Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of computational fluids engineering
Journal Basic Information
Journal DOI :
Korea Society of Computational Fluids Engineering
Editor in Chief :
Volume & Issues
Volume 11, Issue 4 - Dec 2006
Volume 11, Issue 3 - Sep 2006
Volume 11, Issue 2 - Jun 2006
Volume 11, Issue 1 - Mar 2006
Selecting the target year
DEVELOPMENT OF AN UNSTRUCTURED OVERSET MESH METHOD FOR 2-D UNSTEADY VISCOUS FLOW SIMULATION WITH RELATIVE MOTION
Jung Mun-Seung ; Kwon Oh-Joon ;
Journal of computational fluids engineering, volume 11, issue 2, 2006, Pages 1~7
An unstructured overset mesh method has been developed for the simulation of unsteady viscous flow fields around multiple bodies in relative motion. For this purpose, a robust and fast search technique is proposed for both triangle and high-aspect ratio quadrilateral cell elements. The interpolation boundary is defined for data communication between grid systems and an interpolation method is suggested for viscous and inviscid cell elements. This method has been applied to calculate the flow fields around 2-D airfoils involving relative motion. Validations were made by comparing the predicted results with those of experiments or other numerical results. It was demonstrated that the present method is efficient and robust for the prediction of unsteady time-accurate flow fields involving multiple bodies in relative motion.
A CFD ANALYSIS FOR THERMAL MIXING IN A SUBCOOLED WATER UNDER TRANSIENT STEAM DISCHARGE CONDITIONS
Kang H.S. ; Kim Y.S. ; Chun H.G. ; Song C.H. ;
Journal of computational fluids engineering, volume 11, issue 2, 2006, Pages 8~18
A CFD benchmark calculation for a steam blowdown test was performed for 30 seconds to develop the methodology of numerical analysis for the thermal mixing between steam and subcooled water. In the CFD analysis, the grid model simulating the sparger and the IRWST pool were developed by the axisymmetric condition and then the steam condensation phenomena by a direct contact was modelled by the so-called condensation region model. Thermal mixing phenomenon in the subcooled water tank was treated as an incompressible flow, a free surface flow between the air and the water, a turbulent flow, and a buoyancy flow. The comparison of the CFD results with the test data showed a good agreement as a whole, but a small temperature difference was locally found at some locations. The commercial CFD code of CFX4.4 together with the condensation region model can simulate the thermal mixing behavior reasonably well when a sufficient number of mesh distribution and a proper numerical method are adopted.
A STUDY ON THE EFFICIENCY OF AERODYNAMIC DESIGN OPTIMIZATION IN DISTRIBUTED COMPUTING ENVIRONMENT
Kim Y.J. ; Jung H.J. ; Kim T.S. ; Son C.H. ; Joh C.Y. ;
Journal of computational fluids engineering, volume 11, issue 2, 2006, Pages 19~24
A research to evaluate the efficiency of design optimization was carried out for aerodynamic design optimization problem in distributed computing environment. The aerodynamic analyses which take most of computational work during design optimization were divided into several jobs and allocated to associated PC clients through network. This is not a parallel process based on domain decomposition in a single analysis rather than a simultaneous distributed-analyses using network-distributed computers. GBOM(gradient-based optimization method), SAO(Sequential Approximate Optimization) and RSM(Response Surface Method) were implemented to perform design optimization of transonic airfoils and evaluate their efficiencies. dimensional minimization followed by direction search involved in the GBOM was found an obstacle against improving efficiency of the design process in the present distributed computing system. The SAO was found fairly suitable for the distributed computing environment even it has a handicap of local search. The RSM is apparently the most efficient algorithm in the present distributed computing environment, but additional trial and error works needed to enhance the reliability of the approximation model deteriorate its efficiency from the practical point of view.
ASSESSMENT OF URANS AND DES SIMULATIONS FOR TWO-DIMENSIONAL BACKWARD FACING STEP FLOW
Song C.S. ; Park S.O. ;
Journal of computational fluids engineering, volume 11, issue 2, 2006, Pages 25~31
A two-dimensional backward facing step flow is simulated by using URANS and Detached Eddy Simulations(DES) approaches. Turbulence models adopted for URANS and DES simulations are Spalart-Allmaras(S-A) model and Shear Stress Transport(SST) model. The target flow with ER=1.125,
is experimentally studied by Driver & Seegmiller. Various versions of DES have been tested in this paper. Results of the simulations are compared with the experimental data available to evaluate the merits and demerits of URANS and several versions of DES. URANS simulation converges to a steady state and hence unsteady characteristics are not featured. DES simulations in general successfully mimic large scale structures and oscillation characteristics of the flow.
A SATELLITE ELECTRONIC EQUIPMENT THERMAL ANALYSIS USING SEMI-EMPERICAL HEAT DISSIPATION METHOD
Kim Jung-Hoon ; Jun Hyung-Yoll ; Yang Koon-Ho ;
Journal of computational fluids engineering, volume 11, issue 2, 2006, Pages 32~39
A heat dissipation modeling method of EEE parts is developed for thermal design and analysis of an satellite electronic equipment. The power consumption measurement value of each functional breadboard is used for the heat dissipation modeling method. For the purpose of conduction heat transfer modeling of EEE parts, surface heat model using very thin ignorable thermal plates is considered instead of conventional lumped capacity nodes. These modeling methods are applied to the thermal design and analysis of CTU EM and EQM and verified by thermal cycling and vacuum tests.
ANALYSIS ON COMPRESSIBLE FLOW WITHIN A SWIRL INJECTOR
Suh Y.K. ; Kang S.M. ; Heo H.S. ;
Journal of computational fluids engineering, volume 11, issue 2, 2006, Pages 40~48
In the present, The theoretical and numerical results of gas flow characteristics inside a swirl injector are presented. For this purpose a one-dimensional (theoretical) model and 2D/3D CFD models are proposed for use in the design of the injector. It was found that contradictory to the classical theory about the compressible flow, the swirl has a significant effect on the mass flow rate and the choking conditions. It was found that the one-dimensional model provides reasonably accurate results compared with the 2D/3D numerical results, and thus can be used at the initial stage of the swirl-injector design process.
OSCILLATORY THERMAL CONVECTION IN A HORIZONTAL ANNULUS
Yoo Joo-Sik ;
Journal of computational fluids engineering, volume 11, issue 2, 2006, Pages 49~55
This study investigates the oscillatory thermal convection of a fluid with Pr=0.02 in a wide-gap horizontal annulus with constant heat flux inner wall. When Pr=0.02, dual steady-state flows are not found. After the first Hopf bifurcation from a steady to a time-periodic flow, five successive period-doubling bifurcations are recorded before chaos. The power spectrum shows the
flows clearly, and a window of period
flow is found in the chaotic regime. The approximate value of the Feigenbaum number for the last three period-doubling bifurcations is 4.76. The transition route to chaos of the present simulations is consistent with the period-doubling route of Feigenbaum.
CONTROL OF A 3-DIMENSIONAL POSTPROCESSING SOFTWARE USING DATA GLOVES FOR IMMERSIVE ENVIRONMENT
Kim K.Y. ; Kim B.S. ;
Journal of computational fluids engineering, volume 11, issue 2, 2006, Pages 56~61
As the size and dimension of target problems in the field of computational engineering including CFD gets bigger and higher, it is needed to have more efficient and flexible data visualization environment in terms of software and hardware. Even though it is still manageable to use a mouse in controlling 3-dimensional data visualization, it would be beneficial to use 3-D input device for 3-D visualization. 'Data Glove' is one of the best 3-D input devices, because human hands are best tools for understanding 3-D space and manipulating 3-D objects. Signals coming from 'Data Glove' are analog and very sensitive to finger motions, therefore signal filtering using a digital filter is applied. This paper describes our experience and benefits of using data gloves in controlling 3-dimensional postprocessing softwares.
EFFICIENT HOLE FINDING METHOD FOR OVERSET GRID SYSTEM
Kim B.S. ; Ko S.H. ;
Journal of computational fluids engineering, volume 11, issue 2, 2006, Pages 62~66
In this paper an automated hole-finding method for overset grids is introduced which uses recursive octree-cell division. A graphic program which enables the user to do the hole-cutting with ease is also introduced. Using this program it is found that there is an optimum combination of the level of octree division and vector calculation for the efficient and fast hole finding.