilização de um simulador convencional de reservatório,
baseado em diferenças finitas com e sem um módulo
geomecânico, e a utilização de um simulador acoplado, que
resolve as equações de escoamento e de tensão num mesmo
código de elementos finitos. Nesta dissertação são feitas
comparações entre os modelos geomecânicos aproximado e
rigoroso oferecidos pelos simuladores comerciais, além de
ser apresentada uma análise de situações em que esta última
forma deve ser realmente considerada. O objetivo deste
trabalho é analisar a influência das tensões in situ em
reservatórios de petróleo com base na comparação entre
os campos de poropressões obtidos a partir da modelagem de
um mesmo sistema com os dois simuladores geomecânicos. São
apresentadas as formas de acoplamento e a formulação
utilizada em cada um dos modelos. Os modelos geomecânicos
utilizados em cada um dos simuladores são comparados. É
feita uma comparação entre os resultados obtidos pelos dois
simuladores a partir de um modelo bidimensional. / [en] Numerical simulators for reservoir flow analysis are
important tools for the
optimization of oil field development. These simulators
model the multiphase flow
through compressible porous medium taking into account the
phase equilibrium
equations, flow laws and the rock volumetric change
associated to the pore
pressure change during production. Some simulators have
been associated with
stress analysis modules in order to use the pore pressure
field obtained by the
flow simulator and update the stress field within the
reservoir. This dissertation
describes the use of a conventional reservoir simulator
based on finite
differences that models multiphase flow in porous media,
with and without a
geomechanical module, and the use of a fully-coupled
simulator that solves both
the flow and stress equations in a single finite element
code. This dissertation
compares the two geomechanical modules, the approximated
and the precise,
offered by commercial simulators, and analyses the
situations in which the
rigorous form should be considered, or not. The aim of this
dissertation is to
investigate the influence of in situ stresses in petroleum
reservoirs based on the
comparison of the pore pressure fields obtained from the
modeling of the same
system with both geomechanical simulators. The coupling and
formulation used
in each model are presented. The geomechanical models of
both simulators are
described. A comparison of the simulators is made using a
bidimensional model.
|
8 |
Numerical method for coupled analysis of Navier-Stokes and Darcy flows / ナビエストークス流れとダルシー流れに対する連成解析のための数値解析手法Arimoto, Shinichi 26 March 2018 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21151号 / 農博第2277号 / 新制||農||1059(附属図書館) / 学位論文||H30||N5125(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 村上 章, 教授 川島 茂人, 教授 藤原 正幸 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
|
9 |
Computational Study of Highway Bridges Structural Response Exposed to a Large Fire ExposureNahid, Mohammad N. 08 July 2015 (has links)
The exposure from a localized vehicle fire has been observed to produce excessive damage onto highway bridge structural elements including complete collapse of the infrastructure. The occurrence of a fire beneath a bridge can lead to significant economic expense and loss of service even if the bridge does not collapse. The focus of the current research is to assess and evaluate the effect of realistic localized fire exposures from vehicles on the bridge structural integrity and to guide future development of highway bridge design with improved fire resistance.
In this research, the bridge structural element response was predicted through a series of three loosely coupled analyses: fire analysis, thermal analysis, and structural analysis. Two different types of fire modeling methodologies were developed in this research and used to predict the thermo-structural response of bridge structural elements: one to model the non-uniform exposure due to a vehicle fire and another to predict response due to a standard uniform furnace exposure. The vehicle fire scenarios required coupling the computational fluid dynamics (CFD) code Fire Dynamics Simulator (FDS) with Abaqus while the furnace exposure scenarios were all done within Abaqus. Both methodologies were benchmarked against experimental data. Using the developed methodologies, simulations were initially performed to predict the thermo-structural response of a single steel girder-concrete deck composite assembly to different local, non-uniform fires and uniform standard furnace fire exposures. The steel girder-concrete deck composite assembly was selected since it is a common bridge design. Following this, a series of simulations were performed on unprotected highway bridges with multiple steel plate girders and steel tub girders subjected to localized fires. The analyses were used to evaluate the influence of a fire scenario on the bridge element response, identify the factors governing the failure of bridge structural elements subjected to a localized fire exposure, and provide guidance in the design of highway bridge structural elements against fire hazards.
This study demonstrates that girder geometry affected both the dynamics of the fire as well as the heat transfer to the bridge structural elements which resulted in a different structural response for the bridge. A heavy goods vehicle (heat release rate of 200 MW) and tanker fires (heat release rate of 300 MW) were predicted to cause the bridge to fail due to collapse, while smaller fires did not. The geometric features of the plate girders caused the girder elements to be exposed to higher heat fluxes from both sides of the girder resulting in collapse when exposed to a HGV fire. Conversely, the closed feature of the box girder does not allow the interior surfaces to be in direct contact with the flames and are only exposed to the internal reradiation from surfaces inside the girder. As a result, the single and double lane tub girder highway bridge structure does not fail due to a heavy goods vehicle fire exposure. / Ph. D.
|
10 |
Implementation Of Coupled Thermal And Structural Analysis Methods For Reinforced Concrete StructuresAlbostan, Utku 01 February 2013 (has links) (PDF)
Temperature gradient causes volume change (elongation/shortening) in concrete structures. If the movement of the structure is restrained, significant stresses may occur on the structure. These stresses may be so significant that they can cause considerable cracking at structural components of large concrete structures. Thus, during the design of a concrete structure, the actual temperature gradient in the structure should be obtained in order to compute the stress distribution on the structure due to thermal effects. This study focuses on the implementation of a solution procedure for coupled thermal and structural analysis with finite element method for such structures. For this purpose, first transient heat transfer analysis algorithm is implemented to compute the thermal gradient occurring inside the concrete structures. Then, the output of the thermal analysis is combined with the linear static solution algorithm to compute stresses due to temperature gradient. Several, 2D and 3D, finite elements having both structural and thermal analysis capabilities are developed. The performances of each finite element are investigated. As a case study, the top floor of two L-shaped reinforced concrete parking structure and office building are analyzed. Both structures are subjected to heat convection at top face of the slabs as ambient condition. The bottom face of the slab of the parking structure has the same thermal conditions as the top face whereas in the office building the temperature inside the building is fixed to 20 degrees. The differences in the stress distribution of the slabs and the internal forces of the vertical structural members are discussed.
|
Page generated in 0.1304 seconds