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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of computational fluids engineering
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Journal DOI :
Korea Society of Computational Fluids Engineering
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Volume & Issues
Volume 13, Issue 4 - Dec 2008
Volume 13, Issue 3 - Sep 2008
Volume 13, Issue 2 - Jun 2008
Volume 13, Issue 1 - Mar 2008
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DEVELOPMENT OF PREDICTION MODEL OF THE SHAPE OF DEPOSITED PARTICLES APPLIED FOR AEROSOL BASED DIRECT-WRITE TECHNOLOGY
Park, Jun-Jung ; Baek, Seong-Gu ; Rhee, Gwang-Hoon ;
Journal of computational fluids engineering, volume 13, issue 1, 2008, Pages 1~6
Direct Write Technologies are being utilized in various industrial fields such as antennas, engineered structures, sensors and tissue engineering. With Direct Write Technologies, producing features have the mesoscale range, from 1 to 100 microns. One form of the Direct Write Technologies is based on aerosol dynamics. The shape of deposited aerosols determine the form of products in the Direct Write Technology based on aerosol dynamics. To predict shape of deposited aerosol, a prediction model is created. In this study, we estimated Line-Width and Line-Thickness from the prediction model. Results of prediction model is valid from comparison with experimental results.
STUDY ON HIGH RESOLUTION SCHEMES SUITABLE FOR AN 3-D CFD CODE(POWERCFD) USING UNSTRUCTURED CELL-CENTERED METHOD AND INTERFACE CAPTURING METHOD
Myong, H.K. ; Kim, J.E. ;
Journal of computational fluids engineering, volume 13, issue 1, 2008, Pages 7~13
Several high resolution schemes such as OSHER, MUSCL, SMART, GAMMA, WACEB and CUBISTA are comparatively studied with respect to the accurate capturing of fluid interfaces throughout the application to two typical test cases of a translation test and a collapsing water column problem with a return wave. It is accomplished by implementing the high resolution schemes in the in-house CFD code(PowerCFD) for computing 3-D flow with an unstructured cell-centered method and an interface capturing method, which is based on the finite-volume technique and fully conservative. The calculated results show that SMART scheme gives the best performance with respect to accuracy and robustness.
FLOW CHARACTERISTICS AROUND A RUDDER IN OPEN LATER CONDITION
Choi, J.E. ; Kim, J.H. ;
Journal of computational fluids engineering, volume 13, issue 1, 2008, Pages 14~20
The flow characteristics around a rudder in open water condition is analyzed by the computational method. Reynolds averaged Navier-Stoke's equation is utilized for the computation. The computational hydrodynamic force coefficients are verified through comparing with the experimental results. The information of these flow characteristics is necessary to predict cavitation and maneuvering performances, to estimate steering gear capacitance, and to get the bending moment which is useful for the structural analysis. The pressure distribution, the three-dimensional flow separation, and the tip vortices are investigated. The pattern of the three-dimensional flow separation is analyzed utilizing a topological rule. The tip vortices are also investigated through a visualization technique.
LAMINAR FLOW IN THE ENTRANCE REGION OF HELICAL TUBES FOR UNIFORM INLET VELOCITY CONDITIONS
Kim, Y.I. ; Park, J.H. ;
Journal of computational fluids engineering, volume 13, issue 1, 2008, Pages 21~27
A numerical study for laminar flow in the entrance region of helical tubes for uniform inlet velocity conditions is carried out by means of the finite volume method to investigate the effects of Reynolds number, pitch and curvature ratio on the flow development. This results cover a curvature ratio range of 1/10
1/320, a pitch range of 0.0
3.2, and a Reynolds number range of 125
2000. It has been found that the curvature ratio does significantly effect on the angle of flow development, but the pitch and Reynolds number do not. The characteristic angle
, or the non-dimensional length
can be used to represent the flow development for uniform inlet velocity conditions. In uniform inlet velocity conditions, the growth of boundary layer delays the flow development attributed to centrifugal force, and in which conditions the amplitude of flow oscillations is smaller than that in parabolic inlet velocity conditions. If the pitch increases or if the curvature ratio or Reynolds number decreases, the minimum friction factor and the fully developed average friction factor normalized with the friction factor of a straight tube and the flow oscillations decrease.
NUMERICAL SIMULATION OF DAM-BROKEN PROBLEMS USING A PARTICLE METHOD
Lee, B.H. ; Jung, S.J. ; Kim, Y.H. ; Park, J.C. ;
Journal of computational fluids engineering, volume 13, issue 1, 2008, Pages 28~34
A particle method recognized as one of the gridless methods has been developed to investigate the nonlinear free-surface motions interacting to the structures. The method is more feasible and effective than convectional grid methods for solving the non-linear free-surface motion with complicated boundary shapes. The right-handed side of the governing equations for incompressible fluid, which includes gradient, viscous and external force terms, can be replaced by the particle interaction models. In the present study, the developed method is applied to the dam-broken problem on dried- and wet-floor and its adequacy will be discussed by the comparison with the experimental results.
NUMERICAL ANALYSIS OF THREE－DIMENSIONAL SUBSONIC TURBULENT CAVITY FLOWS
Choi, Hong-Il ; Kim, Jae-Soo ;
Journal of computational fluids engineering, volume 13, issue 1, 2008, Pages 35~40
Generally flight vehicles have many cavities such as wheel wells, bomb bays and windows on their external surfaces and the flow around these cavities makes separation, vortex, shock and expansion waves, reattachment and other complex flow phenomenon. The flow around the cavity makes abnormal and three-dimensional noise and vibration even thought the aspect ratio (L/D) is small. The cavity giving large effects to the flow might make large noise, cause structural damage or breakage, harm the aerodynamic performance and stability, or damage the sensitive devices. In this study, numerical analysis was performed for cavity flows by the unsteady compressible three dimensional Reynolds-Averaged Navier-Stokes (RANS) equations with Wilcox's
turbulence model. The MPI(Message Passing Interface) parallelized code was used for calculations by PC-cluster. The cavity has the aspect ratios of 2.5, 3.5 and 4.5 with the W/D ratio of 2 for three-dimensional cavities. The Sound Pressure Level (SPL) analysis was done with FFT to check the dominant frequency of the cavity flow. The dominant frequencies were analyzed and compared with the results of Rossiter's formula and Ahuja& Mendoza's experimental datum.
A STUDY ON THE INTERPOLATION METHODS FOR THE FLUID-STRUCTURE INTERACTION ANALYSIS
Lee, J. ; Kwon, J.H. ;
Journal of computational fluids engineering, volume 13, issue 1, 2008, Pages 41~48
The fluid-structure interaction analysis such as a static aeroelastic analysis requires the result of each analysis as an input to the other analysis. Usually the grids for the fluid analysis and the structural analysis are different, so the results should be transformed properly for each other. The Infinite Plate Spline(IPS) and the Thin Plate Spline(TPS) are used in interpolating the displacement and the pressure. In this study, such interpolation methods are compared with kriging which provides a precise response surface. The static aeroelastic analysis is performed for the supersonic flow field with shock waves and the pressure field is interpolated by the TPS and kriging. The TPS shows tendency to weaken the shock strength, whereas kriging preserves the shock strength.
APPLICATION OF MOVING LEAST SQUARE METHOD IN CHIMERA GRID METHOD
Lee, K. ; Lee, S. ; Cho, J.Y. ;
Journal of computational fluids engineering, volume 13, issue 1, 2008, Pages 49~56
Chimera grid methods have been widely used in Computational Fluid Dynamics due to its simplicity in constructing grid systems over complex bodies, and suitability for unsteady flow computations with bodies in relative motion. However, the interpolation procedure for ensuring the continuity of the solution over overlapped regions fails when the so-called orphan cells are present. We have adopted the MLS(Moving Least Squares) method to replace commonly used linear interpolations in order to alleviate the difficulty associated with the orphan cells. MLS is one of the interpolation methods used in mesh-less methods. A number of examples with MLS are presented to show the validity and the accuracy of the method.
LAMINAR FLOW OVER A CUBOID
Kim, Dong-Joo ;
Journal of computational fluids engineering, volume 13, issue 1, 2008, Pages 57~62
Laminar flows over a cube and a cuboid (cube extended in the streamwise direction) are numerically investigated for the Reynolds numbers between 50 and 350. First, vortical structures behind a cube and lift characteristics are scrutinized in order to understand the variation in vortex shedding characteristics with respect to the Reynolds number. As the Reynolds number increases, the flow over a cube experiences the steady planar-symmetric, unsteady planar-symmetric, and unsteady asymmetric flows. Similar to the sphere wake, the planar-symmetric flow over a cube can be divided into two different regimes: single-frequency regime and multiple-frequency regime. The former has a single frequency due to regular shedding of vortices with the same strength in time, while the latter has multiple frequency components due to temporal variation in the strength of shed vortices. Second, the effect of the length-to-height ratio of the cuboid on the flow characteristics is investigated for the Reynolds number of 270, at which planar-symmetric vortex shedding takes place behind a cube. With the ratio smaller than one, the flow over the cuboid becomes unsteady asymmetric flow, whereas it becomes steady flow for the ratios greater than one. With increasing the ratio, the drag coefficient first decreases and then increases. This feature is related to the flow reattachment on the side faces of the cuboid.