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Full-Text Articles in Mechanical Engineering

A Delayed Detached Eddy Simulation Model With Low Reynolds Number Correction For Transitional Swirling Flow In A Multi-Inlet Vortex Nanoprecipitation Reactor, Zhenping Liu, James C. Hill, Rodney O. Fox, Alberto Passalacqua, Michael G. Olsen Aug 2018

A Delayed Detached Eddy Simulation Model With Low Reynolds Number Correction For Transitional Swirling Flow In A Multi-Inlet Vortex Nanoprecipitation Reactor, Zhenping Liu, James C. Hill, Rodney O. Fox, Alberto Passalacqua, Michael G. Olsen

Chemical and Biological Engineering Publications

The objective of the presented work is to verify a delayed detached eddy simulation (DDES) model for simulating transitional swirling flow in a micro-scale multi-inlet vortex reactor (MIVR). The DDES model is a k-w based turbulence model with a low Reynolds number correction applied to the standard k-w model such that the Reynolds-averaged Navier-Stokes (RANS) component of the DDES model is able to account for low Reynolds number flow. By limiting the dissipation rate in the k-equation, the large-eddy simulation (LES) part of the DDES model behaves similarly to a one-equation sub-grid model. The turbulent Reynolds number is redefined to ...


Computational Study Of Desalination By Membranes, Mustafa Usta Aug 2018

Computational Study Of Desalination By Membranes, Mustafa Usta

Theses and Dissertations

Water desalination by membranes constitutes the majority of the low-quality water purication systems that extends across many different techniques. This study considers transport phenomena in reverse osmosis (RO) and vacuum membrane distillation (VMD) modules using computational techniques. Reverse osmosis is a pressure-driven separation method using semi-permeable membranes featuring nanoporous structures. Vacuum membrane distillation is another emerging separation method relying on the temperature difference across the microporous hydrophobic membranes.The membrane separation process intrinsically gives rise to temperature polarization (TP) and concentration polarization (CP) which could be severe limitations in these systems. To eliminate these polarizations and increase the module performance ...


High-Fidelity Multidisciplinary Design Optimization Of A 3d Composite Material Hydrofoil, Silvia Volpi May 2018

High-Fidelity Multidisciplinary Design Optimization Of A 3d Composite Material Hydrofoil, Silvia Volpi

Theses and Dissertations

Multidisciplinary design optimization (MDO) refers to the process of designing systems characterized by the interaction of multiple interconnected disciplines. High-fidelity MDO usually requires large computational resources due to the computational cost of achieving multidisciplinary consistent solutions by coupling high-fidelity physics-based solvers. Gradient-based minimization algorithms are generally applied to find local minima, due to their efficiency in solving problems with a large number of design variables. This represents a limitation to performing global MDO and integrating black-box type analysis tools, usually not providing gradient information. The latter issues generally inhibit a wide use of MDO in complex industrial applications.

An architecture ...


Simplified, Alternative Formulation Of Numerical Simulation Of Proton Exchange Membrane Fuel Cell, Russell L. Edwards Apr 2018

Simplified, Alternative Formulation Of Numerical Simulation Of Proton Exchange Membrane Fuel Cell, Russell L. Edwards

Mechanical & Aerospace Engineering Theses & Dissertations

Three-Dimensional proton exchange fuel cell (PEMFC) operation in steady-state is simulated with computational fluid dynamics / multiphysics software that is based upon the finite-element method. PEMFC operation involves the simultaneous simulation of multiple, interconnected physics involving fluid flows, heat transport, electrochemical reactions, and both protonic and electronic conduction. Modeling efforts have varied by how they treat the physics occurring within and adjacent to the membrane-electrode assembly (MEA). Several approaches treat the MEA as part of the computational domain, solving multiple, and coupled conservation equations via the CFD approach within the 3 regions of the MEA. The thickness dimensions of the 3 ...


Computational Investigation Using Bleed As A Method Of Shock Stabilization, Dayle L. Chang Mar 2018

Computational Investigation Using Bleed As A Method Of Shock Stabilization, Dayle L. Chang

Theses and Dissertations

Shock-wave/boundary layer interactions (SWBLI) produce undesirable dynamic loads and separated unsteady flows, adversely impacting the performance and structural integrity of supersonic vehicles. Computational fluid dynamics (CFD) is a successful tool in experimental planning and shows promise as a critical tool in understanding and mitigating negative effects of SWBLI. The goal of this research is to demonstrate the effect of bleed holes on shock stability using the OVERFLOW CFD solver to inform the planning of an Air Force Research Laboratory (AFRL) SWBLI wind tunnel experiment. First, a two-dimensional, flat plate, single-hole configuration was developed. Massflow discrepancies of 14.8% were ...


Uncertainty In Combustion Reaction Rates And Its Effects On Combustion Simulations, Joshua Piehl Jan 2018

Uncertainty In Combustion Reaction Rates And Its Effects On Combustion Simulations, Joshua Piehl

Wayne State University Theses

This work investigates the uncertainties in reaction rates of an n-dodecane model on turbulent spray combustion simulations. Six major reactions were found to significantly impact the ignition delay of the mechanism in a 0-D batch reactor model. These reactions’ rates were independently modified and placed into individual mechanisms. These newly developed mechanisms were simulated in a 3-D turbulent spray simulation and a 0-D batch reactor at a pressure of 60 bar and temperatures from 900 to 1100 K. The combustion characteristics (e.g. ignition delays, flame lift-off length, liquid and vapor penetration) of the modified mechanisms were compared to those ...


Electric-Field Assisted Manipulation And Self-Assembly Of Particle Suspensions, Edison Chijioke Amah Jan 2018

Electric-Field Assisted Manipulation And Self-Assembly Of Particle Suspensions, Edison Chijioke Amah

Dissertations

No abstract provided.


Design Of A Novel Tissue Culture System To Subject Aortic Tissue To Multidirectional Bicuspid Aortic Valve Wall Shear Stress, Janet Liu Jan 2018

Design Of A Novel Tissue Culture System To Subject Aortic Tissue To Multidirectional Bicuspid Aortic Valve Wall Shear Stress, Janet Liu

Browse all Theses and Dissertations

Blood vessels experience complex hemodynamics marked by three-dimensionality and pulsatility. Arterial endothelial cells interact with the characteristics of the fluid wall shear stress (WSS) to maintain homeostasis or promote disease states. In particular, the bicuspid aortic valve (BAV), a congenital heart valve anatomy consisting of two leaflets instead of three, is associated with aortic complications presumably promoted by hemodynamic abnormalities. While devices have been used to test this hypothesis, their capabilities are limited to the generation of time-varying WSS magnitude in one direction. However, the increased flow helicity generated by BAVs in the aorta is expected to result in increased ...


Dust Control Examination Using Computational Fluid Dynamics Modeling And Laboratory Testing Of Vortecone And Impingement Screen Filters, Ashish R. Kumar Jan 2018

Dust Control Examination Using Computational Fluid Dynamics Modeling And Laboratory Testing Of Vortecone And Impingement Screen Filters, Ashish R. Kumar

Theses and Dissertations--Mining Engineering

Heavy industries, such as mining, generate dust in quantities that present an occupational health hazard. Prolonged exposure to the respirable dust has been found to result in many irreversible occupational ailments in thousands of miners. In underground mining applications, a variety of scrubbing systems are used to remove dust near the zones of generation. However, the wire-mesh type fibrous screens in the flooded-bed dust scrubbers used on continuous miners, are prone to clogging due to the accumulation of dust particles. This clogging results in a reduced capture efficiency and a higher exposure to the personnel. This research establishes the Vortecone ...


Erosion Degradation Characteristics Of A Linear Electro-Hydrostatic Actuator Under A High-Frequency Turbulent Flow Field, Yuan Li, Shaoping Wang, Mileta M. Tomovic, Chao Zhang Jan 2018

Erosion Degradation Characteristics Of A Linear Electro-Hydrostatic Actuator Under A High-Frequency Turbulent Flow Field, Yuan Li, Shaoping Wang, Mileta M. Tomovic, Chao Zhang

Engineering Technology Faculty Publications

The paper proposes a performance degradation analysis model based on dynamic erosion wear for a novel Linear Electro-Hydrostatic Actuator (LEHA). Rather than the traditional statistical methods based on degradation data, the method proposed in this paper firstly analyzes the dominant progressive failure mode of the LEHA based on the working principle and working conditions of the LEHA. The Computational Fluid Dynamics (CFD) method, combining the turbulent theory and the micro erosion principle, is used to establish an erosion model of the rectification mechanism. The erosion rates for different port openings, under a time-varying flow field, are obtained. The piecewise linearization ...


Optimization Of Microfluidic Particle Separator Geometry Using Computational Fluid Dynamics, Joseph Petersen Jan 2018

Optimization Of Microfluidic Particle Separator Geometry Using Computational Fluid Dynamics, Joseph Petersen

Electronic Theses and Dissertations

Computational fluid dynamics software was used to simulate the motion of circulating tumor cells in a variety of microfluidic cell isolation devices. Design of several novel microfluidic cell isolation devices was aided by viewing streamlines of fluid in devices in simulation. Devices that performed best in simulation used 5-micrometer wide guiding channels to guide cells to the capture location in the device. While these devices performed better than other devices in simulation and captured all particles regardless of position along inlet, experimental results differ from simulation.