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Full-Text Articles in Mechanical Engineering

Efficient Adjacency Queries And Dynamic Refinement For Meshfree Methods With Applications To Explicit Fracture Modeling, James Olliff Jun 2018

Efficient Adjacency Queries And Dynamic Refinement For Meshfree Methods With Applications To Explicit Fracture Modeling, James Olliff

Graduate Theses and Dissertations

Meshfree methods provide a more practical approach to solving problems involving large deformation and modeling fracture compared to the Finite Element Method (FEM). However meshfree methods are more computationally intensive compared to FEM, which can limit their practicality in engineering. Meshfree methods also lack a clear boundary definition, restricting available visualization techniques. Determining particle locations and attributes such that a consistent approximation is ensured can be challenging in meshfree methods, especially when employing h-refinement. The primary objective of this work is to address the limitations associated with computational efficiency, meshfree domain discretization, and h-refinement, including both placement of particles as ...


Dns And Les Of Scalar Transfer Across An Air-Water Interface During Inception And Growth Of Langmuir Circulation, Amine Hafsi Nov 2017

Dns And Les Of Scalar Transfer Across An Air-Water Interface During Inception And Growth Of Langmuir Circulation, Amine Hafsi

Graduate Theses and Dissertations

Direct numerical simulations (DNS) of an initially quiescent coupled air-water interface driven by an air flow with free stream speed of 5 m/s have been conducted. The DNS solves a scalar advection-diffusion equation for dissolved gas (or scalar) concentration in order to determine the impact of the water-side turbulence on scalar (mass) transfer from the air side to the water side and subsequent vertical transport in the water column. Two simulations are compared: one with a freely deforming interface and a second one with a flat interface. In the first simulation, the deforming interface evolves in the form of ...


Corrosion Of Steel In Submerged Concrete Structures, Michael Thomas Walsh Nov 2015

Corrosion Of Steel In Submerged Concrete Structures, Michael Thomas Walsh

Graduate Theses and Dissertations

This investigation determined that severe corrosion of steel can occur in the submerged portions of reinforced concrete structures in marine environments. Field studies of decommissioned pilings from actual bridges revealed multiple instances of strong corrosion localization, showing appreciable local loss of steel cross-section. Quantitative understanding of the phenomenon and its causes was developed and articulated in the form of a predictive model. The predictive model output was consistent with both the corrosion rate estimates and the extent of corrosion localization observed in the field observations. The most likely explanation for the observed phenomena that emerged from the understanding and modeling ...


Numerical Simulation Of Flow In Ozonation Process, Jie Zhang May 2014

Numerical Simulation Of Flow In Ozonation Process, Jie Zhang

Graduate Theses and Dissertations

In the last two decades, Computational Fluid Dynamics (CFD) has shown great potential as a powerful and cost-efficient tool to troubleshoot existing disinfection contactors and improve future designs for the water and wastewater treatment utilities.

In the first part of this dissertation two CFD simulation methodologies or strategies for computing turbulent flow are evaluated in terms of the predicted hydraulic performance of contactors. In the LES (large eddy simulation) methodology, the more energetic, larger scales of the turbulence are explicitly computed or resolved by the grid. In the less computationally intensive RANS (Reynolds-averaged Navier-Stokes) methodology, only the mean component of ...


Environmental And Energy Saving Technologies Of Vinyl Chloride Production, Mykola Kurta Feb 2013

Environmental And Energy Saving Technologies Of Vinyl Chloride Production, Mykola Kurta

Graduate Theses and Dissertations

Recently, because of the increase of environmental concerns in process design, the need to enhance conversion to product and prevent generation of wasteful byproducts in the reactor network has become urgent. This prevents high cost treatment and separation costs downstream in the process. Therefore, in this thesis I focus on making production of vinyl chloride monomer (VCM) more efficient and on possible ways of industrial organochlorine waste (OCW) recycling. In particular, in the first experiment, we investigate how catalyst and its structure can affect product output.

Infrared spectroscopy and X-ray diffraction analysis were utilized to investigate the structure of the ...


Towards Rans Parameterization Of Vertical Mixing By Langmuir Turbulence In Shallow Coastal Shelves, Nityanand Sinha Jan 2013

Towards Rans Parameterization Of Vertical Mixing By Langmuir Turbulence In Shallow Coastal Shelves, Nityanand Sinha

Graduate Theses and Dissertations

Langmuir turbulence in the upper ocean is generated by the interaction between the wind-driven shear current and the Stokes drift velocity induced by surface gravity waves. In homogenous (neutrally stratified) shallow water, the largest scales of Langmuir turbulence are characterized by full-depth Langmuir circulation (LC). LC consists of parallel counter-rotating vortices aligned roughly in the direction of the wind. In shallow coastal shelves, LC has been observed engulfing the entire water column, interacting with the boundary layer and serving as an important mechanism for sediment re-suspension.

In this research, large-eddy simulations (LES) of Langmuir turbulence with full-depth LC in a ...


Minimal And Symmetric Global Partition Polynomials For Reproducing Kernel Elements, Mario Jesus Juha Jan 2011

Minimal And Symmetric Global Partition Polynomials For Reproducing Kernel Elements, Mario Jesus Juha

Graduate Theses and Dissertations

The Reproducing Kernel Element Method is a numerical technique that combines finite element and meshless methods to construct shape functions of arbitrary order and continuity, yet retains the Kronecker-d property. Central to constructing these shape functions is the construction of global partition polynomials on an element. This dissertation shows that asymmetric interpolations may arise due to such things as changes in the local to global

node numbering and that may adversely affect the interpolation capability of the method. This issue arises due to the use in previous formulations of incomplete polynomials that are subsequently non-affine invariant. This dissertation lays out ...


Physically Meaningful Harmonization Of Tire/Pavement Friction Measurement Devices, Madhura Priyanga Nishshanke Rajapakshe Jan 2011

Physically Meaningful Harmonization Of Tire/Pavement Friction Measurement Devices, Madhura Priyanga Nishshanke Rajapakshe

Graduate Theses and Dissertations

Accurate characterization and evaluation of tire/pavement friction is critical in assuring runway and highway safety. Historically, Pavement Friction Measurement Devices (PFMDs) employing different measuring mechanisms have been used to evaluate tire/pavement friction. They yield significantly disparate friction coefficients under the same contact conditions. Currently, an empirically developed data harmonization method based on a reference device (Dynamic Friction Tester (DFT)) is used in an attempt to overcome the disparities between the measurements using various different PFMDs. However, this method, which has been standardized by the American Society for Testing and Materials (ASTM E1960), has been criticized for its inconsistency ...