• Proceedings of the KSME Conference
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• 2000.11b
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• pp.562-567
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• 2000

The Impingement of a weak shock wave discharged from the open end of a shock tube upon a flat plate was investigated using shock tube experiments and numerical simulations. Harten-Yee Total Variation Diminishing method was used to solve axisymmetric, unsteady, compressible flow governing equations. Experiments were carried out to validate the present computations. The effects of the flat plate and baffle plate sizes on the impinging flow field over the flat plate were investigated. Shock Mach number was vaned in the range from 1.05 to 1.20. The distance between the plate and shock tube was changed to investigate the effect on the peak pressure. From both the results of experiments and computations we obtained a good empirical equation to predict the peak pressure on the flat plate.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.27 no.4
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• pp.232-244
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• 2023

The unsteady dynamics of the starting flow of a flat plate is studied by using a vortex shedding model. The model describes the body and separated vortex from the trailing edge of the plate by vortex sheets, retaining a singularity at the leading edge. The model is applied to simulate the flow of an accelerated plate for small angles of attack. For numerical computations, we take two representative cases of the translational velocity of a plate: impulsive translation and uniform acceleration. The model successfully demonstrates the formation of wakes shed from the plate. The wake behind the plate is stronger for a larger angle of attack. Predictions for the lifting force from the model are in agreement with results of Navier-Stokes simulations.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.2
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• pp.195-202
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• 2004

This paper presents the fabrication and evaluation of mechanical behavior for a peristaltic micropump by flow simulation. The valve-less micropump using the diffuser/nozzle is consists of the lower plate, the middle plate, the upper plate and the tube that connects inlet and outlet of the pump. The lower plate includes the channel and the chamber, and the plain middle plate are made of glass and actuated by the piezoelectric translator. Channels and a chamber on the lower plate are fabricated on high processability silicon wafer by the DRIE(Deep Reactive Ion Etching) process. The upper plate does the roll of a pump cover and has inlet/outlet/electric holes. Three plates are laminated by the aligner and bonded by the anodic bonding process. Flow simulation is performed using error-reduced finite volume method (FVM). As results of the flow simulation and experiments, the single chamber pump has severe flow problems, such as a backflow and large fluctuation of a flow rate. It is proved that the double-chamber micropump proposed in this paper can reduce the drawback of the single-chamber one.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.1
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• pp.34-40
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• 2022

In this paper, a flow analysis of a swash-plate type hydraulic piston pump installed on a hydraulic flow supply system for marine vessels is presented. A model and governing equations for computational fluid dynamics (CFD) analyses of swash-plate type hydraulic piston pumps were built, and simulation results regarding the internal flow field of the pump were obtained. By analyzing the internal flow of the swash-plate type hydraulic piston pump, we can confirm the time-dependent stroke of each piston as the pump rotates. We also verified that by analyzing the pulsating flow against the slope of the swash plate, the simulation results match well with the experimental results. The natural frequency of the system was computed to be approximately 380 Hz by applying and analyzing the fast Fourier transform (FFT) of each swash plate slope evaluated.

• Journal of the Korean Solar Energy Society
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• v.27 no.3
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• pp.143-148
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• 2007

It is essential to know the flow characteristics at the risers of Flat-plate solar collector for optimum design. For flat-plate solar collector, it is difficult to experimentally study the effect for the number of riser in the collector for the economic problem. So, this study was performed to show the flow characteristics of flat-plate solar collector with the number of riser using commercial code FLUENT 6.0. The base collector size is chosen with $2\;m^2$ as 1m by 2m in this study, the mass flow rate was estimated 0.04 kg/s using the mass flow rate of 0.02 kg/s per collector area for the certificate test. The number of riser is selected 4, 6, 8, 10, 12, and 14. Through the simulation, the conditions with the risers of 10 or 12 is shown as the optimum design conditions for conventional flat-plate solar collector considering lower pressure drop and more uniformly distributed mass flow rate for higher heat transfer rate without considering heat transfer.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.435-447
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• 2019

Energy Flow Finite Element Analysis (EFFEA) is a promising tool for predicting dynamic energetics of complicated structures at high frequencies. In this paper, the Energy Flow Finite Element (EFFE) formulation of complicated Mindlin plates was newly developed to improve the accuracy of prediction of the dynamic characteristics in the high frequency. Wave transmission analysis was performed for all waves in complicated Mindlin plates. Advanced Energy Flow Analysis System (AEFAS), an exclusive EFFEA software, was implemented using $MATLAB^{(R)}$. To verify the general power transfer relationship derived, wave transmission analysis of coupled semi-infinite Mindlin plates was performed. For numerical verification of EFFE formulation derived and EFFEA software developed, numerical analyses were performed for various cases where coupled Mindlin plates were excited by a harmonic point force. Energy flow finite element solutions for coupled Mindlin plates were compared with the energy flow solutions in the various conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.91-100
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• 2004

Plate heat exchangers (PHE) have been widely used in different industrial applications, because of high heat transfer efficiency per unit volume. Basic study is performed for PHE to the application of intercooler in automobile. In order to understand the flow phenomena in the plate heat exchanger, a channel which was formed by the upper and lower plate in single plate was considered as calculation domains. Because chevrons attached on the upper plate are brazed with chevrons attached on the lower plate, the flow channel has very complex configuration. This complex geometry was analyzed by Fluent. In order to validate this methodology the proper experimental and theoretical data are collected and compared with numerical results. Finally, due to the lack of experimental values for PHE to the application of intercooler, various chevron angles and air velocities at inlet were tested in terms of physical phenomena. From this point of view, results of velocity vector, path lines, static pressure, heat flux, heat transfer coefficient, and Nusselt number are physically reasonable and accepted for the solutions. From these results, the correlations for pressure drop and Nusselt number with respect to chevron angle and Reynolds number in specific PHE are obtained for the design purpose. Thus, the methodology of the flow analysis in the full geometry of the channel was established for the predictions of performance in plate heat exchanger.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.438-443
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• 2001

Plate impingement of the impulse wave discharged from the open end of a duct is numerically investigated using a CFD method. Harten-Yee Total Variation Diminishing method is used to solve the unsteady, compressible flow governing equations. The Mach number, the flat plate inclination and the distance between the duct exit and inclined flat plate are changed to investigate their effects on the impinging flow field. The impulse wave impingement on the inclined flat plate depends on Mach number $M_s$ and the plate inclination $\psi$. The pressure distributions on the inclined flat plate show that for a small r/D, the peak pressure at the center of an inclined flat plate decreases with an increase in the plate inclination $\psi$ in the range of $\psi$ from $45^{\circ}$ to $60^{\circ}$ but for a large r/D, the peak pressure decreases with an increase in $\psi$ in the range of $\psi$ from $75^{\circ}$ to $90^{\circ}$. It is also found that for all of r/D, the peak pressure at the center of an inclined flat plate has a maximum value in $\psi=90^{\circ}$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1141-1142
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• 2013

• Steel and Composite Structures
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• v.22 no.6
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• pp.1261-1280
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• 2016

We study chaotic motion in a nonlinear laminated composite plate under subsonic fluid flow and a simultaneous external load in this paper. We derive equations of motion of the plate using the von-$K{\acute{a}}rm{\acute{a}}n^{\prime}s$ hypothesis and the Hamilton's principle. Galerkin's approach is adopted as the solution method. We then conduct a divergence analysis to obtain critical velocities of the transient flow. Melnikov's integral approach is used to find the critical parameters in which chaos takes place. Effects of different parameters including the aspect ratio, plate material and the ply angle in laminates on the critical flow speed are investigated. In a parametric study, we show that how the linear and nonlinear stiffness of the plate and the load frequency and amplitude would influence the chaotic behavior of the plate.