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Publication Abstracts Advanced Compututational Methods & Applications in Marine Technology COTech201:
CFD
Analysis in Subsea and Marine Technology Wikki
Ltd, London, United Kingdom Abstract._Computational
Fluid Dynamics (CFD) is established in design and analysis for a
range of industries, but its use in Marine and Naval Hydrodynamics is
behind the trend. This can be attributed to the complexity of
modelling needs, including presence of free surface, irregular
transient fluid-structure coupling and presence of established
modelling tools based on potential theory. In this paper,
state-of-the-art of CFD in Naval Hydrodynamics, wave and offshore
applications is given, with an update of recent advances, validation
and computing requirements for typical simulation cases. Keywords.
CFD,
Global performance, Green sea, Naval hydrodynamics, Sea-keeping, Wave
loads COTech202:
Multi-fluid
CFD analysis in Process Engineering
B H Hjertager Department
of Mechanical and Structural Engineering and Materials Science, Abstract.
An
overview of modelling and simulation of flow processes in
gas/particle and gas/liquid systems are presented.
Particular emphasis is given to computational fluid dynamics
(CFD) models that use the multi-dimensional multi-fluid techniques.
Turbulence modelling strategies for gas/particle flows based on the
kinetic theory for granular flows are given. Sub models for the
interfacial transfer processes and chemical kinetics modelling are
presented. Examples are shown for some gas/particle systems including
flow and chemical reaction in risers as well as gas/liquid systems
including bubble columns and stirred tanks. Keywords.
CFD,
Gas-liquid, Gas-particle, Multi-fluid, Multi-phase. COTech203:Accurate
green water loads calculation using naval hydro pack H
Jasak,
I Gatin, and V Vukčević Faculty
of Mechanical Engineering and Naval Architecture, University of
Zagreb, Croatia Abstract.
An
extensive verification and validation of Finite Volume based CFD
software Naval Hydro based on foam-extend is presented in this paper
for green water loads. Two—phase
numerical model with advanced methods for treating the free surface
is employed. Pressure loads on horizontal deck of a FPSO model are
compared to experimental results from [1] for three incident regular
waves. Pressure peaks and integrals of pressure in time are measured
on ten different locations on deck for each case. Pressure peaks and
integrals are evaluated as average values among the measured incident
wave periods, where periodic uncertainty is assessed for both
numerical and experimental results. Spatial and temporal
discretization refinement study is performed providing numerical
discretization uncertainties. Keywords.
Green
Water Loads, CFD, Regular Waves, VOF, Naval Hydro Pack Hui
Zhu*, Lin Li and Muk Chen Ong Department
of Mechanical and Structural Engineering and Materials Science Abstract.
This study
addresses numerical analysis of the installation of a tripod foundation
using a heavy lift vessel (HLV). Limiting sea states are firstly
predicted in the frequency domain based on crane tip vertical motions
using linear transfer functions. Then, numerical modelling and
simulations are carried out in the time domain to analyze the coupled
dynamic system taking into consideration of the nonlinearities of the
system. In time-domain analysis, two lifting phases are brought into
focus, i.e., the lift-off and the lowering phases. For the lift-off
phase, two scenarios are considered, i.e., lift-off from the own deck
of the HLV and lift-off from a transport barge. Moreover, comparative
studies using two types of installation vessels, a floating vessel
and a Jack-up, are investigated for the lowering process. Critical
responses including the motions of the tripod and the lift wire
tensions are presented and compared under various environmental and
loading conditions. Keywords:
Frequency domain analysis, Lift-off, Limiting sea states, Lowering,
Time domain analysis, COTech205:
Vortex-Induced
Vibration (VIV) Effects of a Drilling Riser Due to Vessel Motion Rohan
Shabu Joseph, Jungao Wang, Muk Chen Ong and Jasna B. Jakobsen Dept.
of Mechanical and Structural Engineering and Materials Science, Abstract.
A
marine riser undergoes oscillatory motion in water due to the vessel
motions, known as global
dynamic response. This to-and-fro motion of the riser will generate
an equivalent flow that can cause Vortex-Induced Vibrations (VIVs),
even in the absence of the ocean current. In the present work,
full-scale measurement
data of a drilling riser operating in
the Gulf of Mexico are analyzed. The VIV occurrences for the riser
are identified from the data and the possible excitation sources are
discussed. The oscillatory flow due to vessel motion is compared with
the ocean current and its possibility to excite VIV is analyzed. The
full-scale data analysis provides an insight into the vessel motion-induced VIV of marine risers in the actual
field environment. Keywords.
Full-scale
measurements, Oscillatory flow, Riser, Vessel motion, Vortex-induced
vibration COTech206:
Large
eddy simulation of the tidal power plant deep green using the
actuator line method S T Fredriksson1*,
G Broström1, M
Jansson2, H
Nilsson3, and B
Bergqvist2 1Department
of Marine Sciences. University of Gothenburg, Gothenburg, Sweden Abstract.
Tidal
energy has the potential to provide a substantial part of the
sustainable electric power generation. The tidal power plant
developed by Minesto, called Deep Green, is a novel technology using
a ‘flying’ kite with an attached turbine, moving at a speed
several times higher than the mean flow. Multiple Deep Green power
plants will eventually form arrays, which require knowledge of both
flow interactions between individual devices and how the array
influences the surrounding environment. The present study uses large
eddy simulations (LES) and an actuator line model (ALM) to analyze
the oscillating turbulent boundary layer flow in tidal currents
without and with a Deep Green power plant. We present the modeling
technique and preliminary results so far. Keywords.
Tidal
energy, Turbulence, Large Eddy Simulation (LES), Actuator Line Method
(ALM). COTech207:
Fluid
Flow in Steady and Oscillatory Lid-driven Square Cavities
Jianxun Zhu, Lars Erik Holmedal, Dag Myrhaug, Hong Wang Abstract. This paper presents numerical simulations of steady and
oscillatory lid-driven cavity flow at different Reynolds num- bers
with a fixed aspect ratio of 1:1. A projection method (P2 pressure
correction method) is applied to solve the incompressible
Navier-Stokes equations. The code is validated by comparison with
published works of steady lid-driven flow at Re = 100, 400 and 1000.
Oscillatory lid-driven cavity flow at different Reynolds numbers
(100, 400 and 1000) at a fixed oscillation frequency has been
investigated. It is observed that the oscillatory lid-driven cavity
flow is substantially affected by the Reynolds number. Keywords.
Navier-Stokes equation, oscillatory lid-driven cavity flow, projection
method, P2 pressure correction method, steady lid- driven cavity flow
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