• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년 추계학술대회논문집
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• pp.19-26
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• 2008

From numerical point of view on flow network system analyses, stagnation properties are not preserved along streamlines across geometric discontinuities. Hence, GJM and DTM using ghost cell and thermodynamic relations are developed to preserve the stagnation enthalpy for the boundaries, such as the interfaces between junction and branches and the interface between two pipes of different cross-sections in serial pipelines. Additionally, the resolving power and efficiencies of the 2nd order Godunov type FV schemes are investigated and estimated by the tracing of the total mechanical energy during calculating rapid transients. Among the approximate Riemann solvers, RoeM is more suitable with the proposed boundary treatments especially for junction than Roe's FDS because of its conservativeness of stagnation enthalpy across geometric discontinuities.

• Coupled systems mechanics
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• 제6권3호
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• pp.351-367
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• 2017

In this article, the multiphysics response of magneto-electro-elastic (MEE) cantilever beam subjected to thermo-mechanical loading is analysed. The equilibrium equations of the system are obtained with the aid of the principle of total potential energy. The constitutive equations of a MEE material accounting the thermal fields are used for analysis. The corresponding finite element (FE) formulation is derived and model of the beam is generated using an eight noded 3D brick element. The 3D FE formulation developed enables the representation of governing equations in all three axes, achieving accurate results. Also, geometric, constitutive and loading assumptions required to dimensionality reduction can be avoided. Numerical evaluation is performed on the basis of the derived formulation and the influence of various mechanical loading profiles and volume fractions on the direct quantities and stresses is evaluated. In addition, an attempt has been made to compare the individual effect of thermal and mechanical loading with the combined effect. It is believed that the numerical results obtained helps in accurate design and development of sensors and actuators.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제11권1호
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• pp.95-105
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• 2007

A mathematical modeling for the drying process of hygroscopic porous media, such as wood, has been developed in the past decades. The governing equations for wood drying consist of three conservation equations with respect to the three state variables, moisture content, temperature and air density. They are involving simultaneous, highly coupled heat and mass transfer phenomena. In recent, the equations were extended to account for material heterogeneity through the density of the wood and via the density variation of the material process, capillary pressure, absolute permeability, bound water diffusivity and effective thermal conductivity. In this paper, we investigate the drying behavior for the three primary variables of the drying process in terms of control volume finite element method to the heterogeneous transport model on one-dimensional grid.

• 동력기계공학회지
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• 제13권5호
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• pp.11-17
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• 2009

A numerical study of unsteady mixed convection in a cavity with high viscous fluid is presented. Finite volume method was employed for the discretization and PISO algorithm was used for calculating pressure term. The parameters governing the problem are the Rayleigh number ($10^3\;{\leq}\;Ra\;{\leq}\;10^5$), the Reynolds number (0 < Re $\leq$ 1), and the aspect ratio (0.5 $\leq$ AR $\leq$ 2). The fluid used is silicon oil, a high prandtl number fluid, Pr = 909.1. The results show velocity vectors and temperature distributions. It is found that the periodic flows in a cavity are observed at very low Reynolds numbers, and the period of periodic flow decreases with increasing Reynolds and Rayleigh numbers, and increases with increasing aspect ratio. Also, the Reynolds number range of periodic flow increases with increasing Rayleigh numbers and aspect ratio.

• 소성∙가공
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• 제12권8호
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• pp.693-701
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• 2003

In this paper, the influence of frictional conditions on the backward impact extrusion of aluminum battery casing with large aspect ratio has been investigated. In the simulation, MSC.Superforge, a package based on the finite volume method, is used for the extrusion analysis. The formability and earing problem during the production have been evaluated by studying the sensitivity to frictional effects. During the sensitivity analysis, the friction factor was varied from 0.02 to 0.24. As the friction factor is increased, the forming height of the narrow edge is decreased, and the forming height of the wide edge is increased. When the friction factor becomes 0.2, the earing problem does not occur The experimental results show a good agreement with analytical results.

• 한국해양공학회지
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• 제11권4호
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• pp.141-151
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• 1997

This paper deals with a numerical study of flow-guider applied to controlling current in a bay. Two dimensional numerical model for tidal currents based on the depth averaged equation is developed and standard k-.epsilon. model is adopted to determine the turbulence diffusion. Equations are described in a generalized coordinate system to be implemented by non-staggered grid system and discretized by using finite volume method. Unsteady flow is simulated by fully implicit scheme. Hybrid scheme and central differencing are used to compute the convective terms and source terms, respectively. The tidal current in a rectangular bay is simulated and it gives satisfactory results. The realistic and distinct models of a large structure placed in bay are also exemplified with or without flow-guiders. The simulation results show that the flow-guider gives the residual tidal current in the bay by the different flux with respect to the direction of tidal current.

• 한국전산유체공학회지
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• 제11권1호
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• pp.36-42
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• 2006

The existing numerical approximations of convection flux, especially the spatial higher-order difference schemes, in unstructured cell-centered finite volume methods are examined in detail with each other and evaluated with respect to the accuracy through their application to a 2-D benchmark problem. Six higher-order schemes are examined, which include two second-order upwind schemes, two central difference schemes and two hybrid schemes. It is found that the 2nd-order upwind scheme by Mathur and Murthy(1997) and the central difference scheme by Demirdzic and Muzaferija(1995) have more accurate prediction performance than the other higher-order schemes used in unstructured cell-centered finite volume methods.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.75-77
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• 2011

Thermofluid flow analysis is major subject in most computational fluid dynamics applications. Accompanying convective and conductive heat transport phenomena, radiation plays an important role in high temperature operating systems. Cares in which the radiation dominates are found in such systems as boilers, furnaces, rocket engines, etc. In this paper the finite-volume method (FVM) are employed to simulate two-dimensional radiation problems in concentric and eccentric horizontal cylindrical annuli with general body-fitted coordinates. In that case the simplest and intuitive remedies are proposed for mitigation of ray effect.

• 대한기계학회논문집B
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• 제21권4호
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• pp.541-550
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• 1997

Computational and experimental investigations on the three-dimensional flowfield through an automotive cooling fan are carried out in this work. Steady, incompressible, three-dimensional, turbulent flow through a rotating axial-flow fan is analyzed with Reynolds averaged Navier-Stokes equations and standard k-.epsilon. turbulence model. The governing equations are discretized with finite-volume approximations in non-orthogonal curvilinear coordinates. Computational static pressures on the casing wall agree well with the experimental data which are measured in this work. And, they are sensitive to the change of tip clearance. The flowfield is not significantly affected by the thickness of the blade. The k-.omega. model gives the static pressure rise on the casing wall which is similar to that with the k-.epsilon. model.

• 대한기계학회논문집
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• 제18권10호
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• pp.2762-2772
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• 1994

Branch flows for Newtonian and non-Newtonian fluids are simulated by the finite volume method. The modified power-law model is employed as a constitutive equation of the non-Newtonian fluids. Numerical analyses are focused on understanding of flow patterns for different values of branch angles, diameter ratios and Reynolds numbers. The numerical results are compared with the existing experimental data. The calculated velocity profiles and pressure variations are in good agreement with available experimental results.