Thesis (M.S.)--Ohio State University, 2005. / Includes bibliographical references (leaves 166-170). Available online via OhioLINK's ETD Center

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Egerstedt, Magnus; Committee Co-Chair: Wardi, Yorai; Committee Member: Riley, George; Committee Member: Taylor, David; Committee Member: Tovey, Craig; Committee Member: Yezzi, Anthony. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Dissertation (Ph.D.)--University of Toledo, 2005. / Typescript. "A dissertation [submitted] as partial fulfillment of the requirements of the Doctor of Philosophy degree in Engineering." Bibliography: leaves 61-63.

Thesis (M.S.)--Tennessee Technological University, 2009. / Title from title page screen (viewed on June 29, 2010). Bibliography: leaves 127-131.

Thesis (doctoral)--Lund University, 1992. / Added t.p. with thesis statement inserted.

Zugl.: Braunschweig, Techn. Univ., Diss., 2009

Universiẗat, Diss., 2005--Freiburg (Breisgau). / Erscheinungsjahr an der Haupttitelstelle: 2004.

Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request

In hybrid RANS/LES, Reynolds-averaged Navier-Stokes (RANS) equations method is used to treat the near-wall region and large-eddy simulation (LES) is applied to the core turbulent region. Owing to the incompatibility of these two numerical modelling approaches, an artificial (i.e., non-physical) buffer layer forms along the interface where the model switches from RANS to LES. In this thesis, a novel dynamic forcing scheme incorporating backscatter is proposed in order to remove the artificial buffer layer. In contrast to previous forcing techniques, the proposed forcing is determined dynamically from the flow field itself, and does not require any extraction of turbulent fields from reference direct numerical simulation (DNS) or high-resolution LES databases. The proposed forcing model has been tested on three types of wall-bounded turbulent flows, namely, turbulent flow in a plane channel; turbulent flow in a spanwise rotating channel; and turbulent flow in a spanwise rotating rib-roughened channel. In order to validate the present hybrid approach, turbulence statistics obtained from hybrid RANS/LES simulations are thoroughly compared with the available DNS results and laboratory measurement data. Based on the study of a plane channel flow, transport equations for the resolved turbulent stresses and kinetic energy are introduced to investigate the effects of dynamic forcing on reduction of the thickness and impact of the artificial buffer layer. As long as the dynamic forcing is in use, the artificial buffer layer have been successfully removed, indicating that the proposed hybrid approach is insensitive to the choices of the forcing region or interface location. The predictive performance of the dynamic forcing scheme has been further evaluated by considering turbulent flows subjected to a special type of body force, i.e., the non-inertial and non-conservative Coriolis force. Due to the effects of system rotation, turbulence level is enhanced on the pressure side and suppressed on the suction side of the rotating channel. Furthermore, it is reported in this thesis that the classification of the roughness type now relies not only on the pitch ratio, but also on the rotation number in the context of rotating rib-roughened flows. / February 2016

Miniature Hybrid Microwave Integrated Circuits (MHMIC's) in conjunction with Monolithic MIC's (MMIC's) play an important role in modern telecommunication systems. Accurate, fast and reliable analysis tools are crucial to the design of MMIC's and MHMIC's. The space-spectral domain approach (SSDA) is such a numerically efficient method, which combines the advantage of the one-dimensional method of lines (MoL) with that of the one-dimensional spectral-domain method (SDM). In this dissertation, the basic idea of the SSDA is first introduced systematically. Then, a quasi-static deterministic variation of the SSDA is developed to analyze and design low dispersive 3-D MMIC's and MHMIC's. S-parameters and equivalent circuit elements for discontinuities are investigated. This includes air bridges, smooth transitions, open ends, step in width and gaps in coplanar waveguide (CPW) or microstrip type circuits. Experimental work is done to verify the simulation. The full-wave SSDA is a more generalized and field theoretically exact numerical tool to model also dispersive circuits. The new concept of self-consistent hybrid boundary conditions to replace the modal source concept in the feed line is used here. In parallel, a deterministic approach is developed. Scattering parameters for some multilayered planar discontinuities including dispersion effect are calculated to validate this method. / Graduate