• Journal of Korean Society of Water and Wastewater
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• v.25 no.1
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• pp.31-39
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• 2011

In order to suggest the methodology for achieving anti-vortex device within multi pump intake well, CFD(Computational Fluid Dynamics) simulation were conducted for two alternative suggestions. Multi-intake sump model with anti-vortex device basins were designed and the characteristics of submerged vortex were investigated in the flow field by numerical simulation. From the results of simulations, to install the horizontal plate and vertical cross plates within basins were effective for preventing air-induction vortex.

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.10-10
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• 2006

• 한국초전도학회:학술대회논문집
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• v.13
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• pp.20-20
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• 2003

• Wind and Structures
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• v.16 no.5
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• pp.411-431
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• 2013

A computational study of vortex-induced transverse vibrations of a cylinder with low mass-damping is presented. An Arbitrary Lagrangian-Eulerian (ALE) formulation of the Unsteady Reynolds-Averaged Navier-Stokes equations (URANS), along with the Spalart-Allmaras (SA) one-equation turbulence model, are coupled conservatively with rigid body motion equations of the cylinder mounted on elastic supports in order to study the amplitude and frequency response of a freely vibrating cylinder, its flow-induced motion, Vortex Street, near-wake flow structure, and unsteady loading in a moderate range of Reynolds numbers. The time accurate response of the cylinder from rest to its limit cycle is studied to explore the effects of Reynolds number on the start of large displacements, motion amplitude, and frequency. The computational results are compared with published physical experiments and numerical studies. The maximum amplitudes of displacements computed for various Reynolds numbers are smaller than the experimental values; however, the overall agreement of the results is quite satisfactory, and the upper branch of the limit-cycle displacement amplitude vs. reduced velocity response is captured, a feature that was missed by other studies. Vortex shedding modes, lock-in phenomena, frequency response, and phase angles are also in agreement with experiments.

• Journal of the Korean Magnetics Society
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• v.18 no.4
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• pp.127-130
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• 2008

We report a theoretical description of ferromagnetic vortex motion in sub-micrometer size magnetic thin film. Based on Thiele's equation combined with later theoretical achievements, we derive the analytic description of dynamics of ferromagnetic vortex core as a damped harmonic oscillatory motion. Consequently, the relations about frequency and damping constant in damped harmonic oscillation are presented. The validity of the results is verified through micromagnetic simulation.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.449-453
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• 2007

After over a century of effort by researchers and engineers, the problem of bluff body flow, in particular vortex shedding frequency, remains almost entirely in the empirical, descriptive realm of knowledge. Computational methods have been systematically applied for vortex-induced vibrations of the cable-stayed bridge with steel composite deck by unsteady wind loadings due to vortex-shedding. The focus of this paper is to predict the vortex-induced vibration of the cable-stayed bridge with steel composite deck based computational fluid dynamics(CFD).

• Wind and Structures
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• v.32 no.1
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• pp.1-9
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• 2021

Vortex generators are commonly used in mechanical engineering and the aerospace industry to suppress flow separation owing to their advantages of simple structure, economic viability, and high level of efficiency. Owing to the flow separation of the incoming wind on the leading edge, a suction area is formed on the roof surface, which results in a lifting effect on the roof. In this research, vortex generators were installed on the windward surface of a flat roof and used to disturb to roof flow field and reduced suction based on flow control theory. Computational fluid dynamics (CFD) simulations were performed in this study to investigate the effects of vortex generators on reduce suction. It was determined that when the vortex generator was installed on the top of the roof on the windward surface, it had a significant control effect on reduce suction on the roof leading edge. In addition, the influence of parameters such as size, placement interval, and placement position of the vortex generator on the control effect of the roof's suction is also discussed.

• Journal of Ocean Engineering and Technology
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• v.34 no.2
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• pp.89-96
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• 2020

In this study, the Norbury-Fraenkel family of vortex rings is analyzed using a contour dynamics method for the stream function, which significantly reduces the numerical burden in the calculation. The stream function is formulated as the integral along the contour of the vorticity core. The integration over the logarithmic-singular segment is evaluated analytically, and the positions of the nodal points of the contour are calculated directly. The shapes of the cores and the dividing stream surfaces are found based on the mean core radius. Compared with other studies, the proposed method is verified and found to be more efficient.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.448-453
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• 2017

We conducted the three-dimensional fluid flow analysis in a Taylor reactor using computational fluid dynamics (CFD). The Taylor flow can be categorized into five regions according to Reynolds number, i.e., circular Couette flow (CCF), Taylor vortex flow (TVF), wavy vortex flow (WVF), modulated wavy vortex flow (MWVF), and turbulent Taylor vortex flow (TTVF), and we investigated the flow characteristics at each region. For each region, the shape, number and length of vortices were different and they influenced on the bypass flow. As a result, the Taylor vortex was found at TVF, WVF, MWVF and TTVF regions. The highest number of Taylor vortex was observed at TVF region, while the lowest at TTVF region. The numerical model was validated by comparing with the experimental data and the simulation results were in good agreement with the experimental data.

• Journal of Ship and Ocean Technology
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• v.7 no.3
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• pp.13-33
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• 2003

This paper presents a numerical study on tip vortex cavitation inception predictions based on non-spherical bubble dynamics including splitting and jet noise emission. A brief summary of the numerical method and its validation against a laboratory experiment are presented. The behavior of bubble nuclei is studied in a tip vortex flow field at two Reynolds numbers, provided by a viscous flow solver. The bubble behavior is simulated by an axisymmetric potential flow solver with the effect of surrounding viscous flow taken into account using one way coupling. The effects of bubble nucleus size and Reynolds number are studied. An effort to model the bubble splitting at lower cavitation numbers is also described.