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Hydrodynamic And Electrohydrodynamic Instability Of Shear Flows And The Numerical Simulation Of Viscous Droplets, Kenzu Abdella
Hydrodynamic And Electrohydrodynamic Instability Of Shear Flows And The Numerical Simulation Of Viscous Droplets, Kenzu Abdella
Digitized Theses
In this thesis, we investigate three fluid dynamic problems involving various physical mechanisms which exhibit interfacial instability. These problems have wide ranging industrial, scientific and engineering applications.;In the first problem, we investigate the linear stability of the unbounded Couette flow of two fluids separated by a plane interface. The exact dispersion relation is solved asymptotically and numerically to analyze the effects of the four stability parameters of the flow; the ratio of the viscosities, the ratio of the density, the surface tension and gravity. While our results confirm most of the earlier reported theories involving shear flows of fluids of …
Ground Motion Spatial Incoherence, Its Modelling And Effects On Long Gravity Dams, Osman Mohamed Ramadan
Ground Motion Spatial Incoherence, Its Modelling And Effects On Long Gravity Dams, Osman Mohamed Ramadan
Digitized Theses
Seismic design of concrete gravity dams is usually based on a two-dimensional analysis of one monolith, or slice. This analysis provides the basic information but neglects the interaction between adjacent dam monoliths and assumes uniformity of dam section, foundation properties and ground motions along the dam longitudinal axis. While the seismic response of gravity dams has been investigated in considerable detail, the effects of ground motion spatial incoherence on dam response have not been investigated to any great detail.;In this study, dam response to spatially variable seismic excitations is theoretically investigated. Deterministic and random representations of the space-time random field …
Models For Steady State Flow Past A Cylinder, Sergio J. D'Alessio
Models For Steady State Flow Past A Cylinder, Sergio J. D'Alessio
Digitized Theses
Three steady state models for determining the flow of a viscous incompressible Newtonian isothermal fluid past a two-dimensional cylindrical object are proposed. These models offer numerical methods of solving the governing Navier-Stokes equations as well as a mathematical understanding of the nature of the flow.;In the first model, the behaviour of the vorticity is patterned for both large and small distances by expressing the vorticity as {dollar}\zeta\ =\ \Phi\rm e\sp{lcub}\rm F{rcub}{dollar} with F chosen to accommodate both boundary-layer and wake theory. The resulting equations are then solved by finite differences and by the method of Dennis and Chang (1970).;The second …
The Free Vibration Of Plates, Shallow Shells And Solids, Philippe Georges Young
The Free Vibration Of Plates, Shallow Shells And Solids, Philippe Georges Young
Digitized Theses
The Ritz approach is used in this thesis to study the free structural vibration problem of a wide class of plates, shallow shells and solids. The boundaries and/or internal supports of the systems considered are described by polynomials in Cartesian coordinates. The geometric boundary conditions at these boundaries or internal supports are enforced by including in a simple polynomial trial series the polynomial equation describing the position of the support raised to the appropriate power. For plates and shallow shells, in some instances, the displacement field is discretized into several domains or elements, as in the standard finite element method, …
Multibond Graph Method For Flexible Multibody System Dynamics, Simon Xun-Nan He
Multibond Graph Method For Flexible Multibody System Dynamics, Simon Xun-Nan He
Digitized Theses
In this thesis, a general method for the modelling and simulation of the dynamics of flexible multibody systems undergoing special motion is developed using the multiband graph approach. Until now, bond graph was mostly used to model rigid multibody system dynamics and two dimensional flexible bodies. The multibond graph approach developed in this thesis for the computer-aided modelling and simulation of flexible multibody system dynamics provides an alternative to current computer-aided modelling and simulation of 3-D flexible multibody system dynamics with the added advantage of including a mixed energy domain. The flexible multibody system considered consists of a number of …
Response Statistics Of Shell Structures With Geometrical And Material Nonlinearities, Meilan Liu
Response Statistics Of Shell Structures With Geometrical And Material Nonlinearities, Meilan Liu
Digitized Theses
The investigation in this thesis is concerned with response statistics of shell structures with geometrical and material nonlinearities under stationary and non-stationary Gaussian random excitations.;A series of hybrid strain based three node flat triangular shell elements is developed for linear and nonlinear shell structural analyses. In the former the Hellinger-Reissner variational principle is employed. The elements are obtained by combining a triangular bending element and a plane stress element, and incorporating the drilling degrees-of-freedom. For the nonlinear analysis the updated Lagrangian formulation and the incremental Hellinger-Reissner variational principle are applied, with incremental displacements and strains being the independently assumed fields. …