• Journal of the Korean Society of Visualization
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• v.17 no.2
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• pp.73-82
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• 2019

The subsurface vortex - which occurs inside the cylindrical sump - was visualized through Computational Fluid Dynamics (CFD) and experiment. The analysis of subsurface vortex inside the cylindrical sump was already carried out using CFD techniques by the first author. To understand the subsurface vortex more clearly, an experimental analysis was carried out with a 1/5th scale model; and the flow rate was calculated according to the similarity law. The experimental results of vortex visualization matches well with the CFD results. The surface roughness model and Anti Vortex Device (AVD) model have been investigated to control the subsurface vortex. For the case of average surface roughness of 1mm and 5mm, the subsurface vortex appears and the vorticity is higher when compared to that of a smooth surface condition. However, for the AVD model, the subsurface vortex is completely removed and the internal flow is stabilized.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.593-597
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• 2005

In order to study the characteristics of the subsurface vortex the flow fields of the three pump sump models were analysed by the numerical simulation. The calculation results show that there are circulation flows in the pump sump model and maximum vorticity strength which make iso-surface from the wall to the pump inlet could be used for predicting the subsurface vortex generation. Also, the flow field for the sump model with anti-vortex devices simulated and the results shows that there is no vorticity value which make iso-surface from the sump wall to the pump inlet.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.592-595
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• 2011

A numerical investigation on a suction vortices, free vortices and subsurface vortices behavior in the model sump system with multi-intakes is performed A test model sump and piping system were designed based on Froude similitude for the prototype of the recommended structure layout by HI-9.B Standard for Pump Intake Design of the Hydraulic Institute. A numerical analysis of three dimensional multiphase flows through the model sump is performed by using the finite volume method of the CFX code with multi-block structured grid systems. A ${\kappa}-{\omega]$ ShearStressTransportturbulencemodelandthe Rayleigh-Plesset cavitation model are used for solving turbulence cavitating flow. From the numerical analysis, several types of vortices are reproduced and their formation, growing shedding and detailed vortex structures are investigated. To reduce abnormal vortices, an anti-vortex device is considered and its effect is investigated and discussed.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.2
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• pp.76-85
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• 1993

In order to predict the free surface signature of turbulent ship wakes two things are essential; a basic understanding of the mechanism of turbulent vortical flow/free surface interactions and a mathematical model to accurately predict the signature. The goal of the study described here is both to supplement experimental work to obtain basic understanding, as well as to condense this understanding in a model(or models) that captures the essential phenomena and thus allows predictions. To do so we followed two main paths guided by experimental observations. One is full simulations of the flow using the clavier-Stokes equations. The other is a vortex modeling, where the vortical structures of the flows are approximated by idealized structures, an the interaction assumed to be essentially inviscid. These approaches complement each other. Full simulations are only applicable to small scale phenomena, where the system is simple, and the Reynolds number is low. The vortex modeling, on the other hand, cannot represent essentially viscous aspects of the problem such as the effect of contamination gradient. Obviously, the modeling is what may eventually lead to a prediction method; the full simulations-too limited to mimic all but the simplest circumstances-are to aid and support the construction of realistic models. We address two-dimensional aspects of the vortex/free surface interaction first. Secondly we obtain some basic understanding of the interaction process through an experiment and then talk about several three-dimensional problems hoping to develop a successful prediction model.