# Browsing by Subject "Drag"

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Item A subgrid approach for unresolved topography in shallow water hydrodynamic modeling(2016-12) Shin, Gihye; Hodges, Ben R.; McKinney, Daene C.; Lawler, Desmond F.; Cardenas, M. Bayani; Passalacqua, PaolaShow more This study develops methods to represent the effect of subgrid scale topography for shallow water hydrodynamic models using Cartesian grids. Neglect of subgrid scale topographic variability is recognized as causing misrepresentation of wetting and drying processes (Defina, 2000). Subgrid topography has been previously parameterized at model-resolved grid scales using data from high-resolution digital elevation models to capture flow area and volume effects (e.g. Casulli, 2009), but proposed approaches have neglected key aspects of flow resistance. Form drag exerted by unresolved subgrid features cannot be arbitrarily neglected for shallow flow dynamics as it introduces complexity through directional variability. That is, the conventional approach to modeling subgrid frictional effects is through drag coefficients that apply identically to all flow directions through a grid cell; however, subgrid features can introduce directional bias through form drag, e.g. an embankment that blocks flow in only one direction. In the present work, two new model schemes were developed to address the frictional forcing on subgrid scale. These schemes are extensions of the subgrid modeling ideas of Volp et al. (2013) and Casulli (2009). The first new scheme is a subgrid drag model that determines directional drag coefficients representing the integrated and directionally-biased effects of subgrid drag. The second new scheme is a subgrid momentum model using the integrated fluxes through faces of a grid cell to represent subgrid forces and acceleration at the resolved-scale interface between two grid cells. The combination of these two methods is demonstrated to provide an approach to representing subgrid physical processes that have been missing in prior models. The new subgrid models were implemented in the Fine Resolution Environmental Hydrodynamics Model (Frehd) and validated using model-model comparisons at fine and coarse grid resolution. The validation test cases use real-world estuarine topography of a section from a 1×1 m lidar survey of the Nueces River Delta (Texas, USA). The new subgrid models are shown to reduce discrepancies between coarse-grid and fine-grid simulations over the time-space domain. Of key importance is that the new models can represent the flow deflection by subgrid topographic obstructions that cannot be captured without directional drag coefficients. This study indicates that application of the new subgrid modeling approaches can reduce grid-scale dependency that otherwise requires finer grid resolution to adequately capture flow physics.Show more Item Application of Euler-Bernoulli finite element methods for torque and drag model verification(2022-12-02) Elyas, Odai Alaa; Foster, John T., Ph. D.; Landis, ChadShow more As the industry extends its search for hydrocarbons in remote locations, efficient extended reach drilling operations become crucial to reaching subsurface targets. This starts with enhanced simulation and monitoring of real time data measurements. Torque and drag are two of the most important parameters that are monitored continuously throughout any oil and gas drilling operations. Where torque is defined as the force of rotation between the drill pipe and the wellbore wall and drag is defined as the force required to push or pull the drill pipe through the wellbore and formations. The two parameters are often used as indicators for downhole conditions and must be maintained within certain ranges to ensure successful drilling to the targeted depths and running in hole the required completion equipment. Prior to any drilling operation, an estimate of both torque and drag are calculated based on the known drilling fluid properties, and formation parameters. Which is then used as an indicator of drilling issues such as wellbore collapse, cuttings accumulation, and change in drilling fluid properties. Several analytical models are utilized for torque and drag calculation. The first, and widely used approach is the soft string model which assumes the drill pipe acts as soft string taking the shape of the wellbore. This assumption neglects additional forces that cause the drill pipe to bend in deviated locations, which often results in underestimating torque and drag measurements in complex well designs. To address this, a stiff string model was implemented which considers the pipe’s bending stiffness and its effects on torque and drag calculations. Additionally, finite elements analysis (FEA) has been implemented to validate torque and drag calculations throughout the industry. However, the application of FEA often includes mesh generations which creates a 3D model of the drill pipe and subdivides the object into smaller domains to perform the calculations across the entire volume. This approach typically requires special software or large computational power to perform the calculations in a timely manner for real time monitoring applications. This thesis presents an approach to FEA that utilizes the Euler-Bernoulli beam equations, with the addition of an axial forces component to address both axial and transverse forces and deformations. The outcome of this thesis provides an accurate representation of torque and drag calculations, performed efficiently which could be used for planning, and real time monitoring during drilling operations.Show more Item "Are you getting angry Doctor?" : Madea, strategy and the fictional rejection of black female containment(2014-05) Faust, Mitchell R.; Richardson, Matt, 1969-Show more Within the scope of this thesis, I provide close textual and visual readings of director/actor/producer Tyler Perry's most well-known character, Mable "Madea" Simmons -- a performance he does in full female drag attire -- focusing on his mainstream hit film, Madea Goes to Jail (2009). My reading of the character of Madea veers against the common narrative her existence being just another recycled trope of men disguised as women only to perform in stereotypical and demonizing behavior. I argue Madea represents what I refer to as a "trans*female character", within the space of Perry's popular film that feature her. Read through the lens of being trans*female character, I propose this shift in analysis and critique of cinematic displays of drag helps to transgress beyond male/female binaries of acceptable and possible visual gender representations. More in-depth, using the theoretical concept of Gwendolyn Pough's "bringing wreck", I make the argument that while ostensibly representing the "angry black woman" stereotype, Madea's characterization and actions within the film represent strategies and efforts to not be contained within hegemonic ideals of black female respectability politics and the law efforts to put her behind bars. By "bringing wreck", Madea's fictional acts of violence and talking back are read as a strategy that reflects a historical trend of misrecognition that renders black women's concerns and discontent with marginalization as irrational anger.Show more Item Bicha space-time : queer and trans femme spatial practices in Sobral, Ceará(2023-04-21) Rojas, Joseph Luis, Jr.; Leu, LorraineShow more Despite prevailing stereotypes that construct the Brazilian Northeast and non-metropolitan urban spaces as anachronistic and conservative, queer and trans people in a growing number of cities such as Sobral, Ceará, have managed to project themselves onto local, regional, and (trans)national imaginaries. Inspired by Dora Silva Santana’s concept of Afro trans vivências, this thesis centers bicha vivências nordestinas (Northeastern bicha living), understood as the embodied knowledge and resistance of Northeastern queer and trans femmes. I follow a group of college-aged sobralenses primarily consisting of (effeminate) gay men, drag queens, and non-binary and transfeminine folks, and examine the ways in which they adeptly navigate and negotiate different parts of the city in an effort to appropriate spaces for queer and trans sociability. I argue that they queer or trans-form space in Sobral, producing what I call transient geographies, through public performances of femininity and gender nonconformity made possible by fleeting but recurring assemblages of queer people in relationship. I also narrate the embodiments and performances of Rawser, a non-binary gay drag queen who sings in the historically macho genre of forró, and Malika, a black trans artist who translocalizes cultural forms such as ballroom and slam poetry. I argue for techniques of transfemmation as a framework for understanding the methods or tactics by which ephemeral performances of femininity and gender non-conformity, such as those modeled by Rawser and Malika, may queer or trans-form space. Collectively, my interlocutors complicate standard depictions of the region, contest social norms, disrupt the expected uses of (symbolic) space, and demonstrate some of the creative ways in which queer and trans femme spatial practices work within, alongside, and against otherwise cisheteronormative geographies.Show more Item Isogeometric analysis : applications for torque and drag models, drillstring and bottom-hole assembly design(2018-05) Hanson, Katy Lynn; Oort, Eric van; Foster, John T., Ph. D.Show more The drilling industry today relies on torque and drag models to analyze and ensure success during all phases of well construction and operations, including planning, drilling, and completion. Analytical models are based on equations that are undergoing constant development and improvement. The finite element method is an alternative to complex analytical calculations that is used often to determine torque and drag forces that are present when a drillstring is lowered, raised, and rotated in a wellbore. Traditional finite element analysis (FEA), however, is not time efficient or computationally able to simulate the complexities of a real wellbore. Thus, we introduce an alternative to the traditional finite element approach: isogeometric analysis. Isogeometric analysis is similar to finite element analysis except that it uses NURBS (Non-Uniform Rational B-Splines), as opposed to interpolatory polynomials used in traditional FEA, as the basis functions. NURBS functions are the same as those used in CAD programs, and they are able to construct exact conic shapes, such as circles and ellipses. Adopting NURBS basis functions allows finite element analysis to be performed directly on the exact geometrical surface - not on an approximate geometric surface mesh, as in traditional FEA. IGA yields a significantly faster and more accurate simulation. This thesis presents a real-world application of IGA to a drag force model to determine the resultant surface hook load during run-in-hole (RIH) operations. Real well data is used, and IGA results are compared to a similar FEA analysis. The outcome shows that IGA is indeed a superior finite element method that has immense potential for further application in the industryShow more Item Pahoehoe, aa, and blocky lavas(2009-03) Barker, Daniel S.Show more Item Passing between poses(2022-09-22) Wood, Ariel Rosamonde; Birchler, Alexander, 1962-; Richmond-Garza, Elizabeth; Stoney, John S; Hubbard, Teresa; Sutherland, Daniel D; Reynolds, Ann MShow more In my practice, I make objects and structures that evoke plumbing and drainage. I inhabit this formal lexicon to complicate concepts of bodies, space, and time. Working primarily with sculpture, I focus on ceramic, metal, wood, silicone, and rubber. I am drawn to aspects of plumbing that appear strange, silly, or sentimental; a search for the unusual in the usual. The forms I make are arranged in proximity to each other or physically joined to elicit interconnectedness, sensitivity, liminality, and a celebration of queerness. The connection point between materials is a space for tenderness and reciprocity; one in which I seek to show a mutual recognition of responsibility and contingency.Show more Item Proximity operations of nanosatellites in Low Earth Orbit(2013-12) Almond, Scott Douglas; Lightsey, E. GlennShow more A mission architecture consisting of two NASA LONESTAR-2 satellites in Low Earth Orbit is considered. The craft are equipped with cross-communication radios and GPS units. Analyses are conducted for ejection, thruster and attitude maneuvers to achieve objectives of the mission, including sustained communications between the craft. Simulations are conducted to determine the duration of the communication window following the initial separation of the two craft. Recommendations are made to maximize this window while accounting for attitude constraints and the effects of atmospheric drag. Orbital mechanics and control theory are employed to form an algorithm for filtering GPS position fixes. The orbit-determination algorithm accounts for the effects of drag and Earth’s oblateness. Procedures are formed for verifying the initial separation velocities of two spacecraft and for measuring the velocity imparted by impulsive thruster maneuvers. An algorithm is also created to plan the timing and magnitude of corrective thruster maneuvers to align the orbital planes of the two craft. When the craft pass out of communication range, a ground station is used to relay data and commands to conduct state rendezvous procedures. A plan for coordinated attitude maneuvers is developed to strategically utilize the cumulative effects of drag and orbit decay to align the craft over long time periods. The methodologies developed here extend prior research into close proximity operations, forming the foundation for autonomous on-orbit rendezvous under a broader set of initial conditions.Show more Item Testing geologic and geometric effects on drilling operations using torque and drag models(2015-12) Ho, Anthony, M.S. in Engineering; Gray, Kenneth E., Ph. D.; Daigle, HughShow more Intuitively, geologic and geometric effects on torque and drag should be significant. But literature suggests otherwise. Lesage et al. (1988) wrote that friction coefficients are not affected by lithology and hole angle, among other things. And if friction coefficients are similar for all of these factors, then only inclination, azimuth, and pipe specifications affect torque and drag. My thesis looks to test this statement using Johancsik’s torque and drag model and data provided by our sponsors. Johancsik’s model was chosen to test these effects because it is the most widely used torque and drag model in industry. Johancsik’s model also only relies on surface data in order to conduct an analysis. This contributes to the widespread use of Johancsik’s model and therefore increases the applicability of this paper. Once Johancsik’s model was chosen, it became natural to choose the minimum curvature method to interpolate the wellbore trajectory because Johancsik’s model was designed using the minimum-curvature method. Also, the minimum curvature method is the most widely used wellbore-interpolation method in industry. By using the minimum curvature method, this paper increases its applicability to industry. The analyses were conducted by examining the friction coefficients of each individual formation and lithology and geometric section. Friction factors encompass all factors that are not explicitly captured by the model and any factors affecting torque and drag that are not in the model will be captured by the friction factors. This study found lithology effects to affect drag consistently, though more data is needed. Drag friction factors were consistent by lithology, though they did appeared less predictable in Dataset 1 than the Datasets 2 and 3. Lithology affected torque less consistently than it did drag, though again more data is needed. Again, the results from Dataset 1 appeared to differ from Datasets 2 and 3. Further analyses are needed to conclude if this is caused by factors unrelated to lithology or individual geologies. The geometric effects of curved versus straight sections appear to not affect torque and drag. The results from the curved sections from the analyses have little relation to each other. As for more specific geometries, more analyses are needed before conclusions can be reached.Show more