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An Experimental Study on Friction Reduction by Additives in a Water Channel
Kim Wu-Joan,Kim Hyoung-Tae The Society of Naval Architects of Korea 2005 Journal of ship and ocean technology Vol.9 No.1
An experimental study has been carried out as a basic research for the development of the friction drag reduction technology for water-borne vehicles by injecting microbubbles or polymer solution. Experimental apparatus and procedures have been devised and prepared to measure the changes of the wall friction with the injection of additives and the basic experimental data on friction drag reduction are obtained for fully developed channel flows. The effects of key controlling parameters were investigated for higher drag reduction with varying the concentration and the injection rate of additives. The frictional drag has been reduced up to $25\%$ with the microbubble injection and $50\%$ with the polymer solution injection.
The Application of CFD for Ship Design
Kim, Wu-Joan 국립7개대학공동논문집간행위원회 2002 공업기술연구 Vol.2 No.-
The issues associated with the application of CFD for ship design are addressed. It is quite certain that the CFD tools are very useful in evaluating hull forms a prior to traditional towing tank tests. However, the time-consuming pre-processing is an obstacle in the daily application of CFD tools to improve hull forms. The accuracy of computational modeling without sacrificing the usability of CFD system is also to be assessed. The wave generation is still predicted by using potential panel methods, while velocity profiles entering into propeller plane is solved using turbulent flow solvers. The experimental data for CFD validation are invaluable to improve physical and numerical modeling. Other applications of CFD for ship design than hull form improvement are also given. It is certain that CFD can be a cost-effective tool for the design of new and better ships.
An Experimental and Computational Study on the Flow around a Hydrofoil with a Free-Surface
Kim, Wu-Joan,Van, Suak-Ho 대한조선학회 1995 Journal of hydrospace technology Vol.1 No.2
An experimental and computational study is carried out to investigate the flow characteristics around a hydrofoil when free surface presents. In the experimental study a NACA 0012 section is towed in a 2-D flume to document the wave profiles and surface pressure distribution. In the computational study a finite-difference scheme is employed to solve the Wavier-Stokes equations and free surface profiles are obtained directly from the kinematic boundary condition. The calculated results are compared with those of the present and other two experiments to confirm the capability of the present method in free surface problems. The agreement between calculation and measurement is very good. It is found that the pressure on the upper(suction) side of the fail does not drop as much as in deeply submerged case and the lift deceases as a result.
Report on the Cooperative Experimental Study Program
Kim, Hun-Chol,Yang, Seung-Il,Lee, Seung-Hee,Kim, Eun-Chan,Kang, Kuk-Jin,Lee, Young-Gill,Kim, Yoon-Ho,Lee, Kwi-Joo,Kwak, Young-Ki,Joa, Soon-Won,Kim, Hyo-Chul,Van, Suak-Ho,Kim, Wu-Joan,Song, Mu-Seok,Cho 대한조선학회 1987 大韓造船學會誌 Vol.24 No.3
The present paper describes the results of the cooperative experimental study organized by the Resistance Committee of the Korea Towing Tank Conference, which aims to improve model testing technique and accuracy and to self-evaluate their own capabilities. A Series 60, $C_b=0.60$ model was tested at the towing tanks of Korea Institute of Machinery & Metals, Hyundai Maritime Research Institute, Seoul National University, and Inha University. Results for total resistance, wave pattern analysis, wave pattern analysis, wave profile, trim & sinkage and wake measure ments are presented.
The Effects of Mean-Line Shape on Longitudinal Stablility of a Wing in Ground Effect
Kim, Wu-Joan,Shin, Myung-Soo The Society of Naval Architects of Korea 1996 Journal of hydrospace technology Vol.2 No.2
The Reynolds-averaged Navier-Stokes equations for turbulent flow around a two-dimensional foil section moving ova. a flat surface (roller plate) is solved. The numerical method utilized the finite-difference schemes in collocated grids and the Baldwin-Lomax model is employed for turbulence closure. Calculations are carried out for three foil sections of different mean-line shape with various height ratio. As a foil approaches the bottom surface, the lift is augmented, while there exist some differences in pitching moment due to mean-line shape. It was found that the S-shaped mean line deteriorates lift characteristics but increases pitching moment to restore the designed height.
Comparison of Turbulence Models for the Prediction of Wakes around VLCC Hull Forms
Kim, Wu-Joan,Kim, Do-Hyun,Van, Suak-Ho The Society of Naval Architects of Korea 2001 Journal of ship and ocean technology Vol.5 No.2
Turbulent flow calculations are performed for the two modern practical VLCCs with the sable forebody and the slightly different afterbody, i.e. KVLCC and KVLCC2. Three $\textsc{k}-\varepsilon$ turbulence models are tested to investigate the differences caused by the turbulence models. The calculated results around the two VLCC hull forms using O-O grid topology and profile-fitted surface meshes are compared to the measured data from towing tank experiment. The realizable $\textsc{k}-\varepsilon$model provided realistic wake distribution with hook-like shape, while the standard and RNG-based $\textsc{k}-\varepsilon$models failed. It is very encouraging to see that the CFD with relatively simple turbulence closure can tell the difference quantitatively as well as qualitatively for the two hull forms with stern frameline modification.
Development of Wave and Viscous Flow Analysis System for Computational Evaluation of Hull Forms
Kim, Wu-Joan,Kim, Do-Hyun,Van, Suak-Ho The Society of Naval Architects of Korea 2000 Journal of ship and ocean technology Vol.4 No.3
A computational system for wave and viscous flow analysis (WAVIS) has been developed. The system includes a pre-processor, flow solvers and a post-processor. The pre-processor is composed of full form presentation, surface mesh and field grid generation. The flow solvers are for potential and viscous flow calculation. The post-processor has graphic utility for result analysis. All the programs are integrated in a GUI-launcher package. To validate the developed CFD programs of WAVIS, the calculated results for modern commercial hull forms are compared with measurements. It is found that the results from WAVIS are in good agreement with the experimental data, illustrating the accuracy of the numerical methods employed for WAVIS.