• 한국전산유체공학회:학술대회논문집
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• 1996.05a
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• pp.105-110
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• 1996

In the present paper, flow fields around two dimensional single and two circular cylinders are analysed by a finite difference method. Navier-Stokes and the continuity equations an solved to simulate the flow fields. A overlapped grid system(the composite of a body boundary-fitted grid system near the body and a rectangular grid system for other flow fields) is used for this calculation. In the use of overlapped grid system, it is most significant thing to exchange the physical quantities from one grid system to the other one continuously, In this research, the linear interpolations of physical quantaties are done for this purpose in the overlapped region. The numerical calculations are carried out for the flows around a circular cylinder and two cylinders to verify the accuracy of present method. The flow fields around two cylinders facing the flow with side by side and tandem arrangement are analysed. The results are compared to other experimental and computational ones done in other single grid system.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.2
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• pp.59-68
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• 2010

The aim of this work is to analyze high temperature flows around an axisymmetric blunt body taking into account chemical and vibrational non-equilibrium state for air mixture species. For this purpose, a finite volume methodology is employed to determine the supersonic flow parameters around the axisymmetric blunt body. This allows the capture of a shock wave before a blunt body placed in supersonic free stream. The numerical technique uses the flux vector splitting method of Van Leer. Here, adequate time stepping parameters, along with Courant, Friedrich, Lewis coefficient and mesh size level are selected to ensure numerical convergence, sought with an order of $10^{-8}$.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.183-190
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• 2009

The objective of this study is to get simulation data about pulsatile flow around an interior solid body inside a bifurcated tube. All the processes were based on CFD method, with a commercial FVM code, SC/Tetra ver. 6.0 for solving, and with CATIA R16 for generating geometries. The bifurcated tube models were drawn with the bifurcated angle of 45 degrees, considering Murray's law about the diameter ratio. With various locations of the object, the effects of flow on the drag were considered. For the pulsating flow condition, the velocity wave profile was given as the inlet boundary condition. To validate all the result, the simulation was compared with the existing data of the other papers first. Overall flow field of both data were similar, but there was some difference at a zero velocity. Therefore the next simulation was continued with the sine wave profiles where there is no negative flow, and then the data was compared with one of the pulmonary artery velocity where there is negative flow. The final process was to calculate flow variables such as the wall shear stress (WSS) and to compute the drag of the solid object.

• Proceedings of KOSOMES biannual meeting
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• 2007.05a
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• pp.161-168
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• 2007

In this paper, the floating body with double barriers is introduced with a study on the flow patterns and characteristics in around the floating body by using 2 frame p article tracking method. This paper introduce an analisys method to predict the characteristics of flow around the neighbording fields of Floating Body with double barriers in order to investigate a high performance model. Flow visualization has conducted in a circulating water channel by a high speed camera and etc. Flow phenomena according to velocity distribution and flow separation around the floating body with double barriers were obtained by two-dimensional PIV system.

• Journal of the Korean Society of Visualization
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• v.18 no.2
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• pp.39-45
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• 2020

Problems related with flows around structures are typical in various engineering fields. The characteristics of these flow structures depend strongly on the shape of the body. The flow regime around square cylinders which are also employed in various applications has also been investigated. In addition to a single body, flows past closely spaced structures arranged in tandem are observed in numerous practical applications. In this study, the flow characteristics around the circular and the square cylinder were investigated according to S/D. The velocity fields and Reynolds stress of the single cylinders were acquired to explain the flow behaviors between tandem cylinders. The differences observed in the flow behaviors of square and circular cylinders were studied. The flow patterns around two tandem cylinders can be classified into three types of wake interference behaviors according to S/D. This is related with the flows between cylinders.

• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.99-109
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• 1998

This paper describes the analysis of flow and aeroacoustic field around a car-like body. The governing equations, 3-D unsteady incompressible Navier-Stokes equations, are solved with the iterative time marching scheme. The Chimera grid technique has been applied to efficiently simulate the flow around the side-view mirror, After the flow field analysis has been converged, the aerodynamic noise analysis of the side-view mirror has been performed by solving Ffowcs Williams and Hawkings equation. From the present numerical simulation, the A- and C-pillar vortex are evidently shown and the aerodynamic noise level induced by the side-view mirror is predicted to about 100dB.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.4
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• pp.379-388
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• 2008

A hybrid Cartesian/immersed boundary code is expanded to simulate flow field around a three-dimensional body which undergoes large dynamic deformation. Immersed boundary nodes are automatically distributed based on the edges crossing triangles on body boundary. Velocity vectors are reconstructed at those immersed boundary nodes along local normal lines to the boundary. The reconstruction of pressure is avoided using the hybrid staggered/non-staggered grid method. The developed code is validated through comparisons with other results on laminar flow over a sphere. The code is applied to simulate flow around a foil which is attached to a body of revolution and rotates under periodic deformation. The periodic variation of the tip vortex is observed and the effects of the deformation on hydrodynamic force acting on the body are investigated.

• 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.

• Journal of computational fluids engineering
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• v.12 no.1
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• pp.1-8
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• 2007

A code is developed using the hybrid Cartesian/immersed boundary method and it is applied to simulate flows around a three-dimensional deforming body. A new criterion is suggested to distribute the immersed boundary nodes based on edges crossing a body boundary. Velocities are reconstructed at the immersed boundary nodes using the interpolation along a local normal line to the boundary. Reconstruction of the pressure at the immersed boundary node is avoided using the hybrid staggered/non-staggered grid method. The developed code is validated through comparisons with other experimental and numerical results for the velocity profiles around a circular cylinder under the forced in-line oscillation and the pressure coefficient distribution on a sphere. The code is applied to simulate the flow fields around a plate whose tail is periodically flapping under a translation. The effects of the velocity and acceleration due to the deformation on the periodic shedding of pairs of tip vortices are investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.335-338
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• 2007

In the case of an antiaircraft missile, high angle of attack flight capability is required to get the agile maneuverability in a supersonic flow. Even through a symmetric slender body does not have side slip, asymmetric vortex is generated at high angle of attack conditions. This asymmetric vortex produces unnecessary side force and yawing moment; hence, these effects deteriorate directional stability. In this study, the numerical analysis of asymmetric vortices around the slender body was conducted at high angle of attack supersonic flow. In order to simulate the vortices, a bump is installed on the nose of the slender body. As a result of the numerical analysis, the asymmetric vortices around the slender body could be simulated.