• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1997.11a
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• pp.43-48
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• 1997

The smoke filling process for the atrium space containing a fire source is simulated using two types of deterministic fire modus: Zone model and Field model. The zone mode used is the CFAST(version 1.6) mode developed at the Building and Fire Research laboratories, NIST in the USA. The lied model is a self-developed fire field model based on Computational Fluid Dynamics(CFD) theories. This article is focused on finding out the smoke movement and temperature distribution in atrium space which is cubic in shape. A computational procedure for predicting velocity and temperature distribution in fro-induced flow is based on the solution, in finite volume method and non-staggered grid system, of 3-dimensional equations for the conservation of mass, momentum, energy, species and so forth. The fire model i. e. Zone model and Field model predicted similar results for Ire clear height and the smoke layer temperature.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.11
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• pp.1453-1463
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• 1999

An electromagnetic flowmeter, based on a magnetic induction principle; provides an obstructionless flowmeter that essentially averages the velocity distribution over the pipe cross-sectional area. To predict the installation effects, the flowmeter installed near $90^{\circ}$ elbow is simulated by using a commercial code FLUENT(ver. 4.48) for the laminar flow field and a code developed through this study for magnetic field. The installation effects of the flowmeter are estimated by varying a number of the dependent parameters such as the radius of the elbow(Rc=1D, 1.5D, 2D, 3D), the location, Reynolds number and the direction of electrodes plane(${\varphi}$). It was found that all these factors affect the performance of the electromagnetic flowmeter significantly. The longer installation distance from the elbow is not always optimal to minimize the error, and also there exists an optimal location to install the EMF for a minimum error. Especially the flow signal with the electrodes plane direction of ${\varphi}=45^{\circ}$ is shown to yield smallest measurement error regardless of the Reynolds number and the curvature of elbow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1265-1272
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• 2011

We performed numerical simulations of the recirculation flow of an electrolyte fluid in a circular container driven by an AC electromagnetic force for solving continuity and momentum equations. We also conducted an experiment to obtain flow data, which were in good agreement with the numerical simulation results. Furthermore, we performed a parametric study on both numerical and experimental aspects and found that the fluid velocity increases with an increase in the electrolyte concentration and magnetic intensity and with a decrease in the fluid depth and AC frequency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.10
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• pp.1365-1372
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• 2001

In the planar flow casting(PFC) process, the conditions of the melt puddle between nozzle and rotating wheel affect significantly the quality and dimensional uniformity of the downstream ribbon. For stable puddle formation, the nozzle is placed very close to the quenching wheel, so the surface-tension and wall-adhesion forces have an important effect upon the fluid flow.\`In this study the planar flow casting process has been mode]ed using the VOF method for free surface tracking. The transient puddle formation from the present analysis shows good agreements with the previous experimental results. Furthermore, the variation of melt temperature and the corresponding cooling rate of the melt have been examined. The present results also show how the melt puddle can be farmed on the rotating substrate, how the melt flows within the puddle, and how the changes of the process variables affect the puddle formation and its corresponding fluid flow and heat transfer behavior.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.4
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• pp.148-157
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• 1997

In this paper, the flow around a V-shaped plate positioned against horizontal flow is numerically simulated by using finite volume method and experimentally visualized in two dimensional tank by dye injection method. The upwelling flow artificially induced by V-shaped plate mixes the stratified stagnant flow. It can be applied to mitigate the eutrophication and stratification of sea in the vicinity of offshore structures.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.3
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• pp.205-211
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• 2005

In this study, a new numerical procedure for the generation of a nonlinear tailored group of waves is presented. The procedure is based on the transient wave group technique. In order to integrate the nonlinearity during the wave propagation in the computational method, the Navier-Stokes equations are applied as governing equations. The governing equations are discretized by finite volume approximation. The deformation of the free water surface in each time step is pursued with a moving grid. A two-dimensional, numerical wave tank for the simulation of the wave propagation is developed and tested in detail. The numeric results are compared first with analytical wave theories and with measurements, in order to examine the correctness of the numerical wave tank. Wave surface elevation and associated fields of velocity and pressure are numerically computed and compared with measurements. Very good agreements show up.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.109-112
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• 1995

The three dimensional, steady flows of blood and blood analogue fluids in the abdominal aortic bifurcation are simulated using the finite volume method. The objective of this investigation is to understand the generation and progression of site-specific atherosclerosis from a hydrodynamic point of view. Due to complexity of blood in conducting experimental study, aqueous polymer solutions are used as the substitutional fluids. For comparison purpose of the flow characteristics of blood and substitutional fluids, rheologically different fluids such as water soluble polymers of Carbopol-934 and Separan AP-273 are employed for the numerical simulation. In order to understand the role of hydrodynamics in the formation and development of atherosclerosis lesions flow velocities, pressures and shear stresses along the vessel are calculated for steady flows.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.37-47
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• 1999

A Finite Volume Method for the discretization of the two-dimensional incompressible Navier-Stokes equation is used to analyse water entry & exit problems in a generalized coordinate system. The free-surface deformations generated by the water entry or exit of a rigid body are simulated by the Level-Set scheme[11]. In the water entry problems for a wedged section and a flared-ship section, the calculation results of water impact force are compared with the experimental results[5] and the time varying free-surface deformations and flow characteristics of the water exit of a cylinder are investigated.

• Journal of computational fluids engineering
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• v.16 no.4
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• pp.39-46
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• 2011

A numerical study of a turbulent natural convection in an enclosure with the lattice Boltzmann method (LBM) is presented. The primary emphasis of the present study is placed on investigation of accuracy and numerical stability of the LBM for the turbulent natural convection flow. A HYBRID method in which the thermal equation is solved by the conventional Reynolds averaged Navier-Stokes equation method while the conservation of mass and momentum equations are resolved by the LBM is employed in the present study. The elliptic-relaxation model is employed for the turbulence model and the turbulent heat fluxes are treated by the algebraic flux model. All the governing equations are discretized on a cell-centered, non-uniform grid using the finite-volume method. The convection terms are treated by a second-order central-difference scheme with the deferred correction way to ensure accuracy and stability of solutions. The present LBM is applied to the prediction of a turbulent natural convection in a rectangular cavity and the computed results are compared with the experimental data commonly used for the validation of turbulence models and those by the conventional finite-volume method. It is shown that the LBM with the present HYBRID thermal model predicts the mean velocity components and turbulent quantities which are as good as those by the conventional finite-volume method. It is also found that the accuracy and stability of the solution is significantly affected by the treatment of the convection term, especially near the wall.

• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.15-28
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• 1998

As an alternative for solving the incompressible Navier-Stokes equations, we present a vorticity-based integro-differential formulation for vorticity, velocity and pressure variables. One of the most difficult problems encountered in the vorticity-based methods is the introduction of the proper value-value of vorticity or vorticity flux at the solid surface. A practical computational technique toward solving this problem is presented in connection with the coupling between the vorticity and the pressure boundary conditions. Numerical schemes based on an iterative procedure are employed to solve the governing equations with the boundary conditions for the three variables. A finite volume method is implemented to integrate the vorticity transport equation with the dynamic vorticity boundary condition . The velocity field is obtained by using the Biot-Savart integral derived from the mathematical vector identity. Green's scalar identity is used to solve the total pressure in an integral approach similar to the surface panel methods which have been well-established for potential flow analysis. The calculated results with the present mettled for two test problems are compared with data from the literature in order for its validation. The first test problem is one for the two-dimensional square cavity flow driven by shear on the top lid. Two cases are considered here: (i) one driven both by the specified non-uniform shear on the top lid and by the specified body forces acting through the cavity region, for which we find the exact solution, and (ii) one of the classical type (i.e., driven only by uniform shear). Secondly, the present mettled is applied to deal with the early development of the flow around an impulsively started circular cylinder.