• International Journal of Highway Engineering
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• v.19 no.6
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• pp.13-21
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• 2017

PURPOSES : In this research, an SB3-level roadside barrier for a highway transition zone that meets the newly established guide Installation and Management Guide for Roadside Safety Appurtenance is developed. Its performance is evaluated by a numerical simulation and real-scale vehicle impact test. METHODS : The commercial explicit dynamic software LS-DYNA is utilized for impact simulation. An FE model of a passenger vehicle developed and released by the National Crash Analysis Center (NCAC) at George Washington University and a heavy goods vehicle (HGV) model developed by the TC226/CM-E Work Group are utilized for impact simulation. The original vehicle models were modified to reflect the conditions of test vehicles. The impact positions of the passenger vehicle and truck to the transition guardrail were set as 1/2 and 3/4 of the transition region, respectively, according to the guide. RESULTS : Based on the numerical simulation results of the existing transition barrier, a new structural system with improved performance was suggested. According to the result of a numerical simulation of the suggested structural system, two sets of transition barriers were manufactured and installed for real-scale vehicle impact tests. The tests were performed at a test field for roadside safety hardware of the Korea Highway Corporation Research Institute. CONCLUSIONS : The results of both the real-vehicle impact tests and numerical simulations of the developed transition barrier satisfied the performance criteria, and the results of numerical simulation showed good correlation with the test results.

• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.2
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• pp.52-60
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• 2009

The purpose of this research is to develop high efficiency plastic plate heat exchangers which can be substituted for conventional aluminum plate heat exchangers. Four simulation models of plastic plate heat exchangers are designed and simulated: that is, flat plate type, turbulent promoter type, corrugate type and dimple type heat exchanger. The flat plate type is designed as the reference model in order to evaluate how much thermal performance increases. The turbulent promoter type is fabricated with cylindrical-type vortex generators and rib-type turbulent promoters. The corrugate type is obtained from the conventional stainless steel compact heat exchangers, which are called the herringbone-type compact heat exchangers. The dimple type has a number of dimples on its surface. In this study, the flow and heat transfer characteristics of the plastic plate heat exchanger are investigated using numerical simulation and compared with experimental results. Numerical simulation is carried out using the FLUENT code. The flows are assumed as a three-dimensional, incompressible and turbulent model. The computational analysis and experimental results both show that the friction coefficient and Nu number is highest in the corrugate type. The tendency of numerical simulation results is in good agreement with that of the experimental results.

• Advances in aircraft and spacecraft science
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• v.10 no.4
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• pp.347-368
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• 2023

In the first part of this study, a numerical simulation model was developed using the mechanical APDL software to validate the results of the 3D-elastisity theory on the laminated sandwich plate developed by Panago. The numerical simulation model showed a good agreement to the results of Pagano's theory in terms of deflection, normal stresses, and shear stresses. In the second part of this study, the developed numerical simulation model was used to define different plates dimensions and fibers layup orientations to examine the load response in terms of deflection and stresses. Further analysis was implemented on the natural frequencies of laminated xxx plates of the plates. The layup configurations include Unidirectional (UD), Cross-Ply (CP), Quasi-Isotropic (QI), the linear bio-inspired known as Linear-Helicoidal (LH), and the nonlinear bio-inspired known as Fibonacci-Helicoidal (FH). The following numerical simulation model can be used for the design and study of novel, sophisticated bio-inspired composite structures in a variety of configurations subjected to sinusoidal or constant loads.

• Journal of computational fluids engineering
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• v.13 no.4
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• pp.96-106
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• 2008

We review a series of studies on turbulent skin friction drag reduction in wall-turbulence recently conducted in Japan. First, an identity equation relating the skin friction drag and the Reynolds shearstress (the FIK identity) is introduced. Based on the implication of the FIK identity, a new analytical suboptimal feedback control law requiring the streamwise wall-shear stress only is introduced and direct numerical simulation (DNS) results of turbulent pipe flow with that control is reported. We also introduce DNS of an anisotropic compliant surface and parameter optimization using an evolutionary optimization technique.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.341-344
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• 2012

The prediction performance of the chemical kinetics for the numerical simulation of MILD combustion was investigated. A wall-confined turbulent methane jet combustor was adopted as a configuration. Four chemical kinetics, such as a global 3-step, WD4, Skeletal, and DRM-19, were investigated, The air stream of the wall-confined MILD jet combustor was diluted with combustion products. It was found that the DRM-19 was optimal for the numerical simulation of the MILD combustion.

• Journal of ILASS-Korea
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• v.5 no.4
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• pp.12-32
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• 2000

The recent trends in numerical simulation of various spray phenomena are reviewed in this article. Major subtopics are atomization/breakup, collision/coalescence, wall collision, interfacial transfer, droplet dispersion, two-phase injection and spray combustion. Each submodel has been under continuous refinement and validation against more extensive data base by advanced laser diagnostic techniques. Most uncertainty in current spray simulations come from these physical submodels, not from excessive computational constraints.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.75-76
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• 2003

Direct numerical simulation results of aeolian tones generated by a two-dimensional obstacle (circular cylinder, square cylinder, NACA0012 airfoil) in a uniform flow are presented and the generation and propagation mechanisms of the sound are discussed. The unsteady compressible Navier-Stokes equations are solved by a highly-accurate finite difference scheme over the entire region from near to far fields. The direct numerical simulation results are also compared with the results obtained by Curle's acoustic analogy.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.347-354
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• 2008

We introduce a series of studies on turbulent skin friction drag reduction in wall-turbulence. First, an identity equation relating the skin friction drag and the Reynolds shear stress (the FIK identity) is introduced. Based on the implication of the FIK identity, a new analytical suboptimal feedback control law requiring the streamwise wall-shear stress only is introduced and direct numerical simulation (DNS) results of turbulent pipe flow with that control is reported. We also introduce DNS of an anisotropic compliant surface and parameter optimization using an evolutionary optimization technique.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.347-354
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• 2008

We introduce a series of studies on turbulent skin friction drag reduction in wall-turbulence. First, an identity equation relating the skin friction drag and the Reynolds shear stress (the FIK identity) is introduced. Based on the implication of the FIK identity, a new analytical suboptimal feedback control law requiring the streamwise wall-shear stress only is introduced and direct numerical simulation (DNS) results of turbulent pipe flow with that control is reported. We also introduce DNS of an anisotropic compliant surface and parameter optimization using an evolutionary optimization technique.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.5-9
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• 2003

Stress and deflection of Active Fiber Composite(AFC) embedded and/or attached composite structures are numerically investigated at the constituent level by the Direct Numerical Simulation(DNS). The DNS approach which models and simulates the fiber and matrix directly using 3D finite elements need to be solved by efficient way. To handle this large scale problem, parallel program for solving piezoelectric behavior was developed and run on the parallel computing environment. Also, the stress result from DNS approach is compared with that from uniform field model.