• Journal of applied mathematics & informatics
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• v.16 no.1_2
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• pp.383-405
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• 2004

We study the incomprssible Navier Stokes equations for the flow inside contraction geometry. The governing equations are expressed in the vorticity-stream function formulations. A rectangular computational domain is arised by elliptic grid generation technique. The numerical solution is based on a technique of automatic numerical generation of acurvilinear coordinate system by transforming the governing equation into computational plane. The transformed equations are approximated using central differences and solved simultaneously by successive over relaxation iteration. The time dependent of the vorticity equation solved by using explicit marching procedure. We will apply the technique on several irregular-shapes.

• Journal of computational fluids engineering
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• v.12 no.4
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• pp.68-73
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• 2007

Computational Fluid Dynamics (CFD) approach is now playing an important role in the engineering process in these days. Generating proper grid system in time for the region of interest is prerequisite for the efficient numerical calculation of flow physics using CFD approach. Grid generation is, however, usually considered as a major obstacle for a routine and successful application of numerical approaches in the engineering process. CFD approach based on the unstructured grid system is gaining popularity due to its simplicity and efficiency for generating grid system compared to the structured grid approaches, especially for complex geometries. In this paper an automated triangular surface grid generation using CAD(Computer Aided Design) surface data is proposed. According to the present method, the CAD surface data imported in the STL(Stereo-lithography) format is processed to identify feature edges defining the topology and geometry of the surface shape first. When the feature edges are identified, node points along the edges are distributed. The initial fronts which connect those feature edge nodes are constructed and then they are advanced along the CAD surface data inward until the surface is fully covered by triangular surface grid cells using Advancing Front Method. It is found that this approach can be implemented in an automated way successfully saving man-hours and reducing human-errors in generating triangular surface grid system.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.103-107
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• 2007

Computational Fluid Dynamics (CFD in short) approach is now playing an important role in the engineering process recently. Generating proper grid system for the region of interest in time is prerequisite for the efficient numerical calculation of flow physics using CFD approach. Grid generation is, however, usually considered as a major obstacle for a routine and successful application of numerical approaches in the engineering process. CFD approach based on the unstructured grid system is gaining popularity due to its simplicity and efficiency for generating grid system compared to the structured grid approaches. In this paper an automated triangular surface grid generation using CAD surface data is proposed According to the present method, the CAD surface data imported in the STL format is processed to identify feature edges defining the topology and geometry of the surface shape first. When the feature edges are identified, node points along the edges are distributed. The initial fronts which connect those feature edge nodes are constructed and then they are advanced along the CAD surface data inward until the surface is fully covered by triangular surface grid cells using Advancing Front Method. It is found that this approach can be implemented in an automated way successfully saving man-hours and reducing human-errors in generating triangular surface grid system.

• 한국전산유체공학회:학술대회논문집
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• 2002.10a
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• pp.84-87
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• 2002

When computing the flow around complex three dimensional configurations, the generation of grid is the sunt time consuming part of any calculation. The object of this study is to develop the grid duster techniques capable of resolving complex flows with shock waves, expansion waves, shear layers, and cursive shapes, The Dot insert method of Non-Uniform Rational B-Splines is described as a id control method.

• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.108-114
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• 1999

In this paper. a new automatic multi=block grid generation technique for general 2D regions is introduced. According to this simple and robust method, the domain of interest is first triangulated by using Delaunay triangulation of boundary points, and then geometric information of those triangles is used to obtain block topology. Once block boundaries are obtained. structured grid for each block is generated such that grid lines have $C^0-continuity$ across inter-block boundaries. In the final step of the present method, an elliptic grid generation method is applied to smoothen grid distribution for each block and also to re-locale the inter-block boundaries, and eventually to achieve a globally smooth multi-block structured grid system with $C^1-continuity$.

• Journal of computational fluids engineering
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• v.12 no.3
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• pp.20-28
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• 2007

A fast and robust method of grid generation to multiple functions has been developed for flow analysis in three dimensional space. It is based on the Non-Uniform Rational B-Spline(NURBS) of an approximation method. Many of NURBS intrinsic properties are introduced and much more easily understood. The grid generation method, details of numerical implementation. examples of application, and potential extensions of the current method are illustrated in this paper. The object of this study is to develop the surface grid generation and the grid cluster techniques capable of resolving complex flows with shock waves, expansion waves, shear layers. The knot insert method of Non-Uniform Rational B-Spline seems well worked. In addition, NURBS has been widely utilized to generate grids in the computational fluid dynamics community. Computational examples associated with practical configurations have shown the utilization of the algorithm.

• Journal of computational fluids engineering
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• v.2 no.2
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• pp.18-25
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• 1997

A pressure-based Navier-Stokes numerical solver was used to compare solutions of the k-ε/RNG k-ε turbulence models. An efficient grid generation scheme, the transient grid generation with full boundary control, was used to solve the flows in the tip clearance region. Results indicate that the calculations using k-ε model captures various phenomena related to the tip clearance with good accuracy.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2237-2248
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• 1995

In incompressible flow which has multi-length scale, it has a very important effect which dependent variables are used for adaptive grid generation. Among many length scales in incompressible flow, the dependent variables used for the adaptive grid generation should be able to represent the feature of the concerned system. In this paper, by using vorticity and stream function, in addition to velocity components, the smoother and more stable grid generation is possible and these four flow properties represent each scale. The adaptive grid generation for a lid-driven cavity flow with $N_{re}$ =3200 using four flow properties such as velocity components, vorticity, stream function is performed, and the usefulness of using vorticity and stream function as the indicator for adaptive grid generation is shown.

• 연구논문집
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• s.25
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• pp.67-76
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• 1995

A grid generation algorithm associated with turbomachinery cascade flow fields has been developed. The present grid generation system consists of four separate modules. The system input is made of the results of the preliminary design, i.e., flow-path, aerodynamic conditions along the spanwise direction, and the blade profile data. The grid generation method generates a series of two-dimensional grids in the blade-to-blade passage to build up the three-¬dimensional grid, The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The resultant grids generated from each module of the system are used as the preprocessor for the performance prediction of the turbomachinery blade using Naveir-Stokes method in addition to the blade surface modelling for CAD data. For purposes of illustration, the grid generation system is applied to several complex geometries inculding a turbine rotor with and without a tip flow grid. Application to the blade design of the LP compressor was demonstrated to be very reliable and practical in support of design activities. This customized system are coupled strongly with the design procedure and reduces the man-hours required to predict the aerodynamic performance of the turbomachinery cascades using the CFD technique.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.108-111
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• 2007

A fast and robust method of grid generation to multiple functions has been developed for flow analysis in three dimensional space. It is based on the Non-Uniform Rational B-Spline of an approximation method. The grid generation method, details of numerical implementation. examples of application, and potential extensions of the current method are illustrated in this paper.