Proceedings of the 11th International Conference

on Hydrodynamics (ICHD 2014)

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

Session Papers (101-120)

101.  Oil Recovery Enhancement via Different Gas Injection Scinarios in Fractured Reservoirs.

Y. M. Al-Wahaibi.

Petroleum and Chemical Engineering Department, Sultan Qaboos University, Muscat, Oman.

Abstract :

Experimentally measured recoveries, gas cuts and residual saturations were used to quantify the effects of different measurable system parameters on efficiency and gas/oil nonequilibrium of different multi-contact gas injection processes. The key finding in this work is the fact that the produced fluids in all the experiments werenot in equilibrium. This was observed in the displacements through the homogeneous porous medium as well asin the heterogeneous medium, suggesting that the lack of compositional equilibrium was not due to large-scale heterogeneity. Otherwise, the experimentally determined sweep efficiencies of the multi-contact miscible displacements were what would be expected: they were better in the homogeneous pack than in the heterogeneous pack and in the heterogeneous pack they were better than those of immiscible displacements but worse than those of first-contact miscible displacements.

102.  Dynamics of slurry setting during land reclamation.

T.T. Vu, F.J. Chua, H.S. Lim, J. He, S.K. Tan.

DHI-NTU Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, Singapore 637141.

Abstract :

A reclaimed land is formed by dumping/spreading or ‘rainbowing’ sediment on the seabed. In some cases, marine mud or soft dredged seabed material is used as landfill material. The softsoil is delivered to the target area using the “rainbow” method and the soft soil, in the form of slurry, flow to fill the target area. Dewatering of the slurry, particle size distribution and settlement of the particles are important considerations in assessing the soil strength of the reclaimed land. As a result, the amount of ground improvement work, including surcharge, would have to be designed and executed carefully to establish a stable reclaimed area and platform. To improve the efficiency ofa reclamation project using dredged seabed material as fill-material, the execution plan and design should consider not only how the soft soil particles settle, but also the filling process which should also be designed and carried out so that the soil and mud settle readily and build up to the desired elevation as soon as possible. The filling process, including the number of stages, water content of the slurry, and the duration of settlement of the soft soil are important parameters that will determine the potential speed of the reclamation process. This paper presents the preliminary results obtained from a series of laboratory studies on the settling process using the method of filling in stages and continuous filling underwater. The effects of such methods and conditions of filling on the settlementof soil particles, and the rate of settlement are compared with the current settling theory.

103.  Study on the Destruction of Tip Vortex Cavitation on Propeller of 13,000 TEU Class Container Vessel.

Sung-Han Chu, Sung-Hoon Kim, Gil-Hwan Choi.

Hyundai Maritime Research Institute, Hyundai Heavy Industries, Co., Ltd, Ulsan, 682-792, Korea.

Abstract :

The objective of this paper is to find out the detailed flow structure near propeller tip area and the reason of destruction at tip vortex cavitation of a propeller on a container vessel. Close observations have been carried out using a high speed video to understand detailed tip flow of a propeller which was hard to observe by using a stroboscope during model test. In numerical simulation, STAR-CCM+ is used to obtain a detailed flow behavior of tip vortex cavitation. The result of the numerical simulation corresponded well with the flow structure of the experiment. The vortical flow induced by re-entrant jet of the sheet cavitation gradually increases as it goes towards trailing edge. After passing trailing edge, the re-entrant jet occurring by the collapse of the sheet cavitation causes vortical flow stronger which leads to distortion at tip vortex cavitation.

104.  E-SEMI - Feasible Solution for Dry Tree Application in Deepwater.

Z.Y. Tay, A. Jain, Adrian Ke.

Keppel Offshore and Marine Technology Centre, 31 Shipyard Road, Singapore 628130.

Abstract :

This paper presents a feasible solution for dry tree application in deepwater drilling and production by using an Extended-draft SEMI-submersible (E-SEMI). The advantages of the E-SEMI over other floating systems are presented and their ability to accommodate the dry tree system for the use in deepwater is highlighted. The assembly sequence of the lower hull, quayside integration of the topside and lowering sequence of the second tier pontoon (STP) are presented and the technology and historical development of the E-SEMI from 2004 to the present date are also introduced. The laboratory test carried out in Lab Oceano, Rio De Janeiro is presented to demonstrate the controlled STP Lowering motion in offshore. Based on these model test data, an improved E-SEMI hull with radiated column is proposed and numerical hydrodynamic analysis are carried out to confirm the improvement in the hull motion in accordance to the DNV design criteria and 100-year extreme condition. Approval-in-Principle (AIP) letter has been issued by DNV stating that the E-SEMI as a feasible concept for Petrobras offshore Brazil ultra-deepwater development whereas ABS AIP concluded that the concept is feasible and is in compliance with the requirements in the ABS MODU Rules and FPI guide.

105.  Review of Riser Techniques for Deepwater Application.

H.D. Nguyen, Z.Y. Tay, B.A.P. Francis, V. Mihalev.

Keppel Offshore and Marine Technology Centre, 31 Shipyard Road, Singapore 628130.

Abstract :

Risers are of prime importance for offshore drilling and production developments. Recently oil and gas activities have moved into deeper water depths and high working pressure reservoir regions. This makes the design of riser systems more challenging. Riser system costs and operational envelops are particularly sensitive to the increases in water depths. A number of new riser techniques have been developed in recent years that could improve the operational performance and provide a cost effective solution. This paper presents an overview of recent developments of riser technology for deepwater applications. It highlights new techniques and key issues addressed during these developments including various effects of deepwater and high working pressure environments as compared to the conventional riser technology.

106.  Experimental Study on Live Load Dependent Hydrodynamic Behavior of Floating Body.

Y.J. Jeong, M.S. Park, D.H. Lee, Y.J. You.

Structural Engineering Research Division, Korea Institute of Civil Engineering & Building Technology, Goyang, Gyeonggi, 411-712, Republic of Korea.

Abstract :

In this study, in order to evaluate live load dependent hydrodynamic behaviors of the floating body, experimental studies were carried out for the small-scale pontoon models. At first, a small-scale pontoon model with scale factor 1:75 was fabricated and tested under the four cases of the wave loadings. Two live load cases were simulated using additional mass corresponding to the live load 0% (only floating body), fully live load cases onto the topside. Some gauges for the acceleration, displacement, and load were attached on the small-scale models and measured during the tests. Small-scale tests were carried out during the 420 sec, wave excitation test persisted during the 300 sec and the decay test after the wave excitation persisted during the 120 sec. Finally, based on the measured data, hydrodynamic motions of the pitch, surge, and drift force were evaluated and compared with each other. As the results of small-scale test, it was found that the pitch motion is more sensitive to the wave period than the surge and drift motions. As the results of small-scale test, it was found that the pitch motion is more sensitive to the wave period and surge motion is more sensitive to the wave height for the both live load cases of the live load 0% and fully live load case. As the live loads increase, the total weight also increase and the draft decreased. Therefore, as the live loads onto the topside increased, whereas hydrodynamic behaviors of the pitch motion reduced presenting nonlinearity, especially pitch acceleration reduced significantly, because of the increasing of the total weight, surge motion and drift force were increased because of the increasing of the draft and projection area for the wave force. Therefore, it is recommended that serviceability of the floating body should be checked for the only floating body case (not include live load) and mooring force should be checked for the fully live load case.

107.  Wind-assisted ship propulsion: A review and development of a performance prediction program for commercial ships.

G. Bordogna, D.J. Markey, R.H.M. Huijsmans, J.A. Keuning, F.V. Fossati.

Section of Ship Hydromechanics and Structures, Delft University of Technology, Mekelweg 2 Delft, 2628 CD, The Netherlands.

Abstract :

In this paper the state-of-the-art on wind-assisted propulsion for commercial ships is presented. The review shows that, albeit a considerable amount of research has been carried out over the years,   there is still a substantial lack of knowledge on the actual performance of wind-assisted ships. Especially the aerodynamic interaction effects of wind propulsion systems as well as the hydrodynamic phenomena heel, leeway, sideforce and yaw balance are often simplified or neglected. A performance prediction program is presented and it aims to be a versatile design tool tobetter evaluate the use of wind energy as an auxiliary form of propulsion for commercial ships.

108.  Investigation on three interacting pipe jets at inclination angle of 30 degree.

J.X. Zheng, S.K. Tan.

School of Civil and Environmental Engineering, Nanyang Technological University 50 Nanyang Avenue, Block N1-B1a-03, Singapore 639798.

Abstract :

This experimental study is on the fluid-dynamic features produced by a novel configuration of three circular pipe jets set at an inclined angle of 30° on the same plane and issued into a stationary receiving water. The investigation was conducted using a particle image velocimetry measurement technique. The results in terms of centreline maximum velocity decay and crosssectional velocity distribution on both the spanwise and the transverse plane were examined in details. The centreline maximum velocity decays linearly after a streamwise distance of 8.5D(diameter of the jet nozzle) from the nozzle. Self-similar profiles are attained certain distance downstream of the nozzle. Gaussian profile was found suitable for the profile on the spanwise plane and double peak profile was observed on transverse plane. The compound jets boundary edges observed based on the jet half width show linear profile on the X-Yplane and parabola curve on the X-Zplane. The growth rates of the velocity spreading width on both central planes are larger than those of a single pipe jet. Two pairs of counter-rotating vortexes were observed along the trajectory of the jet, between 12Dand 32D. The effect of initial momentum on flow development is not discernible after a streamwise distance of 27D, after which the effect of ambient fluid predominates.

109. Experimental Study of Cavitating Flow inside Diesel Nozzles with Different Length-Diameter Ratios Using Diesel and Biodiesel.

Zhuang Shao, Zhixia He, Qian Wang,Wenjun Zhong, Xicheng Tao.

School of Energy and Power Engineering, Jiangsu University, Zhenjiang, Jiangsu province, China,212013.

Abstract :

The complicated cavitating flow inside diesel nozzles has long been concentrated on, and cavitating flow characteristics of biodiesel in nozzles with different structures is instructive to the highly efficient use of biodiesel in diesel engines. In this paper, on the visualization experimental system with a transparent scaled-up injector nozzle tip and the high-speed digital camera were used to investigate the cavitating flow in transparent VCO nozzles with different length-diameter ratios (L/D) using diesel and biodiesel, and the energy loss in the occurrence of the hydraulic flip was also analyzed. Moreover, the nozzle cavitating flow characteristics were studied not only during the period of increasing of injection pressure but also decreasing of injection pressure. The hydraulic flip phenomenon occurred in nozzles with L/D of 4 and 6, but not appeared in nozzles with L/D of 8. The cavitation is easier to occur for the dieselthan for the biodiesel. The nozzle discharge coefficient for the diesel is higher than that for the biodiesel when the flow is single-phase turbulent flow, while it got much smaller for the diesel than that for the biodiesel when the cavitating flow and the hydraulic flip phenomenon occur. The critical numberof cavitation inception is smaller than that of cavitation disappearance.

110.  Investigation of the internal flow and spry characteristics from diesel nozzle with different needle shapes.

Liang Zhang, Zhixia He, Qian Wang, Shao Zhuang, Genmiao Guo.

School of Energy and Power Engineering, Jiangsu University, Zhenjiang, Jiangsu province, China.

Abstract :

The combustion and emission processes  are known to be effected by the fuel spray characteristics significantly in diesel engines. As high-pressure common-rail injection system is available and high injection pressure for getting better spray characteristics can enhance combustion efficiency and reduce emission. However, the spray mechanism under high fuel injection pressure becomes more and more complex which makes the study on atomization mechanism more challenging and difficult.  It has been known that the nozzle internal turbulent and cavitating flow influence the subsequent fuel  atomization process and  spray characteristics greatly.  And cavitation has been the key of connecting nozzle flow with atomization behavior. In this paper, firstly, a KH-RT coupled with the internal cavitaing flow spray model was setup and validated by the spray experimental data got from a high pressure common-rail injection experiment system.  The results showed that the cavitating flow characteristics in nozzles have a large effect on both spray penetration and sauter mean diameter of diesel spray.  Then, two different shapes of needle was designed  and its  effect  on  the  cavitation  flow  and  spray  characteristics  was  simulated  with  the  verified  KH-RT  coupled  with cavitation flow spray model. The numerical analysis results show that the fuel injected from high hole atomized well and has less penetration due to the serious internal flow cavitation.  Besides,  the nozzle  with  cylindrical  shape  of  needle  could  reduce  the cavitaion and produces larger SMD when compared with the nozzle with  conical  shape of needle. The research may supply a certain reference for structure optimization of the fuel nozzle.

111.  Transformation of representative wave heights using parametrical wave approach.

W. RATTANAPITIKON, N. T. DUONG.

Civil Engineering Program, Sirindhorn International Institute of Technology, Thammasat University, Pathum Thani 12121, Thailand.

Abstract :

The representative wave heights are one of the most essential parameters required for the study of coastal processes and the design of coastal structures. The present study focuses on the transformation of four representative wave heights (i.e. mean wave height (Hm), root-mean-square wave height (Hrms), highest one-third wave height (H1/3 ), and highest one-tenth wave height (H1/10 )) by using a parametric wave approach. The parametric wave approach is a widely used for computing the transformation of rms H, especially in commercial or free software. It would be useful for practical work, if this approach could be used to compute other representative wave heights. Nevertheless, it seems that no literature has pointed out that the parametric wave approach is applicable for computing m H, H1/3 , and H1/10 . Hence, the present study was carried out to examine the possibility of simulating the representative wave heights (Hm , Hrms , H1/3 , and H1/10 ) transformation across-shore by using the parametric wave models. Eleven parametric wave models were selected to examine the applicability. Laboratory data from small scale and large-scale wave flumes were used to calibrate and examine the models. The examination showed that most models (with new coefficients) could be used to compute the transformation of the representative wave heights with very good accuracy. The top three models are recommended to use for computing the transformation of representative wave heights.

112.  Numerical simulation of the energy dissipation failure of the aqueduct free overfall.

Li Yalin, Yuan Shouqi, Mao Jieyun, Tan Soon Keat, Wang Xikun.

Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang, 212013, China.

Abstract :

The water-air two-phase free overfall of the aqueduct was calculated by the homogeneous flow model and SST k–ω turbulent model. And the free surface model was applied to track the complex water-air interface of the aqueduct, step and rapid filter channel. The flow fields of free overfall, water surface profile, filter flows, energy dissipation rate, and other related hydraulic parameters were obtained. Then the filter flows affected by the free overfall of rectangular aqueduct were compared with that of round aqueduct. And the reason of the energy dissipation failure ofthe aqueduct free overfall was analyzed from the aspect of the inside flow pattern. The results indicated that the flow disturbance intensity and spread was significantly affected by the structure of steps. And the main reason causing 1stfilter flow decrease was that the flow had higher kinetic energy after round aqueduct step. The simulated filter flows were in good agreement with the data obtained in experiment to verify the feasibility of the mathematical model. Furthermore, it also could provide much important data for engineering design and optimize.

113.  Airgap Calculation and the Effects of Wave Diffraction and Higher Order Waves.

Xiaoming Cheng, Bo Wu.

China Ship Scientific Research Centre, Wuxi, 214082 China。

Abstract :

Airgap  is  an  important  design  factor  for  offshore  platforms,  either  fixed  or  floating,  as  a  negative  airgap  can  result  in  wave slamming on the platform deck, causing structural damage and even loss of life. The industrial practice for the airgap calculation is usually to perform the platform motion analysis in frequency domain or time domain and find the min imum relative vertical clearance between the points of interest on the platform and the wave surface below these points. Compared with the frequency domain method, the time domain method can handle nonlinear problems more effectively and is widely used in the platform motion and mooring analysis.  However if the effect of the diffracted and radiated wave surface  is  to be considered in the  airgap calculation, only the frequency domain method  is used in practice, the  airgap  calculated in  the time domain is always relative to the undisturbed wave surface. This is due to the practical difficulties in assessing the diffracted and radiated wave surface for a moving structure at every time step.  This paper proposes a combined method for the airgap calculation.  The main feature of this method is to calculate the airgap relative to the undisturbed linear wave surface in time domain, and then assess in frequency domain the effect of the diffracted and radiated wave surface on the airgap which is used to modify the time domain airgap. In addition, the effect of the higher order undisturbed wave surface is also assessed and included in the airgap modification. The details of this new method are presented in this paper together with a calculation example for a semi-submersible. The results show that using the proposed method the predicted airgaps at some critical  locations can be significantly worse than those calculated using traditional methods.

114. The High-Order Path-Conservative Scheme for A Saurel-Abgrall Model of Compressible NonConservative Two-Phase Flow.

Y.L. Jia, B.L. Tian, S. Jiang, E.F. Toro.

Institute of Applied Physics andComputational Mathematics, Beijing, 100094, China.

Abstract :

The Saurel-Abgrall model for two-phase flow in non-conservative form is studied. The Riemann solver is presented under the assumption that all the nonlinear waves are shocks. It then utilized to construct a high-order path-conservative scheme for numerical solution of the general initial boundary value problem via the MUSCL reconstruction and the Runge-Kutta technique, based on the 4-shock Riemann solver. Numerical results demonstrate the accuracy and robustness of our scheme in the numerical solution of the five-equation model for two-phase flow.

115.  An operational approach for the estimation of a ship’s fuel consumption.

N. Bialystocki, D. Konovessis.

Technical Department, Antares Shipping Ltd., 2 Haetgar Street, Tirat Carmel 39032, Israel.

Abstract :

When fuel efficiency is at stake, along with the reduction of the environmental foot print of air pollution, a need is presented to estimate a ship's fuel consumption for a forthcoming voyage, and means for decision making and for cost saving. This paper suggests an operational approach for obtaining an accurate fuel consumption and speed curve, on the basis of major factors affecting it, namely, ship's draft and displacement, weather force and direction, hull and propeller roughness. A statistical analysis on 418 noon reports of a Pure Car and Truck Carrier case ship is carried out and the influence of the above factors is calculated. As expected, stronger wind and head weather increases the fuel consumption, and the difference between several weather conditions could be quantified. A simple and accurate algorithm is proposed in order for ship owners, managers and operators to be in a position to apply the suggested method on their fleet.

116.  Nonlinear Dynamic Analysis of SCR with Effects of Hysteretic Seabed.

Chao Xu, Gang Ma, Lixin Xu, Liping Sun.

Deepwater Engineering Research Center, Harbin Engineering University, Harbin, 150001, China.

Abstract :

The interaction between riser and seabed involves a number of complex nonlinear factors, such as trench formation, nonlinear soil stiffness, soil suction, and the coupling of riser and soil movements. Both linear and nonlinear springs have been used to simulate the seabed, but they do not account for the effects of the soil suction and trench formation. The interaction between riser and soil has been divided into loading and unloading based on P-y curve model accounting for soil properties and trench formation. Therefore, a nonlinear hysteretic seabed model containing backbone curve and bounding loop was proposed in this paper. A steel riser with the length of 2226m has been analyzed with the OrcaFlex package. It found that the maximum Von Mises Stress and the maximum bend moment are near the touchdown point, and the TDZ (Touchdown Zone) responses resulted in the degradation of the seabed soil stiffness due to cyclic loading. Furthermore, soil resistance and riser penetration have significant effects on riser dynamic response.

117.  Steadily translating Green function withviscosity and surface tension effects.

H. Liang, X.B. Chen, Z. Zong, L. Sun.

Department of Naval Architecture Engineering, Dalian University of Technology, Dalian, 116024, China.

Abstract :

A translating Green function including the viscosity and surface tension effects is proposed. Based on the linearized free-surface boundary condition with the viscosity and surface tension effects, the Green function for a 3D Kelvin source in an analytical form is first derived. Then, an asymptotic analysis is made to study features of the dispersion relation and dispersion curves. Finally, an efficient and accurate technique is described for computing both local and wave components of the Green function. Furthermore, this Green function is used to study the wave-making problem of a Wigley hull. It is shown that not only can effects of viscosity and surface tension eliminate non-physical short waves, but also solve the singular problem of the wave component adequately.

118.  Vibration response analysis of an underwater submersible.

J.G. Sun, M.S. Zou.

China Ship Scientific Research Center, No.222, East Shanshui Road, Wuxi, Jiangsu 214082, China.

Abstract :

In this work, the vibration response characteristic of a type ofsubmersible structure sailing underwater is investigated based on the theory of three-dimensional hydroelasticity. The corresponding relationship between resonant frequencies of a submersible structure in vacuum and in water is obtained by figuring out both the responses at each of the principal coordinates and the hydrodynamic inertia corresponding to each mode of the dry hull. And the resonant frequencies of calculated response curves are well confirmed by the data from the acoustic test, illustrating that the three-dimensional hydroelasticity method is efficient to solve the vibration response of an underwater structure in manyengineering projects. Moreover, it attempts to improve the stern structure for vibration reduction, and the vibration response curves of submersible structure before and after the improvement measure are compared, it can conclude from the comparison that to reinforce the after main longitudinal structure members can effectively restrain the vibration on the stern structure of a submersible.

119.  Experimental and numerical analysis of two-dimensional steady-state sloshing in a rectangular tank equipped with a slatted screen.

R. Firoozkooh, O.M. Faltinsen.

MARINTEK, Trondheim,7052,Norway.

Abstract :

Effect of a slatted screen on resonant sloshing is studied using new experimental results and numerical computations. The tank is narrow for the sake of two-dimensional flow, and rectangular, and follows a sinusoidal forced horizontal motion. The screen is installed in the middle of the tank and the solidity ratio (ratio between solid area of the screen and its total area) of the screen is varied between 0.5 and 1. The forcing amplitude is small and the forcing  frequencies cover the first three natural frequencies of sloshing in the clean tank (tank without screen). An open source CFD (Computational Fluid Dynamics) code called OpenFOAM is challenged against the experiments to assess its ability in capturing nonli near free-surface effects in shallow water in presence of the screen. The numerical results are fairly good near the primary sloshing resonant frequencies. An important effect is the secondary resonance of the higher modes of sloshing which are more pronounced due to  the presence of the screen. These resonant effects that are away from primary resonant frequencies are shown to be captured by the numerical simulations both in terms of the  resonant frequency and amplitude of the sloshing wave responses at the vertical end-walls.  In the numerical simulations, the screen’s geometry is not simplified and all geometrical details are included.

200  Methodology for the ship to ship hydrodynamic interaction investigation applying the CFD Methods.

A.A. Zubova, D.V. Nikushchenko.

State Marine Technical University, Lotsmanskaya str.3, Saint-Petersburg, 190008, Russia.

Abstract :

Ship to ship interaction appears to be a challenging problem from the several aspects:  maritime practice, scientific research, engineering approaches and finally marine simulators implementation as a combination of previously named ones. Interaction forces  prediction  has been appearing in many researches during past times and still takes attention in  conditions  of growing marine traffic and port operation rules. But mainly researches performed in previous years are diverse, varying in objectives, showing a numerous variety of approaches. Building a unified strategy for the ship to ship interaction phenomena comprehension would be helpful for, on one side prediction methods, and on the other side experimental programs together with the practical studies somehow. The main objective of hereby presented studies was to validate the Computational Fluid Dynamics (CFD) available facilities towards the hydrodynamic forces and moments prediction in case of ship to ship interaction for the infinite fluid condition. Investigated conditions are reproducing the situation of the overtaking maneuver in general.