Proceedings of the 11th International Conference

on Hydrodynamics (ICHD 2014)

October 19 – 24, 2014,Singapore
Editors: TAN Soon Keat, WANG Xikun, GHO Wie Min & Joy CHUA

Keynotes

1.  Hydrodynamics of marine and offshore structures

O. M. Faltinsen.

Centre for Autonomous Marine Operations and Systems (AMOS), Department of Marine Technology, NTNU, NO-7491Trondheim, Norway.

Abstract :

An overview of hydrodynamic problems related to the broad variety of ships and sea structures involved in transportation, oil and gas exploration and production, marine operations, recovery of oil-spill, renewable energy, infrastructure and aquaculture is given. An approximate hydroelastic model for wave and current induced response of a floating fishfarm with circular plastic collar and net cage is discussed. Weakly nonlinear potential-flow problems such as slow-drift motions and stationkeeping, springing of ships and ringing are given special attention. Body-fixed coordinate system is recommended in weakly nonlinear potential-flow analysis of bodies with sharpcorners. Dynamic ship instabilities, Mathieu-type instabilities, chaos and two-phase flow involving interface instabilities are discussed. It is advocated that slamming must be coupled withstructural mechanics in order to find important time scales of the many physical effects associated with slamming and that both water entry and exit matter in describing the global wetdeck slamming effects. Further, sloshinginduced slamming in prismatic LNG tanks is perhaps the most  complicated slamming problem because many fluid mechanic and thermodynamic parameters as well as hydroelasticity may matter.

<

2.  Recent progress in CFD studies associated with naval architecture and ocean engineering

Frederick Stern, Zhaoyuan Wang, Jianming Yang, etc.

IIHR-Hydroscience and Engineering, University of Iowa, Iowa City, IA, USA.

Abstract :

An overview is provided of CFD Ship-Iowa modeling, numerical methods and HPC, including both current V4.5 & V5.5 and next generation V6. Examples for naval architecture highlight capability and needs.  High fidelity V6 simulations for ocean engineering and fundamental physics describe increased resolution for analysis of physics of fluids. Uncertainty quantification research is overviewed as first step towards development stochastic optimization.

3.  Environmental hydraulics of chlorine disinfection for the Hong Kong Harbour Area Treatment Scheme

Joseph Hun-Wei Lee.

Hong Kong University of Science and Technology, Hong Kong.

Abstract :

The Hong Kong Harbour Area Treatment Scheme (HATS) consists of a 24 kmlong deep tunnel sewerage system that collects and conveys sewage from the urban areas of Hong Kong to a centralized sewage treatment plant at Stonecutters Island since 2001. A sewage flow of 1.4 million m3/d receives Chemically Enhanced Primary Treatment (CEPT) followed by discharge through a 1.2 km outfall in the western Victoria Harbour. In order to protect the nearby marine beaches, chlorination facilities havebeen put into operation toprovide disinfection to the treated sewage since 2010. Sodium hypochlorite solution is injected at high concentrations in the form of multiple dense jets (relative density 1.2) into the sewage cross flow in a flow distribution chamber (FDC). The mixing and transport of chlorine in the FDC and the downstream chlorine contact culverts, and the complex chemical consumption of chlorine under different conditions play important roles in determining the sewage effluent quality. The disinfection operation has brought aboutsignificant improvements to the marine water quality in Victoria Harbour. While chlorine is an effective disinfectant for reducing pathogen levels, it is also toxic to aquatic life. There are also concerns with optimal chlorine dosage control which will help minimize environmental impact, and reduce energy consumption and operation cost. The lecture will highlight two aspects of the fluid mechanics of disinfection dosage control in a modern wastewater treatment and disposal system: (i) the fluid mechanics of dense jets including the internal hydraulics of the chlorine dosing units; and (ii) the predicted impact and field validation of different effluent discharge standards on beach water quality by the WATERMAN real time forecast system.

4.  Multi-physics and multi-scale modeling for eco-environmental characteristics of coastal water

J.H. Tao.

Dept. of Mechanics, Tianjin University, Tianjin, 300072, China.

Abstract :

Deal with the hydrodynamic and ecosystem characteristics of Bohai Bay, the numerical method (CFD) has been used to simulate the hydrodynamic characteristics and establish sub-model. For the marine ecological processes, two sub-models of ecosystem have been carried out. The first one is deterministic ecosystem sub-model, which is based on measurements and experimental method. The second one is non-deterministic ecosystem sub-models, the hybrid soft computing ANFIS-GA and CA-SVM have been used. Coupling the hydrodynamic sub-module and the ecosystem sub-module, the concentration of chlorophyll a has been simulated, which canbe estimator of phytoplankton biomass.

5.  Catastrophic Tsunamis and hurricanes in the last decade

Philip L.-F. Liu, Patricio Winckler Grez.

School of Civil and Environmental Engineering,Cornell University, Ithaca, NY 14853, USA, Institute of Hydrological and Oceanic Sciences, NationalCentral University, Jhongli, Taoyuan 320, Taiwan.

Abstract :

In this talk we will first summarize several most catastrophic tsunamis and hurricanes events inthe last decade. The physical characteristics of these events and their impacts are reviewed. We will discuss the similarities and dissimilarities between these two natural phenomena. Finally, existing numerical models for simulating tsunami and storm surge generation, propagation, and coastal inundation will be briefly discussed, which, however, are not included inthis extended abstract.

6.  Development and applications of the homotopy analysis method.

Shijun Liao. S. K. Tan.

State Key Laboratoryof Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiaotong University, Shanghai 200240, China.

Abstract :

In this talk, we briefly introduce the basic ideas and its applications of the homotopy analysis method (HAM), an analytic technique for highly nonlinear problems in science and engineering.  Compared to other analytic methods, the HAM has manyadvantages. First, based  on  the  homotopy  in  topology,  the  HAM  is  independent  of  any  small/large  physical parameters  and  thus  is  valid  for  more  of  nonlinear  problems.  Secondly,  unlike  all  other  analytic  methods,  the  HAM provides us a simple way to guarantee the convergence of solution series, so that it is valid in essence for highly nonlinear problems.   Third,  the  HAM  provides  us  great  freedom  to  choose  equation-type  of  high-order  equationsso that approximations  at  rather  high-order  can  be  obtained  easily.   Finally,  the  HAM  logicallycontainssome other nonperturbation techniques so that it is more general.Due to these advantages, the HAM can be successfully applied to solve lots of nonlinear problems better and/or in an easier way. Especially, like all truly new methods, the HAM can indeed provide us something new and/or different, as illustrated by a few examples here. 

7.  Two ISPH modeling techniques in hydrodynamics: coastal and river simulations

X. Liu, R. D. Chen, P. Z. Lin, S. D. Shao, S. K. Tan.

State Key Laboratory of Hydraulics and Mountain River Engineering,
Sichuan University, Chengdu, 610065, China.

Abstract :

In this keynote address, we will present the recent development of Incompressible Smoothed Particle Hydrodynamics (ISPH) modeling technique in different hydrodynamic fields. Since the start-up of ISPH modeling concept by Cummins and Rudman [1], the density-invariant ISPH was proposed by Shao and Lo [2] and velocity divergence-free ISPH was proposed by Hu and Adams [3] and Lee et al.[4]. The ISPH has played an important role in the SPH field due to its robust solution algorithm, although we have to agree that significant improvement has to be made to overcome certain issues for which the standard Weakly Compressible SPH (WCSPH) could perform better. Here we willpresent two latest ISPH algorithm developments and their promising applications in the coastal and river engineering, including the fluid-structure interactions and shallow water flows. These works have been carried out jointly with the Sichuan University.

8.  Non-spherical multi-oscillations of a bubble in a compressible liquid

Q. X. Wang, Y. X. Yang, D. S. Tan, S. K. Tan.

School of Mathematics, the University of Birmingham, Birmingham B15 2TT, United Kingdom.

Abstract :

Bubble dynamics (cavitation erosion) are associated with wide and important applications in many industrial systems, medical ultrasonics and underwater explosions. Two developments have been carried out for this classical problem. Firstly, computational studies on the problem have commonly been based on an incompressible fluid model. Consequently, a bubble usually undergoes significantly damped oscillation, which is due to neglecting the essential compressible effects. We model this phenomenon using weakly compressible theory and a modified boundary integral method. This model considers the energy loss due to shock waves emitted at minimum bubble volumes during the early expansion phaseand towards the end of the collapse phase. Secondly, the computational studies so far have largely beenconcerned with the first-cycle of oscillation.However, a bubble usually oscillates for a few cycles before it breaks into much smaller ones. We model both the first- and second-cycles of oscillation.It predicts damped oscillations, where both the maximum bubble radius and oscillation period reduce significantly from the first- to secondcycles of oscillation. Our computations correlate well with the experimental data for both the first- and second-cycles of oscillation.