Dynamics of submerged shells of arbitrary geometry using improved transmitting boundaries

Akkas, N
Tuncay, Kağan
The dynamics of shells of arbitrary geometry submerged in an acoustic medium has attracted attention for many decades. Only a finite region of the finite fluid domain can be modelled in the numerical analysis. The artificial surface encompassing the finite region is called the truncation surface, on which the transmitting boundary condition is used. The classical plane wave, cylindrical wave and spherical wave approximations are the first generation approximations. The residual variable method has made it possible to develop second generation improved transmitting boundary conditions in Cartesian, cylindrical and spherical coordinates. A general purpose finite element program, in which both the classical and improved transmitting boundary conditions have been incorporated, has been coded and verified. The response of a point excited submerged ellipsoidal shell is studied. The ellipsoidal shell is enclosed in a spherical truncation surface. The numerical results on the apex deflection are presented and they are compared with that of the spherical shell. (C) 1997 Civil-Comp Ltd and Elsevier Science Ltd.


Surface response of a viscoelastic medium to subsurface acoustic sources with application to medical diagnosis
Royston, Thomas J.; Yazıcıoğlu, Yiğit; Loth, Francis (Acoustical Society of America (ASA), 2003-02-01)
The response at the surface of an isotropic viscoelastic medium to buried fundamental acoustic sources is, studied theoretically, computationally and experimentally. Finite and infinitesimal monopole and. dipole sources within the low audible frequency range (40-400 Hz) are considered. Analytical and numerical integral solutions that account for compression, shear and surface wave response to the, buried sources are formulated and compared with numerical finite element simulations and, experimental studies ...
Characteristics of free overfall for supercritical flows
Tokyay, Nuray (2007-02-01)
The characteristics of supercritical flow at a vertical drop in a rectangular channel are studied experimentally to obtain information that would be valuable to designers of hydraulic structures. The relationship between the ratio of brink depth to the depth of upstrearn supercritical flow (i.e., end-depth ratio) and the Froude number is determined. Downstream from the vertical drop, the physical characteristics of the failing jet are examined, such as the height of the standing water behind the jet, the ma...
Design and realization of a high voltage radio interference voltage (riv) measurement system
Özer, Mutlu; Hızal, Mirzahan; Department of Electrical and Electronics Engineering (2010)
This thesis aims the design and the realization of a radio noise meter which can be used to measure radio interference of a high-voltage transmission line due to partial discharges like conductor corona. The radio noise meter is the common equipment for radio noise and radio interference voltage measurements. The corona of transmission lines, its characteristics, its effects on radio interference and measurement of corona caused radio noise in the scope of relevant international standards are investigated. ...
Near-field scanning in the time domain on a spherical surface - A formulation using the free-space Green's function
Koc, S; Aydın Çivi, Hatice Özlem; Buyukdura, OM (2001-10-01)
Two formulations for determining the characteristics of an unknown source of acoustic waves using the measurement of its field at its near zone are presented. The measurement in both cases is to be performed on a spherical scan surface which encapsulates the source. The first is for an ideal probe which measures the field at its location. The knowledge of the field is sufficient; its normal derivative is not required. In the second formulation a realistic probe is considered. This time it is required only t...
Elastic waveform inversion using Gauss-Newton method
Sheen, Dong-hoon; Baag, Chang-eob; Tuncay, Kağan; Ortoleva, Peter J. (2005-01-01)
Seismic waveform inversion has been solved usually by a gradient type approach for acoustic media. In this paper, we present an elastic waveform inversion method based on the Gauss‐Newton method. Elastic wave propagation simulation and inversion are both implemented in the time domain. The partial derivative wavefields are computed explicitly using convolutions of forward and reciprocal wavefields. Numerical experiments show that the Gauss‐Newton elastic waveform inversion significantly improves of resolvin...
Citation Formats
N. Akkas and K. Tuncay, “Dynamics of submerged shells of arbitrary geometry using improved transmitting boundaries,” COMPUTERS & STRUCTURES, pp. 827–835, 1997, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/38215.