Thesis (Ph.D. 1973) from the Dept. of Electrical Engineering, University of Adelaide. / 3 offprints in back pocket.

Thesis (Ph.D.) -- University of Adelaide, Dept. of Mechanical Engineering, 2000? / Bibliography: leaves 153-156.

Thesis (Ph.D.)--University of Adelaide, Dept. of Mechanical Engineering, 2000. / Title from screen page (viewed September 13 2005). Includes bibliographical references. Also available in print version.

Thesis (P.H.D.)--Johns Hopkins University, 1912. / Biographical sketch. "Reprinted from the Physical review, vol. xxv., no. 5, Nov. 1912."

Inaug.--diss.--Rostock.

M.Ing. (Mechanical Engineering) / An experimental investigation has been carried out to study the influence of sound waves on the transition from laminar to turbulent flow in the boundary layer associated with natural convection from a vertical flat plate with uniform surface heat flux. A relationship exists between frequency and Grashof number at transition. Buckling flow theory provides a means of explaining this relationship. Numerical solutions for the temperature and velocity distributions in an enclosed cavity with one heated vertical wall have been obtained. The frequency of applied sound waves at which transition in the boundary layer would occur, is predicted.

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No description available.

The current work is devoted to the problem of sound wave scattering by elastic cylindrical objects in a plain acoustic waveguide. The Multi- Modal Integral Method (MMIM) is proposed, which is based on nonstandard representation of the Green's function. It combines advantages of integral equation and eigenfunction methods and provides a quickly converging and highly accurate solution, taking into account all the waveguide modes up to infinite order. As illustrations of application of this method, acoustic diffraction is calculated from a system of several parallel homogeneous cylinders and from an air-filled cylindrical elastic shell. Numerical solutions are found for various versions of the system of elastic cylinders in a fluid layer with perfectly soft and rigid boundaries. Phase - frequency and amplitude - frequency characteristics are found for modal coefficients of the scattered field. Sharp increase of their amplitudes is found near resonance frequencies of the waveguide and the scattering cylinders. Pictures of the source density on the surface of the cylinders show that the nature of their distribution strongly depends on the frequency and the mutual location of the cylinders in the waveguide. Field structure near the cylinders reveals that higher-order waveguide modes play a significant role in the scattering process. Spatial distribution of the acoustic power flow near the scattering object is calculated for several frequencies and two sets of elastic properties of the cylinder. It is shown that at the critical frequencies of the waveguide as well as at the internal resonances of the cylinder the acoustic energy flows in closed paths in some regions of the waveguide. Near the internal resonances of the cylinder the closed paths are located in the near vicinity of the scattering object and partially go through its interior. It is suggested that re-radiation of the energy stored in the vortices may contribute to the echo phenomenon. The integral reflection coefficient is calculated for a system waveguide/shell for different values of wall thickness and distance between the shell and the waveguide bottom. Maxima and minima in the reflection coefficient associated with cut-on frequencies of the waveguide modes and structural resonances of the shell are identified. The calculations show that the conventional definition of target strength in a shallow waveguide is inappropriate. Different kinds of resonances are identified in frequency and angular dependencies of the velocity amplitude of the shell surface. These resonances belong to the following groups: a) critical frequencies of the waveguide modes, b) structural resonances of the elastic shell, c) resonance oscillations of the gas-filled interior of the shell, d) resonance oscillations of the coupled fluid-shell. Application of the Multi-Modal Integral Method (MMIM) to Sound Wave Scattering in an Acoustic Waveguide. Temporal sequences of pictures showing the spatial structure of the total and scattered fields in the near and far field zones are obtained. It is shown that the incident field produces waves of acoustic pressure propagating along the boundary of the scattering object, which, in turn, generate the scattered acoustic field. In the process of propagation, the waves may interact with each other via the fluid or the scattering object. This leads to significant changes of the structure of the acoustic field and of the amount of acoustic energy reflected from the scatterer. It is also shown that, in most cases, standing waves exist between the scatterer and the waveguide boundaries. Accuracy of the Multi-Modal Integral Method is discussed. It is shown that the implementation of the method requires few computer resources for good accuracy of the solution. / Thesis (Ph.D.)--School of Mechanical Engineering, 1999.

No description available.