Engineering Commons^™

Effect Of Swirl Ratio On Simulated Vortech Chamber Vortex Parameters, Samuel Kolar

Civil Engineering Undergraduate Honors Theses

A numerical simulator can use computational fluid dynamics (CFD) to model an experimental tornado-simulating chamber at Texas Tech University (known as VorTECH). Previous studies evaluating this particular CFD model have produced results that compare the touchdown swirl ratio (S_TD), core radius (r_c), maximum tangential velocity at touchdown (V_tmax @ S_TD), and height of the maximum tangential velocity (z_c) reasonably well with experimental data from the VorTECH facility. The effects of swirl ratio beyond S_TD on important vortex parameters including r_c, V_tmax, z …

Field Flow Measurements For Pipe Installations With Non-Ideal Conditions, Jake Douglas

All Graduate Theses and Dissertations, Fall 2023 to Present

Accurate flow measurement data is necessary to effectively manage water resources. The purpose of this research is to investigate options to improve field flow measurement by investigating alternatives for calibrating flow meters installed in non-ideal piping. Typically, to accurately measure a flow rate using most types of flow meters, it is recommended that a straight section of pipe be installed immediately upstream and downstream of the flow meter to avoid flow fluctuations at the meter location. However, in many cases, flow disturbances upstream of the meter are unavoidable.

The performance of field flow measurements in non-ideal piping scenarios were studied …

Computational Modeling Of Patterned Membranes And Spacers For Improved Hydrodynamics And Fouling Reduction In Reverse Osmosis Water Treatment Processes, Zuo Zhou

All Dissertations

My research goal is to discover ways to improve the hydrodynamics of reverse osmosis (RO) membrane systems through creative membrane surface patterning and spacer designs. Since concentration polarization (CP) usually promotes membrane fouling, improving hydrodynamics would result in reduced fouling and better membrane performance. With computational fluid dynamics (CFD), we can explore dozens or even hundreds of models with different geometries and boundary conditions. Through plotting their velocity profile, streamlines, shear stress, pressure profile, concentration profile, and so on, we can determine which design would lead to the best performance.

At first, patterned membranes were evaluated and compared with flat …

Using Computational Fluid Dynamics To Predict Flow Through The West Crack Breach Of The Great Salt Lake Railroad Causeway, Michael Rasmussen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Great Salt Lake in Utah, USA, is a terminal, saline lake and is divided into two primary sections (northern and southern) by an east-to-west railroad causeway. Shortly after completion of the earth-fill causeway in the late 1950s, the two sections became dramatically different with differences in water surface elevation and water density. These differences cause the formation of a unique flow behavior commonly referred to as a density-driven exchange flow or bi-directional flow; a behavior observed in other lake and ocean settings where two fluids of differing densities interact. Measuring these exchange flows is a priority for lake managers …

Using Experiments, 3d Scanning, And Computational Fluid Dynamics To Analyze Variance In Minor Loss Coefficients, Adam B. Pack

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As water moves through pipes, it loses energy. The energy losses are due to friction and the minor losses associated with various pipe fittings, which change the direction of flow. Pipe bends, or elbows, are a common pipe fitting and a significant source of energy loss in piping systems. This research was performed to better understand the variability of energy loss due to different pipe elbow designs and to investigate methods to replicate these losses using numerical simulations.

Eight pipe elbows, all 3-inch, 90-degree, schedule 40 PVC elbows that vary by radius of curvature and/or end connection type, were tested …

Computational Study Of Dense Gas Dispersion In Urban Areas, Rasna Sharmin

All Dissertations

A series of steady-state simulations have been conducted to investigate removal of dense gas from a simple square canyon formed between two square cross-section obstacles. Due to urbanization and industrialization, there always lies a high risk of exposure to harmful pollutants which can result from accidental release of toxic gasses. Those are often denser than the atmosphere. and can easily get trapped in between buildings in urban canopies. It is important to have full understanding of flushing mechanism of dense fluid inside urban canopies by steady turbulent flow because the exposure to these toxic dense gasses can be catastrophic. There …

Towards Simulation Of Complex Ocean Flows: Analysis And Algorithm For Computation Of Coupled Partial Differential Equations, Wenbin Dong

Dissertations and Theses

The hybrid CFD models which usually consist of 2 sub-models, develop our capability to simulate many emerging problems with multiphysics and multiscale flows, especially for the coastal ocean flows interacted with local phenomena of interest. For most cases, the sub-models are connected with direct interpolation which is easy and workable. It becomes urgently needed to investigate the inner mechanism of such model integration as this simple method does not work well if the two sub-models are different in governing equations, numerical methods, and computational grids. Also, it can not treat complex flow structures as well as the balance in mass …

Venturi Meter Performance When Installed On The Branch Of A Tee Junction With Converging Run Flow, E. Elliot Naulu

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Venturi flow meters are often installed downstream of disturbances such as a tee junction, valve, or elbow. In such a case, a laboratory calibration may be needed to measure the Venturi meter’s performance under said limitations so that accurate metering is achieved. However, in some cases, laboratory calibration may not be possible.The purpose of this research was to investigate Computational Fluid Dynamics (CFD) ability to simulate a Venturi meter installed on the branch of a tee junction with converging run flow.

This study used CFD to compare against laboratory results to illustrate CFD’s capability as a calibration method. The results …

Numerical Simulation Of Losses In Four-Way Pipe Junctions, Simon Barth

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To design pipelines, engineers need to know how much energy the fluid in the pipe has at different locations in the pipe network. The energy the fluid has comes in the form of pressure, velocity, and elevation. As fluid travels through a pipe, it loses energy for many different reasons. Some of those reasons include friction between the fluid and the pipe wall, shear forces within the fluid, changes in flow direction, changes in elevation, or various pipe fittings like elbows, tee’s, valves, reducers, and expanders. Many of the causes of energy loss are well researched. One cause of energy …

Venturi Flowmeter Performance Installed Downstream Of The Branch Of A Tee Junction, Benjamin G. Sandberg

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this research was to evaluate the influence of a tee junction on flow rate measurement of a Venturi flowmeter installed downstream of the branch of a tee. Accuracy in flow measurement is important to organizations where miscalculated flow rates can add up to be millions of dollars in either lost revenue, overcharges to the client, or improper system operation. This research used Computational Fluid Dynamics (CFD) to determine ratios by which the manufacturer’s straight-line calibrated C_d (discharge coefficient) can be adjusted to improve the accuracy of the flow measurement when the Venturi is installed on the …

Safety Assessment Of Road Vehicle In Crosswind Considering Driver Behavior, Jiexuan Hu

LSU Doctoral Dissertations

With expansion of the economy, more and more highway networks extend to coastal areas and mountain valley areas. Vehicles will be exposed to strong crosswinds when driven on these highway roads, especially in hurricane season and in winter in these two different topographic areas. Strong crosswinds threaten the safety of transportation infrastructure and passing vehicles in forms of vehicle accidents that usually result in traffic blockage and driver injury, posing negative effects on economic growth. This dissertation aimed to evaluate the vehicle safety when running through crosswinds in consideration of driver behaviors.

Firstly, the aerodynamic characteristics of road vehicles were …

Optimization Of Window Confirguration In Buildings For Sustainable Thermal And Lighting Performance, Meseret Tesfay Kahsay

Electronic Thesis and Dissertation Repository

In recent years, there is an urban architectural evolution towards significant use of glazing in high-rise buildings. Windows play a critical role in moderating the elements of the climate. Although good for outdoor viewing and daylighting, glazing has very little ability to control heat flow and solar heat gain. As a result, about 20 - 40% of the energy in a building is wasted through windows. Finding an optimal configuration of windows is a complex task due to its conflicting objectives, such as outdoor view, daylighting, and thermal comfort demands. Further buildings interact with the microclimate in a complex manner, …

Numerical Simulation For The Hydrodynamic Performance Of Hydropower Turbine Near Free Surface, Zeda Yin

Theses, Dissertations and Capstones

The performance of hydropower turbine in shallow water can be affected by the presence of free surface. Therefore, it is of great interest to investigate the influence of free surface on hydropower turbine performance through computational simulations. For a better understanding of flow field around hydropower turbine operating in shallow water, it is important to analyze the flow over a single hydrofoil beneath free surface first. Therefore, as the first part of this thesis, the Computational Fluid Dynamics (CFD) methodology was used for numerical simulation of 2D unsteady incompressible viscous flow over a hydrofoil under the free surface. The computation …

Employing 2-D Cfd & Lrb Model Around Trees To Improve Vawt Placement, David Chukwuebuka Bassey

All Graduate Theses, Dissertations, and Other Capstone Projects

In the placement of vertical axis wind turbines, trees are a constant presence in the vicinity. They are found to grow at different height and shape configurations. And in areas such as the Minnesota State University, Mankato (MNSU) campus, they serve as blockage to airflow; limiting the efficiency of installed turbines. This work sets the precedent for the validation of vegetative numerical models created for the Xcel Energy Research Development Fund (RDF) project.

Using two-dimensional (2-D) numerical simulations of porous cylinders placed in a rectangular medium of air, insight into the flow profile and distribution in the leeward side of …

Computer Modeling Of Close-To-Ground Tornado Wind-Fields For Different Tornado Widths, Mohammadhossein Kashefizadeh

Graduate Theses and Dissertations

Tornadoes induce different wind forces on buildings than straight-line (SL) winds. The tangential velocity (Vθ) of tornados is the main parameter that causes damage to the buildings. In-field tornado measurements cannot evaluate the tornado’s Vθ at less than 20m above ground level (AGL). The laboratory tornado simulators suggest that the Swirl ratio (S) and the radius (ro) are the most influential factors affecting Vθ. However, due to scaling problems, laboratory simulators cannot report the Vθ for elevations less than 10m AGL. Well refined computational fluid dynamics (CFD) models can evaluate the Vθ at less than 10m AGL. However, the CFD …

Assessment Of Dynamic Effect Of Transmission Line Conductor Longitudinal Reaction Due To Downburst Loading, Ibrahim Ibrahim

Electronic Thesis and Dissertation Repository

Due to the locality and non-stationary nature of downburst wind loading events, their effect on the structural response of transmission line structures is of special nature that differs from conventional atmospheric boundary layer wind loading. Acknowledging such difference, the current thesis aims to quantify the dynamic effect associated with downburst loading on transmission line systems. To achieve that, several steps had to be realized, including experimentally verifying the numerical model used for analysis using wind field that was generated using computational fluid dynamics. The verified model was extended from model scale to full scale, where the wind field used for …

Transformation Of Nonlinear Waves In The Presence Of Wind, Current, And Vegetation, Haifei Chen

Electronic Theses and Dissertations

Accurate prediction of extreme wave events is crucial for the safe maritime activities and offshore operations. Improved knowledge of wave dissipation mechanisms due to breaking and vegetation leads to accurate wave forecast, protecting life and property along the coast. The scope of the thesis is to examine the wave transformations in the presence of wind, current, and vegetation, using a two-phase flow solver based on the open-source platform OpenFOAM. The Reynolds-Averaged Navier-Stokes (RANS) equations are coupled with a Volume of Fluid (VOF) surface capturing scheme and a turbulence closure model. This RANS-VOF model is adapted to develop a numerical wind-wave-current …

The Development And Numerical Modelling Of A Representative Elemental Volume For Packed Sand, Ashraf Thabet

Electronic Thesis and Dissertation Repository

The motivation of this thesis is the development of simple microscopic-scale model (representative elemental volume; REV) that can be used to conduct flow and heat transfer simulations from which closure coefficients can be established for the volume-averaged transport equations for porous media (packed bed). The thesis provides a brief introduction to the computational technique adopted for the geometric generation of the REV (YADE), followed by a parametric study undertaken to reveal the minimum number of particles inside the REV that are required to mimic the appropriate physics. Additional analysis was conducted with the goal of determining the influence of deviation …

Multiscale Wind Modelling For Sustainability And Resilience, Djordje Romanic

Electronic Thesis and Dissertation Repository

The research presented herein is a mix of meteorological and wind engineering disciplines. In many cases, there is a gap between these two fields and this thesis is an attempt to bridge that gap through multiscale wind modelling approaches. Data and methods used in this study cover a multitude of spatial and temporal scales. Applications are in the fields of sustainability and resilience. This relationship between multiscale wind modelling and sustainability and resilience is investigated examining several case studies of three different developments: urban, rural and coastal.

An urban wind modelling methodology is proposed and applied for a specific development …

Bio-Inspired Optimal Fin Shape And Angle For Maximum Surfboard Stability, Megan S. Macneill

Dissertations, Master's Theses and Master's Reports - Open

Wave surfing is a multi-billion dollar industry involving both maneuverability and speed, yet little research has been done regarding optimal fins shape for these competing qualities. The purpose of this master's thesis was to focus on a single fin setup in order to identify a bio-inspired fin shape that maximized lateral stability while minimizing drag forces, in order to increase surfing maneuverability.

The computational fluid dynamic models NX and laboratory experiments performed in a water channel, with lift and drag being directly measured, were used to compare nine fins based on dorsal fins of real fish. To properly compare, fluid …

Numerical Modelling Of Downburst Interaction With Bluff Body, Aditi Jog

Electronic Thesis and Dissertation Repository

The objective of this study is to investigate the interaction of a bluff body with a downburst flow. Numerical investigation of the flow field using CFD analysis was carried out for three different downburst sizes (h/d=1, 2, 4) under suitable boundary conditions subjected to constant jet velocity. The downburst-structure interaction study was conducted for two jet diameters (h/d=1 and 4) and two radial locations from the downburst center.

The results showed that the downburst size greatly dominates the intensity of the flow. The largest downburst resulted in the highest velocity magnitude near the ground and also covered a larger area …

Hazard Classification And Hydraulic Remediation Options For Flat-Topped And Ogee-Crested Low-Head Dams, Riley J. Olsen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The dangerous hydraulic conditions that can form downstream of a low-head dam were investigated. These dangerous hydraulic conditions have been the cause of hundreds of drowning incidents since the construction of the first low-head dams. Two primary objectives were identified for this study, each of which were primarily performed using the Computational Fluid Dynamics software, Flow-3D^®, with physical models used to verify the numerical results. The first objective was the identification of a risk factor made up of easily measured parameters that could accurately predict when the dangerous hydraulic conditions are present at a low-head dam. The risk …

3d Numerical Modeling Of Hydrodynamic Flow, Sediment Deposition And Transport In Stormwater Ponds And Alluvial Channels, Leying Zhang

Civil & Environmental Engineering Theses & Dissertations

Prediction of flow and sediment transport is an important and challenging problem for stormwater management and river engineering applications. This thesis concerns primarily the computation of flow, sediment deposition and transport processes in stormwater ponds and alluvial channels based on a multiphase flow approach in modeling sediment transport. Starting from an existing hydrodynamic Reynolds Averaged Navier-Stokes flow solver, numerical models are developed to predict flow, sediment deposition and transport under the FLUENT software package. Two types of sediment transport models are formulated to consider quantities of present sediment phase volume fractions: a Discrete Phase Model in a Lagrangian frame where …