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Numerical Study Of Owls’ Leading-Edge Serrations, Asif Shahriar Nafi

Electronic Theses and Dissertations

The silent flight ability of owls is often attributed to their unique wing morphology and its interaction with their wingbeat kinematics. Among these distinctive morphological features, leading-edge serrations stand out – these are rigid, miniature, hook-like patterns located at the leading edge of the primary feathers of their wings. It had been hypothesized that these leading-edge serrations serve as a passive flow control mechanism, influencing the aerodynamic performance and potentially affecting the boundary layer development over the wing, subsequently influencing wake flow dynamics. Despite being the subject of research spanning multiple decades, a consensus regarding the aerodynamic mechanisms underpinning owls’ …

Modeling Of Transport In Anatomic Respiratory Airways: Applications In Targeted Drug Delivery And Airborne Pathogenic Transmissions, Mohammad Mehedi Hasan Akash

Electronic Theses and Dissertations

This thesis aims to explore the potential of improving the efficacy of drugs for treatment of viral infections by targeting the nasopharynx, which is commonly the first site of infection for many viral pathogens. Currently, intranasal sprays are used, but the standard protocol (“Current Use” or CU) results in suboptimal drug deposition at the nasopharynx. To address this issue, an “Improved Use” or, IU protocol has been proposed, which involves pointing the spray bottle at a shallower angle and aiming slightly towards the cheeks. The IU delivery is also robust to perturbations in spray direction, which highlights the practical utility …

On The Simulation Of Supersonic Flame Holder Cavities With Openfoam, Zachary Chapman

Electronic Theses and Dissertations

One of the next major advancements in the aerospace industry will be hypersonic flight. However, to achieve hypersonic flight, propulsion systems capable of reaching hypersonic speeds need to be developed. One of the more promising hypersonic propulsion systems is the scramjet engine, however, several problems still need to be explored before reliable scramjet engines can be produced, the biggest being keeping the engine ignited. This has led to the use of flame holder cavities to create a region of subsonic flow within the engine to allow combustion to occur. High experimental costs make the use of computational fluid dynamic (CFD) …

Predictive Model Of Air Dam Deflection Under Aerodynamic Loads, Chang Kyun Kang

Electronic Theses and Dissertations

Plastic components are widely used on the exterior body of automotive vehicles. When the vehicle is moving, these components experience deformation caused by air flow. Simultaneously, the deformation affects the flow of air around the vehicle. This research is focused on developing virtual simulation techniques for determining the vehicle air dam behaviour under aerodynamic loads. The main objective of this research is to develop a fluid-structure interaction (FSI) methodology for predicting deflection of the air dam.

Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) codes are coupled so that fluid pressure and air dam displacement parameters are exchanged. The …

Assessing The Effectiveness Of Cfd To Solve An Inverse Problem Of Thermal Profiles For The Protodune-Sp Neutrino Detector, Cecilia Anne Streff

Electronic Theses and Dissertations

Computational fluid dynamics (CFD) is a branch of fluid mechanics which is employed to numerically solve complex fluid, heat transfer, and multiphysics problems. Traditionally, CFD techniques are used to solve “forward” problems—using some known information of a system as inputs to a representative model to predict experimental measurements or expected system behavior. The work presented here demonstrates how CFD may be used to solve an “inverse” problem—given limited experimental data and some model, predict (previously unidentified) “input” system (or system model) parameters. The case study for this research uses a validated CFD modeling approach of the liquid argon (LAr) region …

The Design And Validation Of A Uav Propeller Intended For Extremely Low Reynolds Number Environments, Benjamin Hebert

Electronic Theses and Dissertations

Mars exploration and UAV development have both advanced significantly over the past century, and are now being considered in tandem. Currently needed are UAV propellers that can operate in the Martian atmosphere. Flow will be in the range of Re < 20,000, creating extreme conditions not typically examined. A Blade Element Momentum Theory (BEMT) algorithm is developed using a variety of corrections designed specifically for low Reynolds number and rotational flows. Due to both the simplicity of the basic BEMT formulation, corrections are easy to put in place and often necessary to achieve accurate estimates. Aerodynamic coefficients are determined from XFOIL code, and have questionable accuracy in this regime. To account for this, a correction model is developed by comparing XFOIL results to experimental results of airfoils at low Re. This is all tested against a previous low Re propeller experiment. The results of this comparison are used to adjust the values in the correction, to produce more accurate results for theoretical design.

From here, a design philosophy for the propeller is developed using established methods and previous experimental data. High thrust is prioritized, with efficiency being a secondary concern. A hard mach limit of 0.7 is set to avoid major drag penalties, limiting the usable ranges of RPM and radius. Airfoil designs are then examined, based on previous designs, theoretical intuition, and …

Reduced-Order Model Predictions Of Wind Turbines Via Mode Decomposition And Sparse Sampling, Ala' Eyad Qatramez

Electronic Theses and Dissertations

Wind turbine wakes are dominated by several energetic turbulent coherent structures that oscillate at specific Strouhal numbers. Implications on wind power harvesting of these dynamic, induced features require accurate unsteady modeling. Dynamic mode decomposition (DMD), a data-driven modal analysis, has demonstrated the ability to identify flow features based on specific frequencies. In this work, the selection of modes and data-driven DMD models pertaining to wakes with constant Strouhal number coherent structures are investigated using physically-informed criteria and sparse sampling. Both criteria are validated with a low Reynolds number flow behind a square cylinder. Next, the techniques are applied to data …

Numerical Prediction Of Automotive Underhood Airflows Using An Uncalibrated Fan Body Force Model, Palak Saini

Electronic Theses and Dissertations

Underhood vehicle airflow simulations are an important part of the overall vehicle thermal management process, especially in the preliminary stages of the vehicle development program when performing experimental work on cooling system prototypes can prove to be expensive, time-consuming, or simply impossible due to the absence of any physical vehicle prototypes. Accurate prediction of the automotive fan performance, which forms a critical component of the cooling module, is a prerequisite for the optimum sizing and design of heat exchangers, and the rest of the under-hood installations. The coupled and complex nature of the under-hood flow environment necessitates consideration of the …

Thermal Modeling Of Permanent Magnet Synchronous Motors For Electric Vehicle Application, Pratik Roy

Electronic Theses and Dissertations

Permanent magnet synchronous motor (PMSM) is a better choice as a traction motor since it has high power density and high torque capability within compact structure. However, accommodating such high power within compact space is a great challenge, as it is responsible for significant rise of heat in PMSM. As a result, there is considerable increase in operating temperature which in turn negatively affects the electromagnetic performance of the motor. Further, if the temperature rise exceeds the permissible limit, it can cause demagnetization of magnets, damage of insulation, bearing faults, etc. which in turn affect the overall lifecycle of the …

Using Computational Fluid Dynamics To Accurately Model Agricultural Spray Nozzles, Zachary Chapman

Electronic Theses and Dissertations

Computational fluid dynamics (CFD) is a tool used by engineers in many industries to study fluid flow. A relatively new industry to adopt the use of CFD is the agricultural industry. The present work seeks to understand whether CFD can be used to accurately model spray nozzles. A spray nozzle commonly used in agricultural spraying was simulated. First, the impact of factors such as mesh size, mesh type, and physics models have on the solution were investigated. Next, a method to pulse the spray was determined. This was required to compare simulation results with experimental data. A user-defined function was …

Comparison Of Hybrid Multi-Dimensional Models Of A Bi-Stable Load-Switched Supersonic Fluidic Oscillator Application, Lovepreet Singh Sidhu

Electronic Theses and Dissertations

Fluidic oscillators are devices capable of superimposing large pressure and velocity fluctuations on the flow through a device without the necessity of having any moving parts. The lack of moving parts makes these devices superior to conventional moving-part valves in high temperature applications. The specific application of interest in the current study is the super-plastic forming (SPF) process in which large sheets of aluminum at very high temperature are formed into the desired shape by pressurizing one side inside the SPF chamber. It is known that the introduction of pressure fluctuations onto the increasing pressure in the SPF chamber reduces …

Quantifying The Performance Of The Protodune Single Phase Neutrino Detector Using Computational Fluid Dynamics, Dillon Pedersen

Electronic Theses and Dissertations

The goal of this research is to provide scientifically-valid computationally generated data of the flow, thermal, and impurity data of the ProtoDUNE single phase detector. Results are compared and validated against an actual detector that is currently being utilized to collect temperature and impurity data. This research will investigate the flows inside these detection chambers using computational fluid dynamics to find approximate solutions to the governing equations of fluid mechanics. Impurity and flow data will allow researchers to determine if results collected are being obstructed by high levels of impurity. Novel approaches have been developed to strike a balance between …

Energy Harvesting From Natural Water Flow, Haonan Kong

Electronic Theses and Dissertations

The hydrokinetic energy contained in flowing water is plentiful and has the potential to be one of the environmentally friendly renewable sources of energy that can be harvested. A new energy harvesting system utilizing Vortex-induced Vibration (VIV) is presented and analysed in this thesis. The proposed energy harvester generates power by direct conversion of the hydrokinetic energy of water flow into mechanical vibrations. The harvester experiences alternating fluid forces due to the repeatable pattern of alternating vortices shed from the sides of the body which generates a wake with Von Kármán Vortex Street. The proposed harvester consists of two coupled …

Analysis Of Flow Structures Around Inclined Bluff Bodies, Kohei Fukuda

Electronic Theses and Dissertations

This thesis uses numerical investigations to examine details of the turbulent flow past bluff bodies, in particular around various inclined flat plate configurations. The study consists of three phases: (1) flow past an infinitely long inclined flat plate, (2) flow past a finite length inclined flat plate near a wall and (3) flow past a stand-alone solar panel with support structure. In Phase 1, the development of three-dimensional fluid structures around an infinitely long inclined flat plate at Reynolds number of 1.57×105 is reported. The Detached Eddy Simulation (DES) is validated against well-established experimental data. The flow analysis in two-dimensional …

An Investigation Of Agricultural Produce Cooling Tunnel Performance, Jean-Paul Edward Martins

Electronic Theses and Dissertations

The goal of this research is to numerically and experimentally investigate the performance of a forced air agricultural produce cooling tunnel. A porous medium approach is used to represent the produce within the containers in the numerical model. The pressure loss coefficients associated with the porous media are determined experimentally, while the heat transfer coefficients are obtained using empirical relationships from the literature. Full scale experimental studies, within a production setting, indicate a high variation in initial product temperatures and varying cold room temperatures over time. The numerical model is modified based on these findings and compared with experimental results. …

Hydrodynamics Of Accumulators Of Compressed Air For An Uwcaes Plant, Ahmadreza Vaselbehagh

Electronic Theses and Dissertations

The present document is a manuscript-based dissertation covering Ahmadreza Vasel-Be-Hagh's PhD research from September, 2011 to May, 2015. The research was particularly focused on studying hydrodynamics of underwater accumulators of compressed air for an underwater compressed air energy storage (UWCAES) plant. The accumulator units were floral configurations of droplet-shaped balloons installed close to the bed of deep water. The research was carried out in two major parts: water flow over the balloons and flow produced by the bursting of the balloons. In the first part, three-dimensional simulations were conducted to investigate water flow over accumulators. The simulation was carried out …

Computational Fluid Dynamics Modeling Of The Effects Of Water Injection In A Diesel Engine, Rabun Z. Wallace

Electronic Theses and Dissertations

Water injection has been used in internal combustion engines for many years. It has been used to cool combustion temperatures, reduce emissions, and in some instances clean carbon buildup from the cylinder. Research has shown that the water to fuel mass ratio is most effective between 20-30%, so the upper and lower limit were used for simulations in Converge CFD. To validate the CFD model, a case without water injection was compared to experimental data from Sandia National Laboratory. The predicted in-cylinder pressure and heat release rate showed good agreement with the experimental data. Cases were run with the injection …

Simulating Self Pressurization In Propellant Tanks Using An Energy Of Fluid Approach, Amanda Paige Winter

Electronic Theses and Dissertations

Recent studies focusing on predicting the self pressurization play a significant role in the design of cryogenic storage systems since tank pressure must be controlled for long duration space missions. Incident solar radiation heats the fluid in the tank over time vaporizing the cryogenic liquid. As the liquid vaporizes, the tank pressure increases. The objective of the current research is to develop a finite volume based Computational Fluid Dynamic (CFD) model of tank pressurization in reduced gravity using an Energy of Fluid (EOF) approach. The FLUENTpressure-based computational model is significantly enhanced to include the EOF method, which will solve the …

Computational Fluid Dynamics (Cfd) Modeling Of A Laboratory Scale Coal Gasifier, Kiel S. Schultheiss

Electronic Theses and Dissertations

Furthering gasification technology is an essential part of advancing clean coal technologies. In order to seek insight into the appropriate operations for the formation of synthetic gas (syngas) a numerical simulation was performed to predict the phenomena of coal gasification in a laboratory scale entrained-flow coal gasifier. The mesh for the model was developed with ICEM CFD software and the chemical and physical phenomena were modeled using the fluid flow solver ANSYS FLUENT. Mesh independence was verified. The model was validated with experimental data from several studies performed on a laboratory scale gasifier.

Systematic examination of the model was performed …

Feature-Based Neuro-Symbolic Networks For Global Diagnostics, Tracy Lynn Schantz

Electronic Theses and Dissertations

Engineered system diagnostics have been researched over the years with many successful results. From transportation systems to office technologies, many have been equipped with self-diagnostic capabilities and are called Smart Machines. In spite of these advances, current diagnostic systems are driven by direct sensory information without much concern for patterns of the system behavior or features associated with them. For large-scale systems with complex dynamics, global as well as local diagnostics become of great importance, where sensory information is used as input for the local diagnostics, and patterns of behavior or features are utilized for global diagnostics.

The main objective …

Meshless Hemodynamics Modeling And Evolutionary Shape Optimization Of Bypass Grafts Anastomoses, Zaher El Zahab

Electronic Theses and Dissertations

Objectives: The main objective of the current dissertation is to establish a formal shape optimization procedure for a given bypass grafts end-to-side distal anastomosis (ETSDA). The motivation behind this dissertation is that most of the previous ETSDA shape optimization research activities cited in the literature relied on direct optimization approaches that do not guaranty accurate optimization results. Three different ETSDA models are considered herein: The conventional, the Miller cuff, and the hood models. Materials and Methods: The ETSDA shape optimization is driven by three computational objects: a localized collocation meshless method (LCMM) solver, an automated geometry pre-processor, and a genetic-algorithm-based …