Civil Engineering / İnşaat Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/13

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End date: 1999Publisher: search.filters.publisher.John Wiley and Sons Inc.

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  • Conference Object
    A Boundary Element Method for Axisymmetric Elastodynamic Analysis
    (John Wiley and Sons Inc., 1996) Özkan, Gonca; Mengi, Yalçın
    A new numerical method is proposed for the boundary element analysis of axisymmetric bodies. The method is based on complex Fourier series expansion of boundary quantities in circumferential direction, which reduced the boundary element equation to an integral equation in (r-z) plane involving the Fourier coefficients of boundary quantities, where r and z are the coordinates of the r theta z cylindrical coordinate system. The kernels appearing in these integral equations can be computed effectively by discrete Fourier transform formulas together with the fast Fourier transform (FFT) algorithm, and the integral equations (r-z) plane can be solved by Gaussian quadrature, which establishes the Fourier coefficients associated with boundary quantities. The Fourier transform solution can then be inverted into r theta z space by using again discrete Fourier transform formulas together with FFT algorithm. In this paper, we present the formulation of the proposed method which is outlined above. A comparison is given between the existent methods in literature and our method, which shows that the use of FFT algorithm for the integrations in circumferential direction provides considerable saving in computer time.
  • Article
    Citation - WoS: 12
    Citation - Scopus: 12
    Oil Mound Spreading and Migration With Ambient Groundwater Flow in Coarse Porous Media
    (John Wiley and Sons Inc., 1996) Çorapçıoplu, M. Yavuz; Tuncay, Kağan; Ceylan, B. Kağan
    When a light, immiscible oil leaks above an unconfined aquifer, it spreads and forms a floating mound on the table. The oil mound migrates in the direction of ambient ground flow. In this study we present a governing equation for the migrating mound thickness by averaging the oil phase mass balance equation. Analytical and numerical solutions to an advective- dispersive type equation are presented to estimate the temporal and spatial distribution of the migrating oil mound thickness for two problems of practical importance: formation, spreading, and migration of an oil mound on the table and spreading and migration of an established layer of oil with ambient ground flow. The model results compare favorably with test data obtained by laboratory flume experiments. Although the model has some simplifying assumptions such as the absence of capillary pressure gradients, sharp saturation changes across the phase interfaces, and single mobile phase (i.e., oil flow only), it can be useful as a screening or site assessment tool because of its relative simplicity.
  • Article
    Citation - WoS: 75
    Citation - Scopus: 82
    Body Waves in Poroelastic Media Saturated by Two Immiscible Fluids
    (John Wiley and Sons Inc., 1996) Tuncay, Kağan; Çorapçıoğlu, M. Yavuz
    A study of body waves in elastic porous media saturated by two immiscible Newtonian fluids is presented. We analytically show the existence of three compressional waves and one rotational wave in an infinite porous medium. The first and second compressional waves are analogous to the fast and slow compressional waves in Biot's theory. The third compressional wave is associated with the pressure difference between the fluid phases and dependent on the slope of capillary pressure-saturation relation. Effect of a second fluid phase on the fast and slow waves is numerically investigated for Massillon sandstone saturated by air and water phases. A peak in the attenuation of the first and second compressional waves is observed at high water saturations. Both the first and second compressional waves exhibit a drop in the phase velocity in the presence of air. The results are compared with the experimental data available in the literature. Although the phase velocity of the first compressional and rotational waves are well predicted by the theory, there is a discrepancy between the experimental and theoretical values of attenuation coefficients. The causes of discrepancy are explained based on experimental observations of other researchers.