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Theses/Dissertations

Chemical engineering

Retrospective Theses and Dissertations

Physics

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Full-Text Articles in Engineering

Theoretical And Experimental Explorations In Atomic Force Microscopy , Anil Gannepalli Jan 2004

Theoretical And Experimental Explorations In Atomic Force Microscopy , Anil Gannepalli

Retrospective Theses and Dissertations

Nanotechnology is the capability to build by controlling the arrangement of individual atoms and molecules. Such a technology would be founded on the ability to control, manipulate and investigate matter at the atomic scale. The invention of atomic force microscope (AFM) and the advances in micro-cantilever based scanning probe technology have significantly enhanced the experimental capability to probe and modify matter at the nanoscale. However, it is still severely limited in achieving the necessary bandwidth, sensitivity and resolution. To further the advances in this field an in-depth understanding of the nature and effects of the tip-sample interactions is imperative. A ...


Hybrid Finite-Volume/Transported Pdf Method For The Simulation Of Turbulent Reactive Flows , Venkatramanan Raman Jan 2003

Hybrid Finite-Volume/Transported Pdf Method For The Simulation Of Turbulent Reactive Flows , Venkatramanan Raman

Retrospective Theses and Dissertations

A novel computational scheme is formulated for simulating turbulent reactive flows in complex geometries with detailed chemical kinetics. A Probability Density Function (PDF) based method that handles the scalar transport equation is coupled with an existing Finite Volume (FV) Reynolds-Averaged Navier-Stokes (RANS) flow solver. The PDF formulation leads to closed chemical source terms and facilitates the use of detailed chemical mechanisms without approximations. The particle-based PDF scheme is modified to handle complex geometries and grid structures. Grid-independent particle evolution schemes that scale linearly with the problem size are implemented in the Monte-Carlo PDF solver. A novel algorithm, in situ adaptive ...


Sonochemical Reactions: Mass Transfer And Kinetic Studies Of A Solid-Liquid System , Leigh Christine Hagenson Jan 1997

Sonochemical Reactions: Mass Transfer And Kinetic Studies Of A Solid-Liquid System , Leigh Christine Hagenson

Retrospective Theses and Dissertations

Ultrasound has been shown to have desirable effects on both homogeneous and heterogeneous reactions, such as increasing the conversion, enhancing the selectivity, and improving the yield. Enhancements due to ultrasound may be attributed to chemical effects or mechanical effects, or to both simultaneously. The chemical effects of ultrasound are attributed to the implosion of microbubbles, generating free-radicals with a great propensity for reaction. Mechanical effects are caused by shock waves formed during symmetric cavitation, or by microjets formed when the bubble implodes asymmetrically. Research emphasis in this area attempts to discern the mechanisms behind ultrasound's mechanical effects by selecting ...


Turbulent Scalar Transport Using Two-Point Statistical Closure Theory , Robert Charles Sanderson Jan 1995

Turbulent Scalar Transport Using Two-Point Statistical Closure Theory , Robert Charles Sanderson

Retrospective Theses and Dissertations

The turbulent transport of a passive scalar (Corrsin's problem with diffusion) and of an active scalar in stably stratified fluids is studied using linear analysis (rapid distortion theory or RDT), Kraichnan's direct interaction approximation (DIA) and direct numerical simulation (DNS). The results are compared with each other and with laboratory experiments. The numerical results compare favorably with the experiments of Sirivat and Warhaft, Budwig, Tavoularis and Corrsin and Stillinger and Itsweire of van Atta's group. The RDT study reveals that much of the qualitative behavior observed in experiments, such as the tendency for the system to evolve ...