• Journal of Ocean Engineering and Technology
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• v.33 no.3
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• pp.245-251
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• 2019

When an offshore foundation is exposed to waves and currents, local scour could develop around a pile and even lead to structural failure. Therefore, understanding and predicting the scour due to sediment transport around foundations are important in the engineering design. In this study, the flow and scour around a monopole foundation exposed to a current were investigated using a method that coupled the computational fluid dynamics (CFD) and discrete element method (DEM). The open source computation fluid dynamics library OpenFOAM and a sediment transport library were coupled in the OpenFOAM platform. The incipient motion of the particle was validated. The flow fields and sediment transport around the monopole were simulated. The scour depth development was simulated and compared with existing experimental data. For the upstream scour hole, the equilibrium scour depth could be reproduced qualitatively, and it was underestimated by about 23%.

• Journal of Mechanical Science and Technology
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• v.15 no.5
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• pp.613-622
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• 2001

Interaction of blood flow and leaflet behavior in a bileaflet mechanical heart valve was investigated using computational analysis. Blood flows of a Newtonian fluid and a non-Newtonian fluid with Carreau model were modeled as pulsatile, laminar, and incompressible. A finite volume computational fluid dynamics code and a finite element structure dynamics code were used concurrently to solve the flow and structure equations, respectively, where the two equations were strongly coupled. Physiologic ventricular and aortic pressure waveforms were used as flow boundary conditions. Flow fields, leaflet behaviors, and shear stresses with time were obtained for Newtonian and non-Newtonian fluid cases. At the fully opened phase three jets through the leaflets were found and large vortices were present in the sinus area. At the very final stage of the closing phase, the angular velocity of the leaflet was enormously large. Large shear stress was found on leaflet tips and in the orifice region between two leaflets at the final stage of closing phase. This method using fluid-structure interaction turned out to be a useful tool to analyze the different designs of existing and future bileaflet valves.

• Journal of Welding and Joining
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• v.15 no.3
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• pp.36-46
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• 1997

Dynamics of molten drop detachment in the Gas Metal Arc (GMA) welding is investigated using the Volume of Fluid(VOF) method. The electromagnetic effects are included in the formulation of the VOF method which has been widely used to analyze the dynamics of the fluid having a free surface. The molten drop geometry, pressure and velocity profiles within the drop are calculated numerically in the cases of globular and spray transfer modes. It appears that the velocity and current distribution affect metal detachment. It is found that the taper is formed and maintained during the spray transfer by the electromagnetic force. Predicted results show reasonably good agreement with the available experimental data which validates the application of the VOF method to metal transfer analysis.

• International Journal of Vascular Biomedical Engineering
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• v.2 no.1
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• pp.1-10
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• 2004

Circulatory disease is the number two cause of death next to cancer in Korea, while the cardiovascular disease alone is the number one cause of death in the US. In the present article, some background, current status and future prospects of biomedical engineering esearch on circulatory disorders are discussed in terms of the origin of atherosclerosis, computational fluid dynamics and medical imaging techniques, clinical treatments and fluid dynamics, advances in stents, hemodynamic analysis of artificial heart, and artificial blood. In particular, the importance of close collaboration of medicine and fluids engineering is emphasized.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.735-738
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• 2011

This paper proposed the method to find out the optimal sensing point of temperature in test-bed with the sensor of temperature, such as real residence. We selected optimal locations by checking temperature change which was simulated by the means of CFD (Computational Fluid Dynamics) and the variation of air flow. We installed 30 temperature sensors in real place. After that, we compared the real one with the result of simulation.

• Wind and Structures
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• v.20 no.4
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• pp.565-578
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• 2015

A wind energy assessment is an integrated analysis of the potential of wind energy resources of a particular area. In this work, the wind energy potentials for Mauritius have been assessed using a Computational Fluid Dynamics (CFD) model. The approach employed in this work aims to enhance the assessment of wind energy potentials for the siting of large-scale wind farms in the island. Validation of the model is done by comparing simulated wind speed data to experimental ones measured at specific locations over the island. The local wind velocity resulting from the CFD simulations are used to compute the weighted-sum power density including annual directional inflow variations determined by wind roses. The model is used to generate contour maps of velocity and power, for Mauritius at a resolution of 500 m.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.64-71
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• 2011

In this study, steady and unsteady aerodynamic analyses of a huge rocket configuration have been conducted in a transonic flow region. The launch vehicle structural response are coupled with the transonic flow state transitions at the nose of the payload fairing. The developed fluid-structure coupled analysis system is applied for aeroelastic computations combining computational structural dynamics(CSD), finite element method(FEM) and computational fluid dynamics(CFD) in the time domain. It can give very accurate and useful engineering data on the structural dynamic design of advanced flight vehicles. For the nonlinear unsteady aerodynamics in high transonic flow region, Navier-Stokes equations using the structured grid system have been applied to the rocket configurations. Also, it is typically shown that the current computation approach can yield realistic and practical results for rocket design and test engineers.

• Nuclear Engineering and Technology
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• v.47 no.3
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• pp.284-292
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• 2015

A numerical calculation with the commercial computational fluid dynamics code CFX-14.0 was conducted for a test facility simulating the Canadian deuterium uranium moderator thermal-hydraulic. Two kinds of moderator thermal-hydraulic tests at Stern Laboratories Inc. were performed in the full geometric configuration of the Canadian deuterium uranium moderator circulating vessel, which is called a calandria tank, housing a matrix of horizontal rod bundles simulating calandria tubes. The first of these tests is the pressure drop measurement of a cross flow in the horizontal rod bundles. The other is the local temperature measurement on the cross section of the horizontal cylinder vessel simulating the calandria system. In the present study, the full geometric details of the calandria tank are incorporated in the grid generation of the computational domain to which the boundary conditions for each experiment are applied. The numerical solutions are reviewed and compared with the available test data.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.8 s.251
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• pp.818-824
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• 2006

The hydrodynamic performance analysis of an axial-flow main coolant pump for the modular nuclear reactor has been carried out using a commercial computational fluid dynamics (CFD) software. The prediction capability of the CFD software adopted in the present study was validated in comparison with the experimental data. Predicted performance curves agree satisfactorily well with the experimental results for the main coolant pump over the normal operating range. π Ie prediction method presented herein can be used effectively as a tool for the hydrodynamic design optimization and assist the understanding of the operational characteristics of general purpose axial-flow pumps.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.5
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• pp.53-60
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• 2022

In this study, the conceptual design and performance evaluation of a personal air vehicle (PAV) is presented, which is a potential futuristic individual transportation. The blade element theory (BET) is employed to compute a rotational velocity. A computational fluid dynamics (CFD) simulation is performed to investigate the difference in the thrust performance in the rotor axis distance of a quad-copter PAV in hovering. Modal analysis is performed to create a Campbell diagram to investigate critical speed. Consequently, a quad-copter PAV changes the aerodynamics thrust and critical velocity according to the rotor axis distance.