SJTU-Ifremer Seminar on Problems and Methodologies for Characterization of Wave-Current Interactions

发布日期🔢：2011-11-01

报告题目

时间

2011-11-16 10:00

地点

Room A1008, Mulan NAOCE Building, Minhang Campus,Shanghai Jiao Tong University

报告人

SJTU-Ifremer

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联系人👨‍👩‍👦：

Date: 16th November 2011 (Wednesday)
Time: AM 10:00 – 16:00
Venue: Room A1008, Mulan NAOCE Building, Minhang Campus,
Shanghai Jiao Tong University
Program
1000-1030 Introducing wave action in forecasting of drift trajectories of
objects lost at sea. By Christophe Maisondieu (IFREMER)
1030-1100 Research and Development of Circulating Water Channel,
By Zuogang Chen (SJTU)
1100-1130 Discussions I
1130-1300 Lunch
1300-1330 Lab Tour (Deep Water Offshore Basin)
1330-1400 Alteration of sea-states by tidal currents. By Christophe
Maisondieu (IFREMER)
1400-1430 Features of the current generating system and its application
in the new deepwater offshore basin, By Haining Lv (SJTU)
1430-1500 Ifremer's new wave-current experimental facility. By Jérémy
Ohana (IFREMER)
1500-1530 Numerical simulation on nonlinear evolution of rogue waves
on currents, By Hanhong Hu (SJTU)
1530-1600 Discussions II
Abstracts
Research and Development of Circulating Water Channel
Zuogang Chen (SJTU)
The utility of Circulating Water Channel (CWC) is reviewed. To explore the flow
mechanisms and optimize the design of CWC, some common problems are
investigated by CFD method. In the computation, almost all components inside
CWC are taken into account. The interaction between the impeller and other
components are simulated to explore the influence of the swirling flow. Volume of
fluid method (VOF) is used to model the free surface flow at the test section. The
characteristic of the versatile CWC being built in Shanghai Jiao Tong University is
introduced. The study on the versatile CWC is carried out. The future research topic
in CWC is put forward.
Features of the Current Generating System and Its Application in the New
Deepwater Offshore Basin
Haining Lv (SJTU)
Modeling of the ocean current in the deepwater offshore basin will have significant
effect on the measured mooring loads and motions of the floating platforms. Constant
and stable flow field is required to be achieved during the offshore model tests.
During the presentation, features of current generating system in deepwater will be
introduced. The above system has been applied to the state-of-the-art deepwater
offshore basin of Shanghai Jiao Tong University. As the latest application, external
current recirculation and independent layers in vertical distribution have been applied.
Hydraulic performances of the new current generating system have been studied using
different methods, including CFD calculation, model tests and full scale
measurements. Current uniformities, turbulence levels and various vertical current
profiles etc. in measuring area are investigated accordingly. Results show that the
satisfactory performances can be achieved. Uniform and constant current flows with
low turbulence levels are produced with various current velocities. Typical vertical
current profiles, including uniform and stratified current profiles can be generated in
measuring area with good agreements with the target profiles.
Numerical Simulation on Nonlinear Evolution of Rogue Waves on Currents
Hanhong Hu and Ning Ma
Numerical simulations on nonlinear instability and evolution of deep-water rogue
waves on following and opposing currents had been studied. The generation of rogue
waves in a numerical tank by means of wave focusing technique is described. Here a
spatial domain model of current modified nonlinear Schrödinger (CMNLSC)
equations in one horizontal dimension was established for describing the deep-water
wave trains in a prescribed stationary current field. The transient water waves (TWW)
were adopted as the initial condition of the CMNLSC equation. The steady current
was added to investigate the effect of wave-current interaction on the energy
concentration of gravity waves. The influence of current on wave height, inclination,
particle velocity and acceleration are shown accordingly. Meanwhile, the focusing
time/position of TWW influenced by the current field is also investigated, which is of
course a very important factor in experiments when we generate rogue waves by
means of TWW. Besides, the preliminary work on surface wave generation in current
using CFD method was also shown.
Introducing wave action in forecasting of drift trajectories of objects lost at sea
Christophe Maisondieu
Drift forecast models used by authorities for search and rescue operations are mostly
based on the Leeway approach. In the Leeway method drift properties of different
classes of objects are experimentally assessed considering a combined action of wind
and waves.
In order to improve the quality of these drift models, it is of importance to
characterize the contribution of waves only. Theoretical background of wave action
for drift is investigated. Experiments are conducted in a wave tank for different kinds
of objects in order to validate the theoretical formulations. Finally results are
compared with data obtained from trials conducted on real size objects at sea.
Alteration of sea-states by tidal currents.
Christophe Maisondieu
We consider here the problematic of wave-current interactions for the design of
Marine Energy Converters. Requirements for MEC design are briefly presented.
Analysis of various measurement data sets are presented to point out the influence of
wave-current interactions on time evolution of sea-states parameters.
Introduction to Ifremer hydrodynamics facilities :
Jérémy Ohana
In this technical presentation you will be introduced to Ifremer wave tank, towing
tank and current flume. In order to have more realistic experimental conditions, these
facilities have been upgraded recently. A wind generator is now available on the wave
tank and current flume has now a wave generator. Some measurements and
experimental set up will also be shown