• Structural Engineering and Mechanics
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• v.36 no.4
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• pp.499-511
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• 2010

This paper examines the ice cover effects on the seismic response of concrete gravity dam-reservoir-foundation interaction systems subjected to a horizontal earthquake ground motion. ANSYS program is used for finite element modeling and analyzing the ice-dam-reservoir-foundation interaction system. The ice-dam-reservoir interaction system is considered by using the Lagrangian (displacementbased) fluid and solid-quadrilateral-isoparametric finite elements. The Sariyar concrete gravity dam in Turkey is selected as a numerical application. The east-west component of Erzincan earthquake, which occurred on 13 March 1992 in Erzincan, Turkey, is selected for the earthquake analysis of the dam. Dynamic analyses of the dam-reservoir-foundation interaction system are performed with and without ice cover separately. Parametric studies are done to show the effects of the variation of the length, thickness, elasticity modulus and density of the ice-cover on the seismic response of the dam. It is observed that the variations of the length, thickness, and elasticity modulus of the ice-cover influence the displacements and stresses of the coupled system considerably. Also, the variation of the density of the ice-cover cannot produce important effects on the seismic response of the dam.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2489-2494
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• 2008

The two-dimensional circular cylinder freely falling in a channel has been simulated by using Immersed boundary - lattice Boltzmann method in order to analyze the characteristics of motion originated by the interaction between the fluid and the solid. The wide range of the solid/fluid density ratio has been considered to identify the effect of the solid/fluid density ratio on the motion characteristics such as the falling time, the terminal velocity and the trajectory in the vertical and horizontal directions. In addition, the effect of the gap between the cylinder and the wall on the motion of two-dimensional circular cylinder freely falling has been revealed by taking into account a various range of the gap size. The Reynolds number in terms of the terminal velocity is diminished as the cylinder becomes close to the wall at the initial dropping position, since the repulsive force induced between the cylinder and wall constrains the vertical motion. Quantitative information about the flow variables such as the pressure coefficient and vorticity on the cylinders is highlighted.

• Journal of computational fluids engineering
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• v.9 no.2
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• pp.43-51
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• 2004

Interaction between fluid flow and thermal radiation has received considerable attention due to its numerous applications in engineering field. In this case the thermofluid properties of radiating fluid vary with the variation of temperature field caused by absorption and emission of radiant heat. To analyze the radiation heat transfer in radiating fluid, the simultaneous solution of the radiative transfer equation (RTE) and the fluid dynamics equations is required. This means that the numerical procedure used for the RTE must be computationally efficient to permit its inclusion in the other submodels, and must be compatible with the other transport equations. The finite volume method (FVM) and the discrete ordinates method (DOM) are usually employed to simulate radiation problems in generalized coordinates. These two representative methods are examined and compared, especially in view of the numerical integration of the radiation intensity over solid angle. The FVM shows better accuracy than the DOM owing to less constraints of the selection of control angle.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.62-70
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• 2004

Interaction between fluid flow and thermal radiation has received considerable attention due to its numerous applications in engineering field. In this case the thermofluid properties of radiating fluid vary with the variation of temperature field caused by absorption and emission of radiant heat. To analyze the radiation heat transfer in radiating fluid, the simultaneous solution of the radiative transfer equation (RTE) and the fluid dynamics equations is required. This means that the numerical procedure used for the RTE must be computationally efficient to permit its inclusion in the other submodels, and must be compatible with the other transport equations. The finite volume method (FVM) and the discrete ordinates method (DOM) are usually employed to simulate radiation problems in generalized coordinates. These two representative methods are examined and compared, especially in view of the numerical integration of the radiation intensity over solid angle. The FVM shows better accuracy than the DOM owing to less constraints of the selection of control angle.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.1081-1090
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• 2024

The liquid Lead-bismuth eutectic is used as the coolant for Gen-IV reactor concepts. However, due to its strong corrosive and high operating temperature, it is difficult to accurately measure the flow rate in long-term operating conditions. Venturi flowmeter is a simple structured flowmeter, which plays a very important role in the flow measurement of high-temperature liquid metals, especially since the existing flowmeters are difficult to be competent. It has the advantages of easy maintenance and stable operation. Therefore, it is necessary to study the operating conditions of the venturi flowmeter under high-temperature conditions. This work performs a series of simulations of the fluid-solid interaction between the flow liquid metal and venturi flowmeter with COMSOL software, including the dimensional sensitivity analysis of the venturi flowmeter to explore the most suitable structure and parameters for liquid heavy metal, the sensitivity analysis of the geometric parameters of the venturi tube on the varying conditions. It shows that when the contraction angle of the venturi flowmeter is 33°, the diffusion angle is 13°, the diameter of the throat is 8 mm, and the temperature of the lead-bismuth eutectic is 733.15 K, it is most suitable for the measurement in the lead-bismuth circuit.

• Structural Engineering and Mechanics
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• v.91 no.2
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• pp.123-133
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• 2024

The assessment of seismic behavior and seismic performance of ageing Sarıyar concrete gravity dam constructed on Sakarya River in Türkiye is the main focus of this paper. For this purpose, the impact of sediment domain, ageing of concrete material under the impact of chemical and mechanical actions, and dam-water-sediment interaction are included in the two-dimensional (2D) finite element (FE) model developed in FORTRAN 90 environment. In the FE model, the dam and age dependent sediment domains are modeled by solid elements, while reservoir domain is modeled by Lagrangian fluid elements. The radiation of reflected waves to the unbounded water domain is modeled by infinite Lagrangian fluid elements, while unbounded sediment domain is modeled by infinite solid elements. The coupled system was assumed to be under the simultaneous impact of Vertical (V) and Horizontal (H) ingredients of 1976 Koyna earthquake and the coupled system was analyzed in Laplace domain by direct method. Due to the deterioration of the concrete, the H and V displacement responses together with the fundamental period of the body, elongate throughout the lifetime and this reduce the seismic safety of the dam. It was deduced that the ageing dam body will not experience major damages under the Koyna earthquake both at the earlier and later ages. Furthermore, at the heel of the dam, the hydrodynamic pressure responses are decreased by rising the sediment domain depth.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.2
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• pp.133-141
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• 2024

Considering fluid-structure-soil interactions, a finite-element model for a liquid-storage tank is presented and the nonlinear earthquake response analysis is formulated. The tank structure is modeled considering shell elements with geometric and material nonlinearities. The fluid is represented by acoustic elements and combined with the structure using interface elements. To consider the soil-structure interactions, the near- and far-field regions of soil are modeled with solid elements and perfectly matched discrete layers, respectively. This approach is applied to the seismic fragility analysis of a 200,000 kL liquid-storage tank. The fragility curve is observed to be influenced by the amplification and filtering of rock outcrop motions at the site when the soil-structure interactions are considered.

• Journal of Mechanical Science and Technology
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• v.20 no.9
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• pp.1323-1338
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• 2006

An analytical method to estimate the coupled frequencies of the circular plate submerged in fluid is developed using the finite Fourier-Bessel series expansion and Rayleigh-Ritz method. To verify the validity of the analytical method developed, finite element method is used and the frequency comparisons between them are found to be in good agreement. For the perforated plate submerged in fluid, it is almost impossible to develop a finite element model due to the necessity of the fine meshing of the plate and the fluid at the same time. This necessitates the use of solid plate with equivalent material properties. Unfortunately the effective elastic constants suggested by the ASME code are found to be not valid for the modal analysis. Therefore in this study the equivalent material properties of perforated plate are suggested by performing several finite element analyses with respect to the ligament efficiencies.

• Tribology and Lubricants
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• v.14 no.1
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• pp.54-63
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• 1998

In many practical lubricated contacts such as a rough concentrated contact on the sliding of nominally flat surfaces, the fluid may be of molecular (nanometer) scale owing to the asperity interactions on the surfaces. Under this condition, there is insufficient lubricant on the concentrated contact spot to maintain a realistic continuum. Rheological behavior for this kind of concentrated contact has been studied extensively to know whether the application of viscous fluid model is appropriate. The interaction of two rough surfaces is simplified as perfectly flat-rough surfaces contact under certain conditions by "composite topography" and for a nanometer scale fluid film, three kinds of rheological fluid behavior are analyzed in elastohydrodynamic asperity point contact.t contact.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.173-182
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• 1997

In many practical lubricated contacts such as a rough concentrated contact on the sliding of nominally flat surfaces, the fluid may be of molecular (nanometer) scale owing to the asperity interactions on the surfaces. Under this condition, there is insufficient lubricant on the concentrated contact spot to maintain a realistic continuum. Rheological behavior for this kind of concentrated contact was studied to know whether the application of viscous fluid model is appropriate. The interaction of two rough surfaces is simplified as perfectly flat-rough surfaces contact under certain conditions by "composite topography" and for a nanometer scale fluid film, three kinds of rheological fluid behavior are analyzed in elastohydrodynamic asperity point contact.t contact.