• Macromolecular Research
• /
• 제11권5호
• /
• pp.393-397
• /
• 2003

By applying a configurational-bias Gibbs ensemble Monte Carlo algorithm, priority simulation results regarding the conformation of non-dilute polyelectrolytes in solvents are obtained. Solutions of freely-jointed chains are considered, and a new method termed strandwise configurational-bias sampling is developed so as to effectively overcome a difficulty on the transfer of polymer chains. The structure factors of polyelectrolytes in the bulk as well as in the confined space are estimated with variations of the polymer charge density.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
• /
• pp.86-87
• /
• 2003

Unstructured grid system is suitable for flows of complex geometries. For problems with moving boundary walls, the grid system must be changed and deformed with time if we use a body fitted grid system. In this paper, a new moving-grid finite-volume method on unstructured grid system is proposed and developed for unsteady compressible flows with shock waves. To assure geometric conservation laws on moving grid system, a control volume on the space-time unified domain is adopted for estimating numerical flux. The method is described and applied for two-dimensional flows.

• Journal of Electrical Engineering and Technology
• /
• 제4권2호
• /
• pp.277-281
• /
• 2009

The complex resonant frequency problem of a superconductor patch is formulated in terms of an integral equation which is the kernel of a dyadic Green's function. To include the effect of the superconductivity of the microstrip patch, the surface complex impedance of the superconductor film is introduced using the two fluids model of Gorter and Casimir. The Galerkin procedure is used in the resolution of the electric field integral equation. Numerical results concerning the effect of the operating temperature of a superconductor patch on the characteristics of the antenna are presented.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2000년도 춘계 학술대회논문집
• /
• pp.51-59
• /
• 2000

The Interactions of shock wave with turbulent boundary layers in high-speed flows cause complex flowfields which result in increased adverse pressure gradients, skin friction and temperature. Accurate and reliable prediction of such phenomena is needed in designing high-speed propulsion systems. Such analyses of the complex flowfields require sophisticated numerical scheme that can resolve interactions between shock wave and boundary layers accurately. Therefore the purpose of the present. article is to introduce an accurate and efficient mixed explicit-implicit generalized Galerkin finite element method. To demonstrate the validity of the theory and numerical procedure, several benchmark cases are investigated.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2005년도 추계 학술대회논문집
• /
• pp.201-206
• /
• 2005

In order to realistically represent the complex turbulence-chemistry interaction at the partially premixed turbulent lifted flames encountered in the gas turbine combustors, the combined conserved-scalar/level-set flamelet approach has been adopted. The parallel unstructured-grid finite-volume method has been developed to maintain the geometric flexibility and computational efficiency for the solution of the physically and geometrically complex flows. Special emphasis is given to the swirl effects on the combustion characteristics of the lean-premixed gas turbine combustor. Numerical results suggest that the present approach is capable of realistically simulating the combustion characteristics for the lean-premixed gas turbine engines and the lifted turbulent jet flame with a vitiated coflow.

• Korea-Australia Rheology Journal
• /
• 제21권4호
• /
• pp.245-268
• /
• 2009

Recent developments in dilute polymer solution rheology are reviewed, and placed within the context of the general goals of predicting the complex flow of complex fluids. In particular, the interplay between the use of polymer kinetic theory and continuum mechanics to advance the microscopic and the macroscopic description, respectively, of dilute polymer solution rheology is delineated. The insight that can be gained into the origins of the high Weissenberg number problem through an analysis of the configurational changes undergone by a single molecule at various locations in the flow domain is discussed in the context of flow around a cylinder confined between flat plates. The significant role played by hydrodynamic interactions as the source of much of the richness of the observed rheological behaviour of dilute polymer solutions is highlighted, and the methods by which this phenomenon can be incorporated into a macroscopic description through the use of closure approximations and multi scale simulations is discussed.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 1995년도 추계 학술대회논문집
• /
• pp.90-103
• /
• 1995

최근 전산 유체 역학은 Navier-Stokes 방정식을 보다 복잡한 유동장 형상에 대해 풀 수 있을 만큼 발달해 왔으나 아직도 유동장 형상이 복잡할 때는 많은 애로를 느끼고 있다. 특히 격자 구성 문제에 있어서 많은 시간과 노력을 기울이고 있으며 심지어 격자 구성 문제를 해결하지 못해 유동해석을 하지 못하는 경우가 많은 실정이다. 따라서 본 연구에서는 주로 내부 유동인 변형 도관를 예로 유동장 형상에 따라 격자구성이 어떻게 달라지는가를 살펴 보았다.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
• /
• pp.228-229
• /
• 2003

Complex flow field around the Darius turbine rotating stationally are simulated by solving the three dimensional incompressible Navier-Stokes equation numerically. The rotating coordinate system is employed so that the boundary conditions on the blades of the rotor become simple. In order to impose the boundary condition on the blades precisely, the boundary fitted coordinate system is employed. Fractional step method is used to solve the basic equations. The complex flow fields due to the three dimensionality of the geometry of the turbine and the rotation of the turbine are obtained and they are visualized effectively by using the technique of the computer graphics.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2007년도 추계 학술대회논문집
• /
• pp.194-199
• /
• 2007

IB (immersed boundary) method is one of the prominent tool in computational fluid dynamics for the analysis of flows over complex geometries. The IB technique simplyfies the solution procedure by eliminating the requirement of complex body fitted grids and it is also superior in terms of memory requirement. In this study we have developed numerical code (FOTRAN) for the analysis of 2D flow over a cylinder using IB technique. The code is validated by comparing the wake lengths and separation angles given by Guo et. al. We employed fractional-step procedure for solving the Navier-Stokes equations governing the flow and discrete forcing IB technique for imposing boundary conditions. Also we have developed a 3D code for the backward-facing-step flow and flow over a sphere. The reattachment length in backward-facing-step flow was compared with the one given by Nie and Armaly, which has proven the validity of our code.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2004년도 추계 학술대회논문집
• /
• pp.53-59
• /
• 2004

A general purpose program NUFLEX for the analysis of 3-D heat/fluid flow in complex geometry with pre/post processor have been developed, which consists of a flow solver based on FVM and a dedicated pre/post processor. The program employs a general non-orthogonal grid system and solve laminar and turbulent (lows with standard and RNG $\kappa-\epsilon$ turbulence models. NUFLEX is capable of analysing two-phase flow with topologically complex interface, turbulent diffusion combustion, solidification problems and magnetic flow. For the purpose of verification of the program and testing the applicability, several practical problems are solved and compared with the available data. Comparison of the NUFLEX results with that by the STAR-CD program has been also made for the same flow configuration and grid structure.