When an oil-spilling accident occurs at sea, it causes tremendous economic loss, and environmental damages. To minimize these marine disasters, predicting the amount of oil-leaking is one of the most important things ...
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When an oil-spilling accident occurs at sea, it causes tremendous economic loss, and environmental damages. To minimize these marine disasters, predicting the amount of oil-leaking is one of the most important things for the quick response and decision making in the early stage of the accident. In the present study, numerical investigation on the oil-leaking phenomena from a two-dimensional damaged tank was carried out to predict the amount of the oil leaking from a leakage hole of a rectangular tank by using the PNU-MPS(Pusan-National-University-modified movingparticlesimulation) method (Lee et al., 2011). As a preliminary test to confirm the accuracy of the PNU-MPS method for the two-phase problem and to investigate the influence of the gradient model, numerical simulations for the Rayleigh-Taylor(R-T) instability were carried out By using an appropriate gradient model and applying a high-order time integration scheme, i.e. 4th-order Runge-Kutta scheme, it was found that the simulation results became closer to the experimental ones (Kim and Lee, 2001), by which the oil-leaking speed and Torricelli's factor relating the speed predicted by using the hydrostatic balance and the real leakage speed were measured and assessed. (C) 2013 Elsevier Ltd. All rights reserved.
When an oil-spilling accident occurs at sea, such as Exxon Valdez Oil Spill (1989) and Oil Spill Off the West Coast of Korea (2007), it causes tremendous economic loss and environmental damages. To minimize these mari...
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ISBN:
(纸本)9781457720918
When an oil-spilling accident occurs at sea, such as Exxon Valdez Oil Spill (1989) and Oil Spill Off the West Coast of Korea (2007), it causes tremendous economic loss and environmental damages. To minimize these marine disasters, predicting the amount of oil-leaking is one of the most important things for the quick response and decision making in the early stage of the accident. In the present study, numerical investigation on the oil-leaking phenomena from a two-dimensional damaged tank was carried out to predict the amount of the oil leaking from a leakage hole of a rectangular tank by using the PNU-MPS(Pusan-National-University-modified movingparticlesimulation) method (Lee at. el., 2011). As a preliminary test to confirm the accuracy of the PNU-MPS method for the two-phase problem and to investigate the influence of the gradient model, numerical simulations for the Rayleigh-Taylor(R-T) instability were carried out. By using the selected gradient model and applying high-order time scheme, i.e. 4th-order Runge-Kutta scheme, it was found that the simulation results became closer to the experimental ones (Kim and Lee, 2001), by which the oil-leaking speed and Torricelli's factor relating the speed predicted by using the hydrostatic balance and the real leakage speed were measured and assessed.
Accumulation of ice on aircraft can lead to severe problems in terms of safety;therefore, development of a method by which these issues can be simulated is required. In this study, the effects of several icing conditi...
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Accumulation of ice on aircraft can lead to severe problems in terms of safety;therefore, development of a method by which these issues can be simulated is required. In this study, the effects of several icing conditions such as inflow velocity, liquid water content, and the angle of attack on the ice accretion on an airfoil are numerically investigated using a particle-based method. The computational target is a NACA0012 airfoil with a chord length of 0.53 m, and droplets with a diameter of 1.0 mm are used in all cases. The icing simulations are carried out with different inflow velocities, liquid water contents, and angle of attack ranging from 50-140 m/s, 0.2-1.6 g/m(3), and -8-20 degrees, respectively, with standard values of 50 m/s, 1.2 g/m(3), and 4 degrees. The explicit moving particle simulation method, which is based on the Lagrangian approach, is employed to obtain complex ice shapes such as feathers. Moreover, aerodynamic performance before and after icing is also compared at different attack angles, using the ice shapes obtained with the movingparticlemethod. It was confirmed that the feather shape, which is difficult to produce with the present lattice method, was reproduced using the particle-based method. The results indicated that icing decreases the stalling angle, and this decrease deteriorates aerodynamic performance by a maximum of 56.2%.
The present paper covers the numerical prediction of the propagation and run-up of a solitary wave over non-flat seabed with various slope angles using a refined MPS (movingparticlesimulation) method. In the refined...
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The present paper covers the numerical prediction of the propagation and run-up of a solitary wave over non-flat seabed with various slope angles using a refined MPS (movingparticlesimulation) method. In the refined method, the corrected gradient model, new staggered divergence-free model, moving-particle wall boundary treatment, and the sub-particle scale turbulence model are applied to obtain more stable and precise results. The simulation results by the developed method are compared with experimental results, and both results were in good agreement. Especially, it can be seen that the complicated and fully-nonlinear behavior of the free-surface motion during the turbulent processes of build-up, break-down, and overturning of the waves are well reproduced by the developed method.
The mechanism of swallowing is still not fully understood, because the process of swallowing is a rapid and complex interaction among several involved organs and the food bolus. In this work, with the aim of studying ...
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The mechanism of swallowing is still not fully understood, because the process of swallowing is a rapid and complex interaction among several involved organs and the food bolus. In this work, with the aim of studying swallowing and aspiration processes noninvasively and systematically, a computer simulationmethod for analyzing the involved organs and water (considered as the food bolus) is proposed. The shape and motion of the organs involved in swallowing are modeled in the same way as in our previous study, by using the Hamiltonian movingparticlesimulation (MPS) method and forced displacements on the basis of motion in a healthy volunteer. The bolus flow is simulated using the explicit MPS method for fluid analysis. The interaction between the organs and the bolus is analyzed using a fluid-structure coupling scheme. To validate the proposed method, the behavior of the simulated bolus flow is compared qualitatively and quantitatively with corresponding medical images. In addition to the healthy motion model, disorder motion models are constructed for reproducing the aspiration phenomenon by computer simulation. The behaviors of the organs and the bolus considered as the food bolus in the healthy and disorder motion models are compared for evaluating the mechanism of aspiration.
The MPS-FE method, which adopts the Finite Element (FE) method for structure computation and the movingparticlesimulation (MPS) method for fluid computation involving free surfaces, was developed to solve fluid-stru...
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The MPS-FE method, which adopts the Finite Element (FE) method for structure computation and the movingparticlesimulation (MPS) method for fluid computation involving free surfaces, was developed to solve fluid-structure interaction problems with free surfaces. The conventional MPS-FE method, in which MPS wall boundary particles and finite elements are overlapped in order to exchange information at a fluid-structure interface, is not versatile and reduces the advantages of the software modularity. In this study, we developed a non-overlapping approach in which the interface in the fluid computation corresponds to the interface in the structure computation through an MPS polygon wall model. The accuracy of the improved MPS-FE method was verified by solving a dam break problem with an elastic obstacle and comparing the result obtained with that of the conventional MPS-FE method and particle FEM.
To determine the relationship among the food bolus velocity, force on epiglottis and swallowing easiness, we carried out swallowing simulation by MPS(movingparticlesimulation)-method using a three-dimensional swallo...
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ISBN:
(纸本)9788494284472
To determine the relationship among the food bolus velocity, force on epiglottis and swallowing easiness, we carried out swallowing simulation by MPS(movingparticlesimulation)-method using a three-dimensional swallowing simulator "Swallow Vision (R)". The configuration and velocity distribution of food bolus (water and thickener), the force on epiglottis by food bolus were visualized by Swallow Vision (R). From simulation results indicated that the average velocity of water was faster than that of the thickener. The velocity distribution of the thickener was narrower than that of water. The force applied by the thickener was greater than that applied by water. It was inffered that there was a relationship between the velocity of a food bolus and swallowing easiness by the difference in velocity distribution of water and the thickener. On the other hand, the force on the epiglottis exhibited a relationship with the swallowing easiness by comparison of water thickener. We believe that Swallow Vision (R) could possibly be applied to evaluations such as evaluations of swallowing easiness and feeling.
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