• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.7
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• pp.692-700
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• 2012

Vibration intensity has been used to localize vibration source of a vibrating system. Not only that, vibration intensity has also been used for structural diagnostic in identifying crack and mounted stiffeners. To clearly identify the location of vibration source and understand the changes of energy transmission path, clear flow visualization is required. Most of previous works used vectors to indicate the magnitude and direction of emerging vibration energy and transmission paths. However, due to the large surface area of a plate like-structure, clear transmission paths cannot be achieved using vector visualization. This becomes an issue when detail vector flow at all locations of the whole plate surface is required. In this study, streamlines visualization is used to clearly indicate the power flow transmission path at all plate surface. By using streamlines representation, not only clear transmission paths are obtained, but also improves the vector visualization which helps us to understand the changes of the energy flow especially for stiffened plates. In this study, vibration intensity computation is firstly compared to previous work to validate the vibration intensity computation. To clearly show the power flow transmission paths, streamlines representation is shown. This representation overcomes the unclear vector direction especially for stiffened plates. Different pattern of energy transmission path can be observed using streamlines representation for stiffened and unstiffened plate. The complex streamlines pattern can also be observed at high resonance frequencies which is unclear by using vector representation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.8
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• pp.777-783
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• 2012

Vibration intensity has been used to identify the location of a vibration source in a vibrating system. By using vectors representation, the source of the power flow and the vibration energy transmission paths can be revealed. However, due to the large surface area of a plate-like structure, clear transmission paths cannot be achieved using the vectors representation. Experimentally, for a large surface object, the number of measured points will also be increased. This requires a lot of time for measurement. In this study, streamlines representation is used to clearly indicate the power flow transmission paths at all surface plate for FEM and experiment. To clearly improve the vibration intensity transmission paths, streamlines representation from experimental works and FEM computations are compared. Improved transmission paths visualization for both FEM and experiment are shown in comparison to conventional vectors representation. These streamlines visualization is useful to clearly identify vibration source and detail energy transmission paths especially for large surface plate-like structures. Not only that, this visualization does not need many measured point either for experiment or FEM analysis.

• The Journal of the Korea Contents Association
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• v.18 no.6
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• pp.27-37
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• 2018

Streamline generation is one of the most representative visualization methods to analyze the flow stream of fluid dynamics dataset. It is a challenging problem, however, to determine the seed locations for effective streamline visualization. Meanwhile, it needs much time to compute effective seed locations and streamlines on the massive flow dataset. In this paper, we propose not only an importance based method to determine seed locations for the effective streamline placements but also a parallel streamline visualization method on the distributed visualization system. Moreover, we introduce case studies on the real fluid dynamics dataset using GLOVE visualization system to evaluate the proposed method.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1794-1800
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• 2001

Mass conservation is a key issue for accurate streamline and stream surface visualization of flow fields. This paper complements an existing method (Feng et al. 1997) for CFD velocity fields defined at discrete locations in space that uses dual stream functions to generate streamlines and stream surfaces. Conditions for using the method have been examined and its limitations defined. A complete set of dual stream functions for all possible cases of the linear fields on which the method relies are presented. The results in this paper are important for developing new methods for mass conservative streamline visualization from CFD and using the existing method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.3
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• pp.218-226
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• 1994

Laminar flow and heat transfer in a channel with blockages are obtained numerically in a Reynolds-number range of $100{\leq}Re{\leq}400$. A boundary-fitted curvilinear coordinate system is generated for irregular boundary of the physical region, and solutions of Navier-Stokes equation and energy equation are obtained by finite analytic method in the transformed computational domain. The flow separates in downstream of the blockage and the length of separated-flow region increases with Reynolds number. The heat flux is high on the top of the blockages and increase in the heat transfer occurs where the fluid reattaches the wall. Comparison between computed streamlines and experimental flow-visualization is also presented and discussed.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.59-62
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• 2003

The near wake behind a sinusoidal cylinder at Re=5200 has been investigated using DPIV system. The velocity fields, streamlines and vorticity contours of the mean flow were compared at the nodal, saddle and middle planes with those of a right circular cylinder. For the sinusoidal cylinder, the vortex core moves downstream and the vortex formation region is expanded in streamwise direction while suppressed in transverse direction at the nodal plane. At the saddle and the middle plane the vortex spread in both streamwise and transverse directions, forming the maximum vortex region at the saddle plane.

• Journal of the Korean Society of Visualization
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• v.4 no.1
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• pp.41-46
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• 2006

In this study, one-way fluid structure interaction analysis(FSI) on wind turbine blade was performed. Both a quantitative fluid analysis on 3-bladed wind turbine and a structural analysis using the surface pressure data resulting from fluid analysis were carried out. Streamlines and angle of attack was easily acquired from analysis results, we showed the inlet velocity that the stall begins to occur. In the structural analysis, structural displacement and maximum stress of the two comparative models was calculated. The location that has maximum stress was found. The pressure difference between back and front part of the blade increases as the inlet velocity increase. The torque and maximum with regard to inlet velocity was also presented.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.48-51
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• 2004

Chemical Mechanical Polishing(CMP) is popularly used in production of semiconductor because of large area polishing ability probability of improvement for more integrated circuit. However, present CMP processing causes some non-uniformity errors which can be critical for highly integrated circuit. Previous studies predict that flow-field of slurry during CMP can create non-uniformity, but no quantitative measurement has conducted. In this study, using PIV, slurry velocity flow-field during CMP is measured by changing the ratio of RPM of pad and carrier with tuned PIV system adequate for small room in CMP machine and Cabot's non-groove pad Epad-A100. The result show that velocity of slurry is majorly determined by pad-rpm and the ratio of between carrier and pad rpm make some changes in streamlines.

• Journal of the Korean Society of Visualization
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• v.7 no.2
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• pp.56-63
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• 2010

In this work, a dielectrophoresis-based particle-separation device is developed which is to be used to continuously separate particles in microchannels. We fabricated the particle-separation device with combining the benefits of electrode-based DEP and insulator-based DEP. The DEP forces are generated by an array of electrodes located in both sidewalls of a main channel. According to the magnitude and frequency of electrical signals, particles with different dielectric properties experience different DEP forces, and therefore, continuously move along different streamlines in the main flow channel without need of pre-focusing process. Based on this mechanism, we examined the performance of the device by controlling the trajectory of polystyrene particles. This device is applicable to the investigation of dielectric properties of biological cells as well as the continuous separation of biological cells.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.784-795
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• 1995

This paper represents the results of the experiments of the three-dimensional flow and the aerodynamic loss caused by the three-dimensional flow within the plane bucket blades. To research the secondary flow and the aerodynamic loss, the large-scale plane bucket blade of lst-stage in the low pressure steam turbine is made of FRP. The detailed investigation of the secondary flow and the aerodynamic loss using 5-hole pressure probe within turbine cascade has been carried out in the low speed wind tunnel. The limiting streamlines of the suction and endwall surface have been visualized by the oil film method. The flow visualization of the secondary flow has been performed by the laser light sheet technique and image processing system. By using the method mentioned above, it is possible to observe the evolution of the pitchwise mass-averaged flow deviation angle and total pressure loss coefficient, the secondary flow, and the aerodynamic loss through the cascade.