• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.207-212
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• 2001

In this study, spin-up flows in a shallow rectangular container are analysed by using three-dimensional computation. We compared our results with those obtained by quasi three-dimensional computation. Our results show that quasi S-D solustion is not accurate enough and it provides far less damped solution.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.7
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• pp.1005-1013
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• 2002

Spin-up is a transient flow phenomenon occurring in a container when it starts to rotate from rest or its rotational speed increases from a low to high value. However, most studies on this subject have been for two-dimensional approximation. In this study, spin-up flows in a shallow rectangular container are analysed by using three-dimensional computation. We compared our results with those obtained by others using basically two-dimensional computation. Effect of two parameters, Reynolds number and liquid depth on the flow evolution is studied. We found that 2-D result is not accurate enough, and the vertical velocity distribution should be assumed of a fourth-order polynomial function for a better comparison.

• Journal of Ocean Engineering and Technology
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• v.15 no.3
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• pp.9-19
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• 2001

In this paper we present the aspect of inertial oscillation typically observed in the spin-up of fluids at low Rossby numbers in a circular cylinder. Numerical computations for the quasi three-dimensional equation as well as one-dimensional equation are performed to estimate the predictability of the one-dimensional equation with Ekman pumping/suction models. It is assumed that the discrepancy between the two results may be attributed to the inertial oscillation The detailed analysis to the numerical results reveals that the axial plane is dominated by a comparatively strong oscillatory flows caused by the inertial oscillation. In view of the fact that the time-averaged flow field however agrees to the Taylor-Proudman theorem, it is recommended that further analysis is needed to obtain an improved one-dimensional model like the Reynolds-averaged Navier-Stokes equation for turbulent flows.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.4
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• pp.273-281
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• 2001

In this paper, we report the experimental and numerical results on spin-up flows in a rectangular container of the aspect ratio 2. The Ekman pumping models used in the numerical study are of 1st- and 2nd- order. We also investigate flows obtained without any pumping model. In the experiment, the classical PIV method is used. It is shown that the results given by the 1st-order and 2nd-order models are in good agreement with the experimental result, whereas the non-pumping model shows a significant discrepancy.

• 한국가시화정보학회:학술대회논문집
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• 2004.12a
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• pp.81-90
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• 2004

A zonal embedded grid technique has been developed for computation of the two-dimensional Navier-Stokes equations with cylindrical coordinates. The fundamental idea of the zonal embedded grid technique is that the number of azimuthal grids can be made small near the origin of the coordinates so that the grid size is more uniformly distributed over the domain than with the conventional regular-grid system. The code developed using this technique combined with the explicit, finite-volume method was then applied to calculation of the spin-up flows within a semi-circular cylinder. It was shown that the numerical results were in good agreement with the experimental results both qualitatively and quantitatively.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.71-74
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• 2003

In this paper, we report the numerical and experimental results in a half-cylinder. In the numerical computation, we used the zonal embedded grid system. Flow visualization for the spin-up flows was used by PIV. The results show that at left hand side an cyclonic cell moves along a wall and separates into both cells at right hand side.

• Journal of the Korean Society of Visualization
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• v.2 no.2
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• pp.32-37
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• 2004

In this paper the numerical method with a zonal embedded grid system for an incompressible flow within a semi-circular container is presented. The algorithm is validated by its application to some typical flow models including the spin-up flow inside a semi-circular geometry. Flow visualization for the spin-up flows was used by PIV. The results show that at high Reynolds numbers the cyclonic cell at the left-hand side region moves along the circular wall and merges with the cell at the right-hand side region.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.1 s.244
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• pp.67-73
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• 2006

This investigation deals with the spin-up flows in a circular container of aspect ratio, 2.0. Shear front is generated in the transient spin-up process and propagating from the side wall to the central axis in a rotating container. Propagation of the shear front to the axis in a rotating container means the region acquires an angular momentum transfer from the solid walls. Propagating speed of the shear front depends on the apparent viscosity of polymer solution. Two kinds of polymer solutions are considered as a working fluid: one is CMC and the other is CTAB solution. CMC solution has larger apparent viscosity than that of water, and CTAB shows varying apparent viscosities depending on the applied shear rates. Transient and spatial variations of the apparent viscosities of the present polymer solutions (CTAB and CMC) cause different speeds of the propagating shear front. In practice, CMC solution that has larger values of apparent viscosity than that of water always shows rapid approach to the steady state in comparison of the behavior of the flows with water. However, for the CTAB solution, the speed of the propagating of the shear front changes with the local magnitude of its apparent viscosity. Consequently, the prediction of Wedemeyer's model quantitatively agrees with the present experimental results.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.512-517
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• 2001

In this study, spin-up flows in a rectangular container are analysed by using three-dimensional computation. In the numerical computation, we use the parallel computer system of PC-cluster type. We compared our results with those obtained by two-dimensional computation. Effect of velocity and vorticity on the flow is studied. The result shows that two-dimensional solution is in good agreement with the 3-D result. Attention is given to the region where the 3-D flow is significant.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1765-1770
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• 2003

This paper describes a study of the spin-up of a free-surface fluid in a rectangular container in which an internal cylindrical obstacle is mounted. Experiments and numerical analysis have been carried out for a variety of obstacle position. Increase in the speed of background rotation and near wall position of cylindrical obstacle results in the complex flow structures. Numerical and experimental results agree well with each other and the Ekman-pumping model is also applied to this flow.