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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Visualization
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Journal DOI :
The Korean Society of Visualization
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Volume & Issues
Volume 2, Issue 2 - Dec 2004
Volume 2, Issue 1 - Aug 2004
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Visualization of Aerodynamic Noise using Computational Aeroacoustics
Lee Duck Joo ; Kim Jae Wook ; Lee In Cheol ;
Journal of the Korean Society of Visualization, volume 2, issue 2, 2004, Pages 3~7
In this paper, computational aeroacoustics (CAA) method is used for flow-noise analysis and flow-noise visualization. High order high resolution scheme of optimized high order compact is used to resolve the small acoustic quantities and large flow quantities at the same time. An adaptive nonlinear artificial dissipation model and generalized characteristic boundary condition are also used. Aeolion tone noise, cavity noise, and jet noise are investigated. The visualizations of flow-noise are successful and characteristics of noise are studied. It is observed that the propagation directivity of noise is different with that of flow. With the help of CAA method, the visualization of noise is possible.
Real-time Flow Animation Techniques Using Computational Fluid Dynamics
Kang Moon Koo ;
Journal of the Korean Society of Visualization, volume 2, issue 2, 2004, Pages 8~15
With all the recent progresses in computer hardware and software technology, the animation of fluids in real-time is still among the most challenging issues of computer graphics. The fluid animation is carried out in two steps - the physical simulation of fluids immediately followed by the visual rendering. The physical simulation is usually accomplished by numerical methods utilizing the particle dynamics equations as well as the fluid mechanics based on the Navier-Stokes equations. Particle dynamics method is usually fast in calculation, but the resulting fluid motion is conditionally unrealistic. The methods using Navier-Stokes equation, on the contrary, yield lifelike fluid motion when properly conditioned, yet the complexity of calculation restrains this method from being used in real-time applications. This article presents a rapid fluid animation method by using the continuum-based fluid mechanics and the enhanced particle dynamics equations. For real-time rendering, pre-integrated volume rendering technique was employed. The proposed method can create realistic fluid effects that can interact with the viewer in action, to be used in computer games, performances, installation arts, virtual reality and many similar multimedia applications.
CED 분야에서의 가시화 동향
Journal of the Korean Society of Visualization, volume 2, issue 2, 2004, Pages 16~19
On the Visualization of Turbulent Structures Using CFD Technique
Na Yang ;
Journal of the Korean Society of Visualization, volume 2, issue 2, 2004, Pages 20~24
Recent advances in CFD technique along with a rapid growth of computer resources provide valuable opportunities for developing an accurate way of visualizing turbulent structures. Not only this visualization technique made it possible to check the validity of many of theoretical achievements of the past but also it pushes the current turbulence research to a new paradigm. A brief history of visualization study will be summarized and discussed.
Study on the Spin-up of Fluid in a Semi-Circular Container Using a Zonal-Embedded-Grid Method
Suh Yong Kweon ; Yeo Chang Ho ;
Journal of the Korean Society of Visualization, volume 2, issue 2, 2004, Pages 32~37
In this paper the numerical method with a zonal embedded grid system for an incompressible flow within a semi-circular container is presented. The algorithm is validated by its application to some typical flow models including the spin-up flow inside a semi-circular geometry. Flow visualization for the spin-up flows was used by PIV. The results show that at high Reynolds numbers the cyclonic cell at the left-hand side region moves along the circular wall and merges with the cell at the right-hand side region.
Theoretical and Numerical Analysis of Sink Flows under a Background Rotation
Suh Yong Kweon ; Yeo Chang Ho ;
Journal of the Korean Society of Visualization, volume 2, issue 2, 2004, Pages 38~44
Theoretical and numerical studies are given to the sink flows within a rotating circular tank driven by the fluid withdrawal from a bottom circular hole. It was found that, when the upper free surface was set with no-slip boundary conditions, the Ekman boundary-layer develops not only above the bottom surface but under the top surface. The sink fluid is coming from the two Ekman layers, and the mass transfer from the bulk, inviscid region is dependent on the rotational speed. It is also remarkable to see that all the fluid gathered along the axis flows in a form of rapidly rotating fluid column haying almost the same diameter as the bottom hole.
Visualization of Initial Flame Development in an SI Engine
Ohm Inyong ;
Journal of the Korean Society of Visualization, volume 2, issue 2, 2004, Pages 45~51
Initial flame development and propagation were visualized under different fuel injection timings to relate the initial flame development to the engine stability in a port injection SI engine. Experiments were performed in an optical single cylinder engine modified from a production engine and images were captured through the quartz window mounted in the piston by an intensified CCD camera. Stratification state was controlled by varying injection timing. Under each injection condition, the flame images were captured at the pre-set crank angles. These were averaged and processed to characterize the flame. The flame stability was estimated by the weighted average of flame area, luminosity, and standard deviation of flame area. Results show that stratification state according to injection timing did not affect on the direction of flame propagation. The flame development and the initial flame stability are strongly dependent on the stratified conditions and the initial flame stability governs the engine stability and lean misfire limit.
Visualization of Vortex Flow over a Delta Wing with LEX
Shon Myong Hwan ; Chang Jo Won ;
Journal of the Korean Society of Visualization, volume 2, issue 2, 2004, Pages 52~57
The development and interaction of vortices over a delta wing with leading edge extension (LEX) was investigated through off-surface flow visualization using micro water droplets and a laser beam sheet. Angles of attack of
were tested at sideslip angles of
The flow Reynolds number based on the main-wing root chord was
. The wing vortex and the LEX vortex coiled around each other while maintaining comparable strength and identity at a zero sideslip. The increase of angle of attack intensified the coiling and shifted the cores of the wing and LEX vortices inboard and upward. By sideslip, the coiling, the merging and the diffusion of the wing and LEX vortices were increased on the windward side, whereas they were delayed significantly on the leeward side. The present study confirmed that the sideslip angle had a profound effect on the vortex structure and interaction of a delta wing with LEX, which characterized the vortex-induced aerodynamic load.
Visualization Study on a Reduced Frequency of a Dragonfly type wing
Kim Song Hak ; Chang Jo Won ;
Journal of the Korean Society of Visualization, volume 2, issue 2, 2004, Pages 58~65
The purpose of this visualization study is to investigate the effect of reduced frequency qualitatively by examining wake patterns for dragonfly flight motion. Dragonflies have two pairs of wing (a forewing and hindwing) and flight is achieved by a pitching and plunging, so it makes a separation over the wings. The separation affects the wake pattern and changed wake pattern has an influence on lift, drag, and propulsion. This experiment was conducted by using a smoke wire technique and a camera fixed above the test section used to take a photograph of the wake. An electronic device is mounted below the test section to find the exact mean positional angle of the wing. The reduced frequency in the experiment is 0.15, 0.3 and 0.45. Results show that reduced frequency is closely related to the wake pattern that determines flight efficiency.
Two-Phase Flow Patterns of
in a Heated Narrow Rectangular Channel
Kim Yongchan ; Yun Rin ; Chung Jin Taek ;
Journal of the Korean Society of Visualization, volume 2, issue 2, 2004, Pages 66~72
The heat transfer and pressure drop characteristics of
are substantially different from those for CFC and HCFC refrigerants. In addition, geometric effects on two-phase flow patterns of
are also very significant in many respects. Therefore, two-phase flow patterns of
in a narrow rectangular channel or a small diameter tube whose gap size or hydraulic diameter is less than 2 mm are very important to understand heat transfer characteristics and to develop an appropriate heat transfer correlation. In the present study, the evaporation process of
in a narrow rectangular channel is visualized at various test conditions, and then the effects of operating conditions are analyzed.