• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.30 no.3
• /
• pp.114-122
• /
• 2018

This paper introduces a non-hydrostatic wave model SWASH for simulating wave interactions with porous structures. This model calculates the flow in porous media based on volume-averaged Reynolds-averaged Navier-Stokes equations (VARANS) in ${\sigma}$-coordinate. The empirical coefficients of resistance used to account for the flow in a porous media often need to be measured or calibrated. In this study, the empirical resistance coefficients used in the model are calibrated and validated using laboratory experiments, involving dam-break flow through porous media, and solitary wave interactions with a porous structure. It is shown that the agreement between experimental and numerical results is generally satisfactory. It is also confirmed that non-hydrodynamic model, SWASH, is computationally much more efficient than the three-dimensional porous flow models based on VOF approach.

• Journal of Energy Engineering
• /
• v.28 no.4
• /
• pp.19-28
• /
• 2019

A study has been done on the three dimensional turbulent flow characteristic near the porous wall. The porous holes are considered by penetrating the wall in regular arrangement, and porosity is controlled by diameter of holes. Flow characteristics near the three dimensional porous wall are compared with field test results and self-generated experimental results. FLUENT is employed for computational analysis on the effect of three dimensional porosity with flow and pressure characteristics. As a result, drag coefficient is defined and compared for three dimensional effect. The drag coefficient is mostly a function of porosity, whereas the effect of Reynolds number is minimal, and its correlation is presented in terms of three dimensional porosity.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.10
• /
• pp.667-672
• /
• 2016

The goal of this study was to develop a venturi-type air bubble generator with a porous material throat. Using the two-phase multi-flow CFD analysis for the venturi tube, researchers determined the optimal design of major dimensions, such as the venturi throat length and diameter, in order to control the performance of the air bubble supply through the porous material throat in a venturi tube. Researchers then determined the relationship between the flow rate of supply water and the major design dimensions of the venturi-type air generator for maximizing the performance of the air bubble supply through the porous material throat in a venturi tube.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.9
• /
• pp.855-862
• /
• 2013

A series of 1/5 scale-down reactor flow distribution tests had been conducted to determine the hydraulic characteristics of an APR+ (Advanced Power Reactor Plus), which were used as the input data for an open core thermal margin analysis code. In this study, to examine the applicability of computational fluid dynamics with the porous model to the analysis of APR+ internal flow, simulations were conducted using the commercial multi-purpose computational fluid dynamics software ANSYS CFX V.14. It was concluded that the porous domain approach for some reactor internal structures could adequately predict the flow characteristics inside a reactor in a qualitative manner. If sufficient computational resources are available, the predicted core inlet flow distribution is expected to be more accurate by considering the real geometry of the internal structures, especially upstream of the core inlet.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.9
• /
• pp.781-788
• /
• 2012

Flow in the oxidizer manifold of a liquid rocket combustor has been analysed using an open source CFD toolbox, OpenFOAM. The applicability of OpenFOAM to the problems with complex geometries involving porous media zones for simulating the pressure drop induced by the injectors has been evaluated by performing turbulent, incompressible steady-state flow analysis. The usefulness and applicable area of the OpenFOAM as a design evaluation and analysis tool will be confirmed and enlarged by further evaluation with various computational cases representing major physical phenomena in rocket combustion devices.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2005.06a
• /
• pp.231-238
• /
• 2005

On the basis of flow resistance theory the conceptual model and related mathematical descriptions is proposed for resistance modeling of groundwater flow in CPM(continuum Porous medium), DFN(discrete fracture network) and fractured-porous medium. The proposed model is developed on the basis of finite volume method assuming steady-state, constant density groundwater flow. The basic approach of the method is to evaluate inter-block flow resistance values for a staggered grid arrangement, i.e. fluxes are stored at cell walls and scalars at cell centers. The balance of forces, i.e. the Darcy law, is utilized for each control volume centered around the point where the velocity component is stored. The transmissivity (or permeability) at the interface is assumed to be the harmonic average of neighboring blocks. Flow resistance theory was utilized to relate the fluxes between the grid blocks with residual pressures. The flow within porous medium is described by three dimensional equations and that within an individual fracture is described by a two dimensional equivalent of the flow equations for a porous medium. Newly proposed models would contribute to develop flow simulation techniques with various matrix characteristics.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.8
• /
• pp.537-544
• /
• 2017

The purpose of this study is to analyze the flow characteristics when a staggered hollow fiber membrane module is modeled as a porous medium. The pressure-velocity equation was used for modeling the porous medium, using pressure drop data. In terms of flow characteristics, we compared the case of the "porous medium" when the membrane module was modeled as a porous medium with the case of the "membrane module" when considering the original shape of the membrane module. The difference in pressure drop between the "porous medium" and "membrane module" was less than 0.6%. However, the maximum flow velocity and mean turbulent kinetic energy of the "porous medium" were 2.5 and 95 times larger than those of the "membrane module," respectively. Our results indicate that modeling the hollow fiber module as a porous medium is useful for predicting pressure drop, but not sufficient for predicting the maximum flow velocity and mean turbulent kinetic energy.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.12 no.3
• /
• pp.16-23
• /
• 2008

Flow analyses have been performed to investigate the uniformity of propellant flow through the oxidizer manifold of a 30 tonf full-scaled combustor. Injectors were simulated as porous medium layers of equivalent pressure drops. The uniformity of oxidizer propellant has been analyzed for various diameters of holes in vertical/horizontal distributors and configurations of oxidizer inlet to propose an improved design solution. It has been proven that the mass flow uniformity were improved by adjusting the holes in vertical/horizontal distributors.

• Proceedings of the KSME Conference
• /
• 2005.11a
• /
• pp.81.2-81.2
• /
• 2005

• Journal of the Korean Society of Visualization
• /
• v.20 no.2
• /
• pp.63-69
• /
• 2022

In this study, we numerically simulate the condensational growth of micron-sized particles traveling through a pipe filled with humidified air. Using the finite volume method and Lagrangian particle tracking technique, the mixture of particle-laden flow with moist air in a T-juction pipe is simulated. The condensational growth of particles is calculated by considering the mass transfer of vapor in the air onto the particle surface. The results indicate that the growth rate of the particles increases as the relative humidity of air is higher. Furthermore, the placement of a porous media with low permeability in the pipe could enhance the degree of condensational growth.