• Proceedings of the KSME Conference
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• 2002.08a
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• pp.389-392
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• 2002

In many industrial applications, multiphase flow analysis is the norm rather than an exception as compared to more-conventional single-phase investigation. This paper describes the implementation of the multiphase flow simulation capability in the general purpose CFD software AVL FIRE/SWIFT. The governing equations are discretized based on a finite volume method (FVM) suitable fur very complex geometry, The pressure field is obtained using the SIMPLE algorithm. Depending on the characteristics of the multiphase flow to be examined, the user can choose either the two-fluid model or an explicit interface-tracking model based on the Volume-of-Fluid approach. For truly 'multi'-phase flow problems, it is also possible to apply a hybrid model where certain phases are explicitly tracked while the other phases are handled by the two fluid model. In order to demonstrate the capability of the method, applications to the Taylor bubble flow simulations are presented.

• Journal of the Korean Society of Visualization
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• v.2 no.2
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• pp.8-15
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• 2004

With all the recent progresses in computer hardware and software technology, the animation of fluids in real-time is still among the most challenging issues of computer graphics. The fluid animation is carried out in two steps - the physical simulation of fluids immediately followed by the visual rendering. The physical simulation is usually accomplished by numerical methods utilizing the particle dynamics equations as well as the fluid mechanics based on the Navier-Stokes equations. Particle dynamics method is usually fast in calculation, but the resulting fluid motion is conditionally unrealistic. The methods using Navier-Stokes equation, on the contrary, yield lifelike fluid motion when properly conditioned, yet the complexity of calculation restrains this method from being used in real-time applications. This article presents a rapid fluid animation method by using the continuum-based fluid mechanics and the enhanced particle dynamics equations. For real-time rendering, pre-integrated volume rendering technique was employed. The proposed method can create realistic fluid effects that can interact with the viewer in action, to be used in computer games, performances, installation arts, virtual reality and many similar multimedia applications.

• Journal of Drive and Control
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• v.16 no.1
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• pp.36-44
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• 2019

Variable displacement swash plate piston pump analysis requires electric, hydraulics and dynamics which are similar to the one's incorporated in the complex fluid power and mechanical systems. The main variable capacity for the swash plate piston pumps, hydraulics or simple kinematic (swash plate degree, piston displacement) models are analyzed using AMESim, a multi-physics analysis program. AMESim is a multi-physics hydraulic analysis program that is considered good for the environment but not appropriate for environmental analysis for multibody dynamics. In this study, the analytical model of the swash plate type hydraulic piston pump variable capacity is modeled by combining the hydraulic part and the dynamic part through co-simulation of multibody dynamics program (Virtual.lab Motion) and multi-physics analysis (AMESim). This paper describes the whole modeling analysis method on the mechanical analysis of the multi-body dynamics program and how the hydraulic analysis in multi-physics analysis program works. This paper also presents a methodology for analyzing complex fluid power systems.

• Journal of computational fluids engineering
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• v.18 no.1
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• pp.49-57
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• 2013

Analysis of fluid-structure interaction for two nearby underwater vehicles immersed in the sea is quite challenging because simulation of flow around them is very difficult due to the complexity of underwater vehicle shapes. The conventional approach using body-fitted or unstructured grids demands much time in dynamic grid generation, and yields slow convergence of solution. Since an analysis of fluid-structure interaction must be based on accurate simulation results, a more efficient way of simulating flow around underwater vehicles, without sacrificing accuracy, is desirable. An immersed boundary method facilitates implementation of complicated underwater-vehicle shapes on a Cartesian grid system. An LES modeling is also incorporated to resolve turbulent eddies. In this paper, we will demonstrate the effectiveness of the immersed boundary method we adopted, by presenting the simulation results on the flow around a modeled high-speed underwater vehicle interacting with a modeled low-speed one.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.36-37
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• 2014

It is necessary to develop highly sophisticated Modeling & Simulation (M&S) system for the scientific investigation of marine accident causes and for the systematic reproduction of accidental damage procedure. To ensure an accurate and reasonable prediction of marine accidental causes, such as collision, grounding and flooding, full-scale ship M&S simulations would be the best approach using hydrocode, such as LS-DYNA code, with its Fluid-Structure Interaction (FSI) analysis technique. The objectivity of this paper is to present three full-scale ship collision, grounding and flooding simulation results of marine accidents, and to show the possibility of the scientific investigation of marine accident causes using highly sophisticated M&S system.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.99-102
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• 2002

The present study describes a numerical analysis for simulation of the sloshing of flows with free-surface which contained in a rectangular tank The SOLA-VOF (Volume of fluid) method uses a fixed mesh for calculating the motion of flow and the free-surface. This Eulerian approach enables the VOF method to use only a small amount of computer memory for simulating sloshing problems with complicated free-surface contours. The VOF function, representing the volume fraction of a cell occupied by the fluid, is calculated for each cells, which gives the locating of the free-surface filling any some fraction of cells with fluid. Using SOLA-VOF method, the study describes visualization about simulation of the sloshing of flows and damping effect by baffle. Translation and pitching motion of the forms have been investigated The time-dependent changes of free-surface height are used for visualization subject to several conditions such as fluid height horizontal acceleration, sinusoidal motion, and viscosity. The free-surface heights were used for comparing wall-force, which is caused by sloshing of flows. Baffle was Installed to reduce the force on the wall by sloshing of flows. Damping effects was extensively expressed under the conditions such as baffle shape and position.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.1
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• pp.29-38
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• 2005

The fluid animation procedure consists of physical simulation and visual rendering. In the physical simulation of fluids, the most frequently used practices are the numerical simulation of fluid particles using particle dynamics equations and the continuum analysis of flow via Wavier-Stokes equation. Particle dynamics method is fast in calculation, but the resulting fluid motion is conditionally unrealistic The method using Wavier-Stokes equation, on the contrary, yields lifelike fluid motion when properly conditioned, yet the complexity of calculation restrains this method from being used in real-time applications. Global illumination is generally successful in producing premium-Duality rendered images, but is also excessively slow for real-time applications. In this paper, we propose a rapid fluid animation method incorporating enhanced particle dynamics simulation method and pre-integrated volume rendering technique. The particle dynamics simulation of fluid flow was conducted in real-time using Lennard-Jones model, and the computation efficiency was enhanced such that a small number of particles can represent a significant volume. For real-time rendering, pre-integrated volume rendering method was used so that fewer slices than ever can construct seamless inter-laminar shades. The proposed method could successfully simulate and render the fluid motion in real time at an acceptable speed and visual quality.

• Journal of Navigation and Port Research
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• v.41 no.6
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• pp.451-466
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• 2017

Deep-sea fishing vessel No. 501 Oryong was fully flooded through its openings and sunk to the bottom of the sea due to the very rough sea weather on the way of evasion after a fishing operation in the Bearing Sea. As a result, many crew members died and/or were missing. In this study, a full-scale ship flooding sinking simulation was conducted, and the sinking process was analyzed for the precise and scientific investigation of the sinking accident using highly advanced Modeling & Simulation (M&S) system of Fluid-Structure Interaction (FSI) analysis technique. To objectively secure the weather and sea states during the sinking accident in the Bering Sea, time-based wind and wave simulation at the region of the sinking accident was carried out and analyzed, and the weather and sea states were realized by simulating the irregular strong wave and wind spectrums. Simulation scenarios were developed and full-scale ship and fluid (air & seawater) modeling was performed for the flooding sinking simulation, by investigating the hull form, structural arrangement & weight distribution, and exterior inflow openings and interior flooding paths through its drawings, and by estimating the main tank capacities and their loading status. It was confirmed that the flooding and sinking accident was slightly different from a general capsize and sinking accident according to the simple loss of stability.

• Journal of Drive and Control
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• v.15 no.4
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• pp.67-73
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• 2018

The paper deals with an approach to time domain simulation for closed end at the downstream of pipe, hydraulic lines terminating into a tank and series lines with change of cross sectional area. Time domain simulation of a fluid power systems containing hydraulic lines is very complex and difficult if the transfer functions consist of hyperbolic Bessel functions which is the case for the distributed parameter dissipative model. In this paper, the magnitudes and phases of the complex transfer functions of hydraulic lines are calculated, and the MATLAB Toolbox is used to formulate a rational polynomial approximation for these transfer functions in the frequency domain. The approximated transfer functions are accurate over a designated frequency range, and used to analyze the time domain response. This approach is usefully to simulate fluid power systems with hydraulic lines without to approximate the frequency dependent viscous friction.

• Structural Engineering and Mechanics
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• v.60 no.2
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• pp.225-235
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• 2016

Fluid impact tests on plates containing mesh reinforcement and polypropylene fibers were modeled and simulated using explicit finite element analysis software, LS-DYNA. The scabbing dimensions obtained by the experiments and the simulations were compared and crack formations were matched. The objective was to test the accuracy and fidelity of the model and to confirm that damage caused by fluid impact on the plates can be estimated with a reasonable accuracy over a wide range of impact velocity.