• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.420-425
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• 2006

Measurements results of flow-structure-interactions (FSI) of an air-lifted body are introduced. An adaptive stereoscopic-PIV system has been constructed for the measurements of the air-lifted body. The measurement system consists of two cameras and optical sensors. The flow characteristics around a lifted cylinder body(length=60mmm, diameter =10mm, polystyrene) in the swirling flow field in a vertical pipe (length=600mm, inner diameter=) are investigated by the use of the constructed adaptive stereoscopic-PIV system. The images of the two cameras were used for the analysis of the flow fields around the floated cylinder body. The images of the cylinder body captured by the two cameras were used for the analyses of its motions. Four optical sensors (LED) were used for the detection of the postures of the freely-lifted cylinder body. The FSI analyses have been carried out to find the physical conditions at which the floating body is stabilized with its upright postures.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.53-54
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• 2006

Experimental analyses on the Hydroelastic Flow-Structure Interactions on pulsed impinged jet is measured with the FSIMS(Flow-Structure Interaction Measurement System. The nozzle diameter is D=15mm and two major experiments have been carried out for the cases of the distance between the nozzle tip to the elastic wall is 6.0. The pulsed jets were controlled by a solenoid valve and were impinged onto an elastic plate (material: silicon, diameter: 350mm, thickness: 0.5mm, hardness: 15). The Reynolds numbers were 20,000 and 24,000 when the jets were impinged with the volume velocities. The results showed that the elastic plate moved slightly to the opposite direction of the jet direction at the time of valve opening. It has been shown that the vortices travelling over the surface of the wall made the elastic wall distorted locally due to a vector forces between rotating forces of the vortex and a newly-incoming flow.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.81-89
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• 2009

Performance tests on the 3-Dimensional Flow-Structure-Interactions-Measurement System(FSIMS) have been carried out. Experimental data obtained by the FSIMS on a floating cylinder have been used to generate a set of artificial images. Comparisons between the data obtained by the use of the artificial images and those original experimental data have been made. Another set of artificial images have also been generated based on theoretically modulated sinusoidal motions, and comparisons between the data obtained by the use of these artificial images and the theoretical ones have been carried out. It has been verified that the FSIMS has a measurement uncertainty of 0.04-0.06mm/frame for velocity vectors and 0.002-0.01mm for the cylinder's positions.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1574-1579
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• 2004

A simultaneous measurement system that can analyze the flow-structure interactions(FSI) has been constructed and analyses on the flow field and the motion field of a floating cylinder was made. The three-dimensional vector fields around the cylinder are measured by 3D-PTV technique while the motion of the cylinder forced by the flow field is measured simultaneously with a newly developed motion tracking algorithm(bidirectional tracking algorithm). The cylinder is pendant in the working fluid of a water channel and the surface of the working fluid is forced sinusoidal to make the cylinder bounced. The interaction between the flow fields and the cylinder motion is examined quantitatively.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.274-278
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• 2004

A simultaneous measurement system that can analyze the flaw-structure interactions has been developed This system consists of four CCD cameras, two for capturing instantaneous flaw fields and two for tracking a solid body. The three-dimensional vector fields around a cylinder are measured while the motion of the cylinder forced by the flow field is measured simultaneously with the constructed system The cylinder is pended in the working fluid of a water channel and the surface of the working fluid is forced sinusoidal to make the cylinder bounced Reynolds number for the mean main stream is about l000. The interaction between the flaw fields and the cylinder motion is examined quantitatively.

• Wind and Structures
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• v.3 no.4
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• pp.291-302
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• 2000

A new finite element technique to solve the problem of wind and structure interactions is presented. Conventionally, wind analysis is performed on the Eulerian description in which the finite element mesh would not move in accordance with the wind flow. However, it is not the case in wind-structure interaction problems because nodes attached to the surface of structure should move with the displacement of structure. The arbitrary Lagrangian-Eulerian (ALE) method treats the mesh and flow independently, and allow the mesh to move. In this study, the analysis domain is divided into regions of the structure, air around the structure and the interface of two regions. To satisfy the compatibility and equilibrium conditions between separated regions and to carry out the efficient analysis, the rigid link is used. Also the equation of wind and that of structure are arranged in a single matrix equation.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.159-160
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• 2002

New S-shaped aeroelastic mesoflaps are utilized to control normal shock/boundary-layer interactions. New generation of the mesoflaps is designed f3r a better rigidness and a good flow uniformity across the ulteractions. ,Major advantages of the mesoflap system can be a better total pressure recovery downstream of the interactions due to the lambda shock structure over the flap system, and a rehabilitation of the thickened boundary layer due to bleeding through a cavity underneath the flap system. Skin friction has been measured downstream of the interactions, using the laser interferometer skin friction (LISF) meter, which optically detects the rate of thinning of an oil film applied to the test surface. Various flap-thicknesses of the S-shaped mesoflap arrays are tested, and the results are compared to the solid-wall reference case. Overall, not much difference in the level of skin friction is noticed for the S-shaped flap arrays of various thicknesses, and its level is lower than the skin friction downstream of the solid-wall interaction

• Wind and Structures
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• v.32 no.4
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• pp.309-319
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• 2021

The vortex-drift pattern over a girder surface, actually demonstrating the complex fluid-structure interactions between the structure and surrounding flow, is strongly correlated with the VIVs but has still not been elucidated and may be useful for modeling VIVs. The complex fluid-structure interactions between the structure and surrounding flow are considerably simplified in constructing a vortex model to describe the vortex-drift pattern characterized by the ratio of the vortex-drift velocity to the oncoming flow velocity, considering the aerodynamic work. A spring-suspended sectional model (SSSM) is used to measure the pressure in wind tunnel tests, and the aerodynamic parameters for a typical streamlined closed-box girder are obtained from the spatial distribution of the phase lags between the distributed aerodynamic forces at each pressure point and the vortex-excited forces (VEFs). The results show that the ratio of the vortex-drift velocity to the oncoming flow velocity is inversely proportional to the vibration amplitude in the lock-in region and therefore attributed to the "lock-in" phenomena of the VIVs. Installing spoilers on handrails can destroy the regular vortex-drift pattern along the girder surface and thus suppress vertical VIVs.

• Computational Structural Engineering
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• v.29 no.1
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• pp.24-34
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• 2016

• Korea-Australia Rheology Journal
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• v.21 no.1
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• pp.39-46
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• 2009

Atherosclerosis is a disease that narrows, thickens, hardens, and restructures a blood vessel due to substantial plaque deposit. The geometric models of the considered stenotic blood flow are three different types of constriction of cross-sectional area of blood vessel; 25%, 50%, and 75% of constriction. The computational model with the fluid-structure interaction is introduced to investigate the wall shear stresses, blood flow field and recirculation zone in the stenotic vessels. The velocity profile in a compliant stenotic artery with various constrictions is subjected to prescribed physiologic waveform. The computational simulations were performed, in which the physiological flow through a compliant axisymmetric stenotic blood vessel was solved using commercial software ADINA 8.4 developed by finite element method. We demonstrated comparisons of the wall shear stress with or without the fluid-structure interaction and their velocity profiles under the physiological flow condition in the compliant stenotic artery. The present results enhance our understanding of the hemodynamic characteristics in a compliant stenotic artery.