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Articles 241 - 270 of 278
Full-Text Articles in Engineering
Deformation Of Unstructured Viscous Grids, Denis B. Kholodar, Scott A. Morton, Russell M. Cummings
Deformation Of Unstructured Viscous Grids, Denis B. Kholodar, Scott A. Morton, Russell M. Cummings
Aerospace Engineering
A mesh deformation algorithm for unstructured grids is presented. It is designed for high Reynolds number flow problems. Such grids are employed in aerodynamic and aeroelastic studies of wings or complete aircraft configurations in flows where the viscous effects are important. Given a surface deformation, the method efficiently recalculates new locations of high aspect ratio cells that make up the viscous layers of the grid and then deforms the inviscid part of the grid using an established method based on a torsional spring analogy technique. Results are presented for monitoring the deterioration of the quality of the grid during subsequent …
Performance Of A New Cfd Flow Solver Using A Hybrid Programming Paradigm, M. J. Berger, M. J. Aftosmis, D. D. Mashall, S. M. Murman
Performance Of A New Cfd Flow Solver Using A Hybrid Programming Paradigm, M. J. Berger, M. J. Aftosmis, D. D. Mashall, S. M. Murman
Aerospace Engineering
This paper presents several algorithmic innovations and a hybrid programming style that lead to highly scalable performance using shared memory for a new computational fluid dynamics flow solver. This hybrid model is then converted to a strict message-passing implementation, and performance results for the two are compared. Results show that using this hybrid approach our OpenMP implementation is actually marginally faster than the MPI version, with parallel speedups of up to 599 out of 640 using OpenMP and 486 with MPI.
Modeling And Simulation Research And Instruction At The U.S. Air Force Academy, Russell M. Cummings, Scott A. Morton, Keith Bergeron
Modeling And Simulation Research And Instruction At The U.S. Air Force Academy, Russell M. Cummings, Scott A. Morton, Keith Bergeron
Aerospace Engineering
Modeling and simulation has become a driving force within the engineering and science communities as the cost of, and time for, experimentation continues to rise. Some areas of study, such as chemistry and biology, may not even have the ability to fully evaluate certain processes experimentally, making modeling and simulation even more important. The situation has led many areas of research to the necessity of modeling and simulating various processes using computers. In addition, the rise in computational capabilities (the supercomputers of a decade ago are outmoded by the PC clusters of today), has led to a paradigm shift from …
High Resolution Turbulence Treatment Of F/A-18 Tail Buffet, Scott A. Morton, Russell M. Cummings, Denis B. Kholodar
High Resolution Turbulence Treatment Of F/A-18 Tail Buffet, Scott A. Morton, Russell M. Cummings, Denis B. Kholodar
Aerospace Engineering
Unsteady tail loads of the F/A-18 are computed using various turbulence models at an angle of attack consistent with buffet induced by leading-edge extension vortex breakdown. Comparison of these industry standard turbulence models with the Detached Eddy Simulation (DES) hybrid RANS-LES approach reveals the inadequacies of RANS methods and the ability of DES to reproduce the observed unsteadiness at these conditions. Computed vortex breakdown position and frequencies of the DES method are shown to be accurate by comparison to flight test and experimental results. Finally, comparison of the DES unsteady tail pressures with flight-test tail pressures reveal the ability of …
Airplane Design And The Biomechanics Of Flight – A More Completely Multi- Disciplinary Perspective, John H. Mcmasters, Russell M. Cummings
Airplane Design And The Biomechanics Of Flight – A More Completely Multi- Disciplinary Perspective, John H. Mcmasters, Russell M. Cummings
Aerospace Engineering
Aeronautics is usually presumed to have started as a formal engineering discipline somewhere in historical time between the mythological experiments of Daedalus and his ill-fated son, Icarus; and the dreams and schemes of Leonardo da Vinci during the Italian Renaissance. As reviewed in this paper, “aeronautics” has a far longer history, extending over a period of about 300 million years beginning with the evolution of the ability of insects to fly. With the advent of the success of the Wright brothers, technologists quickly turned their attention from the inspirations and lessons provided by natural models of flying machines to …
Some Systemic Issues In The Development Of The Aerospace Industry Technical Workforce Of The Future, John H. Mcmasters, Russell M. Cummings
Some Systemic Issues In The Development Of The Aerospace Industry Technical Workforce Of The Future, John H. Mcmasters, Russell M. Cummings
Aerospace Engineering
This paper is a continuation of the authors’ previous examinations of a suite of issues surrounding the putative decline in aeronautics in this country. The purpose of this paper is to discuss three specific issues believed to be of particular importance to the future of our industry. The first is the question of how many engineers we may need in our future as we confront the problem of an aging workforce and the globalization of our industry. The second is the question of what skills and abilities these engineers will need to possess as the overall industry continues to evolve. …
Detached-Eddy Simulation Of Slat And Flap Aerodynamics For A High-Lift Wing, Russell M. Cummings, Scott A. Morton, James R. Forsythe
Detached-Eddy Simulation Of Slat And Flap Aerodynamics For A High-Lift Wing, Russell M. Cummings, Scott A. Morton, James R. Forsythe
Aerospace Engineering
Three-dimensional multi-element wings are simulated to investigate slat and flap aerodynamics using Detached-Eddy Simulation. The computations are performed by solving the Navier-Stokes equations on unstructured grids. All of the computed cases include the main wing with a half-span flap deflected to 39 degrees and a three-quarter-span slat deflected to 6 degrees. Computations of the model, which simulates a landing configuration at 10 degrees angle of attack and a chord-based Reynolds number of 3.7 million, are validated with surface pressure measurements acquired at the NASA Ames 7- by 10-Foot Wind Tunnel. The results increase the computational knowledge of how to accurately …
An Embedded Boundary Cartesian Grid Scheme For Viscous Flows Using A New Viscous Wall Boundary Condition Treatment, David D. Marshall, Stephen M. Ruffin
An Embedded Boundary Cartesian Grid Scheme For Viscous Flows Using A New Viscous Wall Boundary Condition Treatment, David D. Marshall, Stephen M. Ruffin
Aerospace Engineering
This work presents a new viscous wall boundary condition technique for embedded Cartesian grid schemes in order to model laminar viscous flows. The development of viscous effects modeling using pure Cartesian grids with cut cells at the surface has been hampered by the widely varying control volume sizes associated with the mesh refinement and the cut cells associated with the solid surface. This scheme removes the cells adjacent to the surface from the control volume formulation. These cells are instead solved via an interpolation technique which utilizes the wall boundary conditions to build the interpolating functions. Two different interpolation techniques …
A New Inviscid Wall Boundary Condition Treatment For Embedded Boundary Cartesian Grid Schemes, David D. Marshall, Stephen M. Ruffin
A New Inviscid Wall Boundary Condition Treatment For Embedded Boundary Cartesian Grid Schemes, David D. Marshall, Stephen M. Ruffin
Aerospace Engineering
This work presents a new inviscid wall boundary condition technique for embedded Cartesian grid schemes. This scheme eliminates the time step restrictions associated with the arbitrarily small control volumes that can result when the surface cuts the Cartesian control volumes. The cells adjacent to the surface are removed from the control volume formulation and are instead solved via an interpolation technique which utilizes the wall boundary conditions to build the interpolating functions. Two different interpolation techniques are presented, one without considering wall curvature and one considering wall curvature. Results are compared to a two-dimensional airfoil case and a three-dimensional wing …
Fifty Years Of Hypersonics: Where We've Been, Where We're Going, John J. Bertin, Russell M. Cummings
Fifty Years Of Hypersonics: Where We've Been, Where We're Going, John J. Bertin, Russell M. Cummings
Aerospace Engineering
Hypersonic flight has been with us since 22 September 1963, when Robert M. White flew the North American X-15 at 4520 mph at an altitude of 354,200 ft—a Mach number of 6.7! This remarkable achievement was accomplished over six decades due to intensive research and development by a large number of scientists and engineers. In spite of that momentous achievement, designers have found the hypersonic environment to be harsh and non-forgiving. New programs since the 1960s have often uncovered the unknown unknowns, usually the hard way—early flights of new systems have often revealed problems of which the designers were …
Computational Challenges In High Angle Of Attack Flow Prediction, Russell M. Cummings, James R. Forsythe, Scott A. Morton, Kyle D. Squires
Computational Challenges In High Angle Of Attack Flow Prediction, Russell M. Cummings, James R. Forsythe, Scott A. Morton, Kyle D. Squires
Aerospace Engineering
Aircraft aerodynamics have been predicted using computational fluid dynamics for a number of years. While viscous flow computations for cruise conditions have become commonplace, the non-linear effects that take place at high angles of attack are much more difficult to predict. A variety of difficulties arise when performing these computations, including challenges in properly modeling turbulence and transition for vortical and massively separated flows, the need to use appropriate numerical algorithms if flow asymmetry is possible, and the difficulties in creating grids that allow for accurate simulation of the flowfield. These issues are addressed and recommendations are made for further …
Multidisciplinary Applications Of Detached-Eddy Simulation To Separated Flows At High Reynolds Numbers, Scott A. Morton, Matt Steenman, Russell M. Cummings, James R. Forsythe, Kenneth E. Wurtzler, Kyle D. Squires, Shawn H. Woodson, Phillippe R. Spalart
Multidisciplinary Applications Of Detached-Eddy Simulation To Separated Flows At High Reynolds Numbers, Scott A. Morton, Matt Steenman, Russell M. Cummings, James R. Forsythe, Kenneth E. Wurtzler, Kyle D. Squires, Shawn H. Woodson, Phillippe R. Spalart
Aerospace Engineering
We focus on multidisciplinary applications of detached-eddy simulation (DES), principally flight mechanics and aeroelasticity. Specifically, the lateral instability (known as abrupt wing stall) of the preproduction F/A-18E is reproduced using DES, including the unsteady shock motion. The presence of low frequency pressure oscillations due to shock motion in the current simulations and the experiments motivated a full aircraft calculation, which showed low frequency high-magnitude rolling moments that could be a significant contributor to the abrupt wing stall phenomenon. DES is also applied to the F-18 high angle of attack research vehicle (HARV) at a moderate angle of attack to reproduce …
Computational Simulation And Piv Measurements Of The Laminar Vortical Flowfield For A Delta Wing At High Angle Of Attack, Russell M. Cummings, Scott A. Morton, Stefan G. Siegel
Computational Simulation And Piv Measurements Of The Laminar Vortical Flowfield For A Delta Wing At High Angle Of Attack, Russell M. Cummings, Scott A. Morton, Stefan G. Siegel
Aerospace Engineering
The low-speed, laminar flowfield for a 70°-sweep delta wing is investigated. Solutions to the unsteady, three-dimensional, compressible Navier-Stokes equations were obtained on an unstructured grid to match results from an experiment performed in a water tunnel. The experiment was conducted with the delta wing at an angle of attack of 35° and the freestream flow at a root-chord Reynolds number of 40,700. The computational results are analyzed and compared with the experimental results in order to show how computations and experiments can be conducted in a synergistic fashion. Details about the primary vortex location, vortex burst, secondary vortex, and shear …
Des Grid Resolution Issues For Vortical Flows On A Delta Wing And An F-18c, Scott A. Morton, Mathew B. Steenman, Russell M. Cummings, James R. Forsythe
Des Grid Resolution Issues For Vortical Flows On A Delta Wing And An F-18c, Scott A. Morton, Mathew B. Steenman, Russell M. Cummings, James R. Forsythe
Aerospace Engineering
An assessment of unstructured grids for use in Detached-Eddy Simulations (DES) of vortical flowfields over two configurations, a 70 degree delta wing and an F-18C are presented. The role of the grid in detached eddy simulations of vortical flowfields, including complex features such as vortex breakdown, is assessed on a delta wing with comparison to wind tunnel data. Adaptive mesh refinement is applied to the delta wing grid to improve the focus region aft of the vortex breakdown where massively separated flow exists and unsteady pressures are generated that could impact the loads on vertical tails of more complex configurations. …
A Multifaceted Approach To The Aiaa Foundation Undergraduate Team Aircraft Design Competition, Russell M. Cummings, Aaron R. Byerley
A Multifaceted Approach To The Aiaa Foundation Undergraduate Team Aircraft Design Competition, Russell M. Cummings, Aaron R. Byerley
Aerospace Engineering
A multifaceted, novel approach was used to help students create entries for the AIAA Foundation Undergraduate Team Aircraft Design Competition. Each entry involved the design, analysis, construction, and testing of the aircraft. Three groups were involved for each airplane: the first group was responsible for the airframe, the second group was responsible for the engine, and the third group was responsible for the construction and flight testing of a radio-controlled flying model. There was an overall Chief Executive Officer who insured that engine-airframe integration issues were addressed. Students from a variety of majors, both technical and non-technical, participated in various …
A Method For Thermodynamic Work Potential Analysis Of Aircraft Engines, Robert Mcdonald
A Method For Thermodynamic Work Potential Analysis Of Aircraft Engines, Robert Mcdonald
Aerospace Engineering
The objective of this paper is to provide a tool to facilitate the application of thermodynamic work potential methods to aircraft and engine analysis. This starts with a discussion of the theoretical background underlying these methods, which is then used to derive various equations useful for thermodynamic analysis of aircraft engines. The work potential analysis method is implemented in the form of a set of working charts and tables than can be used to graphically evaluate work potential stored in high-enthalpy gas. The range of validity for these charts is 300 to 36,000 °R, pressures between 0.01 and 100 atm, …
The Demise Of Aerospace, Part 2. We Doubt It., John H. Mcmasters, Russell M. Cummings
The Demise Of Aerospace, Part 2. We Doubt It., John H. Mcmasters, Russell M. Cummings
Aerospace Engineering
No abstract provided.
Effects Of Filament Reinforced Plexiglass Pressure Vessel On Failure Analysis, Faysal A. Kolkailah, Eltahry Elghandour, Luis J. Valenzuela
Effects Of Filament Reinforced Plexiglass Pressure Vessel On Failure Analysis, Faysal A. Kolkailah, Eltahry Elghandour, Luis J. Valenzuela
Aerospace Engineering
This paper presents an investigation into the effect of reinforcing a Plexiglas tube with fiberglass/epoxy threads wound at different angles. This paper shows an experimental analysis approach to find the ultimate failure pressure of these vessels. The properties of the Plexiglas, fiberglass, orientation (wind) angle and the matrix were taken into account to determine their effects on the ultimate failure pressure of the vessels. Mandrels were wound at +/- 75, +/- 65, and +/- 55 deg, and specimen were cut out from each to 19.05 cm long, 7.62 cm inner diameter and outer diameters dependent of the wind angle. The …
The Study Of Empirical Methodology To Observe Damping Characteristics Of Various Laminate Composite Plates, Faysal A. Kolkailah, Eltahry Elghandour, Taikha Oh, Jason Bolosan
The Study Of Empirical Methodology To Observe Damping Characteristics Of Various Laminate Composite Plates, Faysal A. Kolkailah, Eltahry Elghandour, Taikha Oh, Jason Bolosan
Aerospace Engineering
Modifying the stiffness of the structure is usually not a feasible solution to enhancing damping, since changing the stiffiless effects the natural frequency changing and eventually the condition of resonance will be reached. Therefore, one of the recommendatory ways to reduce the response on structural elements is to improve damping characteristics. The objectives of this study are to present empirical methodology to detect damping characteristics of structural elements, and determine the optimal location of sensor to detect structural failure by analyzed data from both experimental and numerical analysis. Using orthotropic composite plates comprised of 977-2 Carbon fiber/IM7 epoxy, the natural …
Formulation, Realization, And Demonstration Of A Process To Generate Aerodynamic Metamodels For Hypersonic Cruise Vehicle Design, Robert Mcdonald, D.N. Mavris
Formulation, Realization, And Demonstration Of A Process To Generate Aerodynamic Metamodels For Hypersonic Cruise Vehicle Design, Robert Mcdonald, D.N. Mavris
Aerospace Engineering
The desire to facilitate the conceptual and preliminary design of hypersonic cruise vehicles has created the need for simple, fast, versatile, and trusted aerodynamic analysis tools. Metamodels representing physics-based engineering codes provide instantaneous access to calibrated tools. Nonlinear transformations extend the capability of metamodels to accurately represent a large design space. Independence, superposition, and scaling properties of the hypersonic engineering method afford an expansive design space without traditional compounding penalties. This one-time investment results in aerodynamic and volumetric metamodels of superior quality and versatility which may be used in many forms throughout early design. As a module, they can be …
Supersonic Channel Airfoils For Reduced Drag, Stephen M. Ruffin, Anurag Gupta, David D. Marshall
Supersonic Channel Airfoils For Reduced Drag, Stephen M. Ruffin, Anurag Gupta, David D. Marshall
Aerospace Engineering
A proof-of-concept study is performed for a supersonic channel-airfoil concept,which can be applied to the leading edges of wings, tails, fins, struts, and other appendages of aircraft, atmospheric entry vehicles, and missiles in supersonic flight. It is designed to be beneficial at conditions in which the leading edge is significantly blunted and the Mach number normal to the leading edge is supersonic.The supersonic channel-airfoil concept is found to result in significantly reduced wave drag and total drag (including skin-friction drag) and significantly increased lift/drag although maximum heat-transfer rate was increased for the geometries tested.
Mixed Mode Stable Crack Extensions Through Stiffened Specimens, Abdel-Hamid I. Mourad, Eltahry Elghandour, Faysal A. Kolkailah
Mixed Mode Stable Crack Extensions Through Stiffened Specimens, Abdel-Hamid I. Mourad, Eltahry Elghandour, Faysal A. Kolkailah
Aerospace Engineering
This study presents an experimental investigation of fracture mechanics for isotropic material, aluminum alloy D16AT. The problem of stable crack growth (SCG) has been addressed in this paper. Experimental results are presented for symmetrically stiffened and unstiffened three point bend specimens subjected to different modes, mode I and mixed mode. The stiffeners are doubly bonded to the fatigue pre-cracked specimens parallel to the length at a certain distance behind the crack tip using an adhesive Redux 410 NA. Results concerning load displacement variation, growth of plastic zones, instantaneous crack edge profiles, and tunneling are presented. There is evidence that the …
Sensors Location Effect On The Dynamic Behaviour Of The Composite Structure With Flaw Detection, Eltahry Elghandour, Faysal Kolkailah, Abdel- Hamid I. Mourad
Sensors Location Effect On The Dynamic Behaviour Of The Composite Structure With Flaw Detection, Eltahry Elghandour, Faysal Kolkailah, Abdel- Hamid I. Mourad
Aerospace Engineering
In this paper presents an experimental and numerical investigation ofthe natural frequency of composite material cantilever plates. The stacking sequence of tbe composite plate is Quasi-isotropic laminated plate is [2(0j/±45°/2(90°)]" The plate was subjected to incremental cuts and tests to determine changes in new modal properties. The study included white noise and sinusoidal dynamic testing techniques and a virtual instrument dynamic analyzer. In this study also, determining the resonant frequencies of the undamaged and damaged plate, and evaluating the capabilities of piezoelectric ceramics (PZT's) for fault detection based on their sensitivity and accuracy changes in modal parameters. Numerical results are …
Location Effects Of Passive Damping Material In Cross-Ply Laminates On Natural Frequency And Mode Shape, E. I. Elghandour, F. A. Kolkailah
Location Effects Of Passive Damping Material In Cross-Ply Laminates On Natural Frequency And Mode Shape, E. I. Elghandour, F. A. Kolkailah
Aerospace Engineering
This study presents an experimental investigation of the free vibration of cantilevered composite laminated plates with embedded passive damping material at different stages. A total of five composite laminated plates are considered. The lay-up sequences for the five composite laminated plates with and without two embedded layers of passive damping material are [90°/0°/90°/0°]s, [90°/0°/90°/0°/d]s, [90°/0°/90°/d/0°]s, [90°/0°/d/90°/0°]s, and [90°/d/0°/90°/0°]s. The passive damping material employed is a 3M material, SJ-2015 ISD 112, with peak damping properties in the ambient temperature range of 32°F to 140°F. The composite material used is a carbon …
Navier-Stokes Analysis Of Lift-Enhancing Tabs On Multi-Element Airfoils, Paul G. Carrannanto, Bruce L. Storms, James C. Ross, Russell M. Cummings
Navier-Stokes Analysis Of Lift-Enhancing Tabs On Multi-Element Airfoils, Paul G. Carrannanto, Bruce L. Storms, James C. Ross, Russell M. Cummings
Aerospace Engineering
The flow over multi-element airfoils with flat-plate lift-enhancing tabs was numerically investigated. Tabs ranging in height from 0.25 to 1.25% of the reference airfoil chord were studied near the trailing edge of the main element. The two-dimensional numerical simulation employed an incompressible Navier–Stokes solver using a structured, embedded grid topology. The effects of various tabs were studied at a constant Reynolds number on a two-element airfoil with a slotted flap. Both computed and measured results indicated that a tab in the main-element cove improved the maximum lift and lift-to-drag ratio relative to the baseline airfoil without a tab. Computed streamlines …
Numerical Investigation Of An Airfoil With A Gurney Flap, Cory S. Jang, James C. Ross, Russell M. Cummings
Numerical Investigation Of An Airfoil With A Gurney Flap, Cory S. Jang, James C. Ross, Russell M. Cummings
Aerospace Engineering
A two-dimensional numerical investigation was performed to determine the effect of a Gurney flap on a NACA 4412 airfoil. A Gurney flap is a flat plate on the order of 1–3% of the airfoil chord in length, oriented perpendicular to the chord line and located on the airfoil windward side at the trailing edge. The flowfield around the airfoil was numerically predicted using INS2D, an incompressible Navier–Stokes solver, and the one-equation turbulence model of Baldwin and Barth. Gurney flap sizes of 0.5%, 1.0%, 1.25%, 1.5%, 2.0%, and 3.0% of the airfoil chord were studied. Computational results were compared with available …
Determination Of Drag From Three-Dimensional Viscous And Inviscid Flowfield Computations, David L. Hunt, Russell M. Cummings, M. B. Giles
Determination Of Drag From Three-Dimensional Viscous And Inviscid Flowfield Computations, David L. Hunt, Russell M. Cummings, M. B. Giles
Aerospace Engineering
A momentum balance approach is used to extract the drag from flowfield computations for wings and wing/bodies in subsonic/transonic flight. The drag is decomposed into vorticity, entropy, and enthalpy components which can be related to the established engineering concepts of induced drag, wave and profile drag, and engine power and efficiency. This decomposition of the drag is useful in formulating techniques for accurately evaluating drag using computational fluid dynamics calculations or experimental data. A formulation for reducing the size of the region of the crossflow plane required for calculating the drag is developed using cut-off parameters for viscosity and entropy. …
Integrating Multidisciplinary Design In An Undergraduate Curriculum, Russell M. Cummings, H. Jo Anne Freeman
Integrating Multidisciplinary Design In An Undergraduate Curriculum, Russell M. Cummings, H. Jo Anne Freeman
Aerospace Engineering
Multidisciplinary design and analysis has become the normal mode of operation within most aerospace companies, but the impact of these changes have largely not been reflected at many universities. In an effort to determine if the emergence of multidisciplinary design concepts should influence engineering curricula, NASA has asked several universities (Virginia Tech, Georgia Tech, Clemson, BYU, and Cal Poly) to investigate the practicality of introducing the concepts within their undergraduate curricula. A multidisciplinary team of faculty, students, and industry partners evaluated the aeronautical engineering curriculum at Cal Poly. A variety of ways were found to introduce multidisciplinary themes into the …
Analysis Of The Elements Of Drag In Three-Dimensional Viscous And Inviscid Flows, Russell M. Cummings, M. B. Giles, G. N. Shrinivas
Analysis Of The Elements Of Drag In Three-Dimensional Viscous And Inviscid Flows, Russell M. Cummings, M. B. Giles, G. N. Shrinivas
Aerospace Engineering
This paper examines the analytical, experimental, and computational aspects of tlie determination of the drag acting on an aircraft in flight, with or without powered engines, for subsonic/transonic flow. Using a momentum approach, the drag is represented by an integral over a cross-flow plane at an arbitrary distance behind the aircraft Asymptotic evaluation of tlie integral shows tlie drag can be decomposed into three components corresponding to streamwise vorticity and variations in entropy and stagnation enthalpy. These are shown to be related to tlie established engineering concepts of induced drag, wave drag, profile drag and engine power and efficiency. This …
Supersonic, Turbulent Flow Computation And Drag Optimization For Axisymmetric Afterbodies, Russell M. Cummings, H. T. Yang, Y. H. Oh
Supersonic, Turbulent Flow Computation And Drag Optimization For Axisymmetric Afterbodies, Russell M. Cummings, H. T. Yang, Y. H. Oh
Aerospace Engineering
The compressible, turbulent flow about an axisymmetric body was numerically studied using the MacCormack unsplit explicit algorithm applied to the mass-average Navier-Stokes equations solved in conjunction with the k-ε turbulence model of Jones and Launder. Numerical predictions of total body drag (pressure drag, skin friction drag, and base drag) were made for an axisymmetric body six diameters in length, with and without a boattail. Surface pressures and viscous layer profiles are compared with available wind tunnel data and are found to be in good agreement for both geometries. The Golden Section optimization method was used to optimize the body …