• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.147-148
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• 2022

Due to recent climate abnormalities, the form of rainfall is changing to localized torrential rains. Localized torrential rains cause flooding in urban areas. In addition, in various industrial fields, there are cases where materials necessary for the process are kept outdoors, and damage from material loss and flooding of stockyards occurs during heavy rain. Accordingly, it is necessary to introduce a drainage layer where flooding is expected. This drainage layer places the aggregate inside and allows rainwater to penetrate and drain into the voids between the aggregates. However, the amount of voids differs according to the particle size distribution and particle size of the aggregate, and the drainage performance varies according to the compositional location of the aggregate. Therefore, in this study, the drainage characteristics according to the particle size, particle size, and compositional location of aggregates are analyzed using a fluid analysis program.

• Journal of the Korea Computer Graphics Society
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• v.23 no.1
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• pp.25-32
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• 2017

This paper proposes a novel acceleration method for particle based large scale fluid simulation. Traditional particle-based fluid simulation has been implemented by interacting with physical quantities of neighbor particles through the Smoothed Particle Hydrodynamics(SPH) technique[1]. SPH method has the characteristic that there is no visible change compared to the computation amount in a part where the particle movement is small, such as a calm surface or inter-fluid. This becomes more prominent as the number of particles increases. Previous work has attempted to reduce the amount of spare computation by adaptively dividing each part of the fluid. In this paper, we propose a technique to calculate the motion of the entire particles by using the physical quantities of the near sampled particles by sampling the particles inside the fluid at regular intervals and using them as reference points of the fluid motion. We propose a technique to adaptively generate a triangle map based on the position of the sampled particles in order to efficiently search for nearby particles, and we have been able to interpolate the physical quantities of particles using the barycentric coordinate system. The proposed acceleration technique does not perform any additional correction for two classes of fluid particles. Our technique shows a large improvement in speed as the number of particles increases. The proposed technique also does not interfere with the fine movement of the fluid surface particles.

• The Journal of Korean Institute of Next Generation Computing
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• v.15 no.4
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• pp.51-61
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• 2019

In this paper, we have implemented soil simulation using fluid simulation technology. A widely used NVIDIA FleX was used to represent the soil generated by excavation work. FleX is a particle-based physics simulation library that combines SPH (Smoothed-particle hydrodynamics) and Position Based Dynamics techniques. However, since the soil has not only fluid properties but also non-fluid properties, it is difficult to simulate with the functions provided by conventional FleX. In this study, we added a technique to simulate non-fluid behavior using existing Flex. This can lead to effective results improvement at low cost.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.5
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• pp.425-433
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• 2015

In this paper, we have numerically investigated two-dimensional dielectrophoretic (DEP) motions of a single particle suspended freely in a viscous fluid, interacting with a nearby nonconducting planar wall, under an externally applied uniform direct-current electric field. Particularly, we solve the Maxwell equation with a large sharp jump in the electric conductivity at the particle-fluid interface and then integrate the Maxwell stress tensor to compute the DEP force on the particle. Results show that, under an electric field parallel to the wall, one particle is always repelled to move far away from the wall and the motion depends strongly on the particle-wall spacing and the particle conductivity. The motion strength vanishes when the particle is as conductive as the fluid and increases as the conductivity deviates further from that of the fluid.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.11-19
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• 2005

First, methods of numerical analysis of gas-particle flows is classified into micro, meso and macro scale approaches based on the concept of multi-scale mechanics. Next, the explanation moves on to discrete particle simulation where motion of individual particles is calculated numerically using the Newtonian equations of motion. The author focuses on the cases where particle-to-particle interaction has significant effects on the phenomena. Concerning the particle-to-particle interaction, two cases are considered: the one is collision-dominated flows and the other is the contact-dominated flows. To treat this interaction mathematically, techniques named DEM(Distinct Element Method) or DSMC (Direct Simulation Monte Carlo) have been developed DEM, which has been developed in the field of soil mechanics, is useful for the contact -dominated flows and DSMC method, developed in molecular gas flows, is for the collision-dominated flows. Combining DEM or DSMC with CFD (computer fluid dynamics), the discrete particle simulation becomes a more practical tool for industrial flows because not only the particle-particle interaction but particle-fluid interaction can be handled. As examples of simulations, various results are shown, such as hopper flows, particle segregation phenomena, particle mixing in a rotating drum, dense phase pneumatic conveying, spouted bed, dense phase fluidized bed, fast circulating fluidized bed and so on.

• Journal of the Korea Computer Graphics Society
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• v.14 no.4
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• pp.1-5
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• 2008

In this paper, we propose an efficient technique for improving the grid based fluid simulation by sub-grid visuals. The detailed turbulency generated efficiently by Vortex Particle Method are blended with the flow fields coming from the traditional incompressible Navier-Stokes solver. The algorithm enables large- and small- scale detail to be edited separately.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.1
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• pp.132-139
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• 1997

Spray characteristics of external mixing sonic twin-fluid atomization nozzles are investigated experimentally. Particle sizes are measured by the Fraunhofer diffraction method using the Malvern particle analyzer, and their radial distributions are obtained using the tomographical transformation technique. The spatial distribution of SMD shows that the drop size increases in the radial direction at a fixed liquid flow rate, and the distribution is getting uniform rapidly as the atomizing gas pressure increases. The SMD decreases as the liquid flow rate increases at a fixed GLR. It is found that the atomization efficiency of the flush type sonic nozzle is superior to that of protrusion type. The effect of laser beam diameter of the particle analyzer on the spatial SMD distribution is minor at present experimental conditions.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.498-501
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• 2009

Electrophoretic displays (EPDs) are attracting considerable attentions as a paper-like display. Especially, Electrophoretic cell consists of micron-sized, charged particles dispersed in a viscous fluid. When an external electric field is applied, the charged particles move with a speed proportional to the particle mobility and the local field strength. In electrophoretic displays fast switching times are required, so knowing the particle mobility is very important. In this paper, we study a novel simulation for calculating the particle motions submerged in a viscous fluid for horizontal switching electrophoretic cell.

• The KSFM Journal of Fluid Machinery
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• v.17 no.6
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• pp.44-51
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• 2014

The disinfection method using UV has emerged as photodissociation in water disinfection. In order to predict performance for UV disinfection, CFD analysis was performed due to saving cost. Most CFD studies of UV reactor have used particle tracking method. However it demands additional analysis time, computing resource and phase besides working fluid. In this paper, pathogenic microorganisms' route is assumed to streamline of fluid to save computing time. the computational results are in good agreement with experimental results. The results of streamline method are compared with the particle tracking method. In conclusion, the effectiveness of streamline method for UV disinfection are confirmed.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.445-452
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• 2019

Shear thickening is an intriguing phenomenon in the fields of chemical engineering and rheology because it originates from complex situations with experimental and numerical measurements. This paper presents results from the numerical modeling of the particle-fluid dynamics of a two-dimensional mixture of colloidal particles immersed in a fluid. Our results reveal the characteristic particle behavior with an application of a shear force to the upper part of the fluid domain. By combining the lattice Boltzmann and discrete element methods with the calculation of the lubrication forces when particles approach or recede from each other, this study aims to reveal the behavior of the suspension, specifically shear thickening. The results show that the calculated suspension viscosity is in good agreement with the experimental results. Results describing the particle deviation, diffusivity, concentration, and contact numbers are also demonstrated.