ALBERT

Notes: The preparation of skeletal catalysts is considered, with particular reference to the preparation of skeletal nickel and skeletal copper. Skeletal catalysts have physical properties that are highly desired for some industrial processes, and the means of controlling these properties to optimize performance is reviewed. The preparation can be affected by the initial alloy composition, the quenching process, the leaching procedure, aging and by the addition of promoters. These processes may affect either or both the chemical and physical characteristics of the catalysts. Preparation procedures need to be adjusted for individual reactions if optimal performance is required. The effect of the preparation conditions on the structure and catalytic performance of these systems is reviewed.

Notes: We review here the theory of the early stages of oxidation of the (110) surface of Ni1x Alx, based on ab initio calculations using a plane-wave pseudopotential method. The clean surface and several oxidized surfaces have been investigated, with oxygen coverages up to 2ML of oxygen (1ML = 3 O atoms per 2 surface Al atoms). The theory to date is a description in terms of equilibrium thermodynamics, with a comparison of the free energies of several surfaces of different composition, implemented at the atomic scale. Three environmental parameters are singled out as control variables in this treatment, namely the alloy composition x (assumed to be near 0.5), the temperature T and the partial pressure of oxygen pO2. With certain reasonable approximations an analytic formula for the surface energy ?? is derived in terms of these variables and some constants that are calculated ab initio together with others that are derived from experimental thermodynamic tables. At oxygen pressures just above the threshold for bulk oxidation of NiAl, the calculations explain the observed formation of a thin film of alumina in place of NiAl surface layers, with the consequent dissolution of Ni into the bulk. Ab initio calculations illustrate how the energetics of supplying Al to the surface depends on bulk stoichiometry, which alters the relative stability of different surface oxidation states so as to favour oxidation more if the alloy is Al-rich than if it is Ni-rich.

Notes: There is a pressing need for cleaner fuels (free or aromatics and of minimal sulfur content) or ones that convert chemical energy directly to electricity, silently and without production of noxious oxides and particulates; chemical, petrochemical and pharmaceutical processes that may be conducted in a one-step, solvent-free manner and that use air as the preferred oxidant; and industrial processes that minimize consumption of energy, production of waste, or the use of corrosive, explosive, volatile, and nonbiodegradable materials. All these needs and other desiderata, such as the in situ production and containment of aggressive and hazardous reagents, and the avoidance of use of ecologically harmful elements, may be achieved by designing the appropriate heterogeneous inorganic catalyst, which ideally should be cheap, readily preparable and fully characterizable, preferably under in situ reaction conditions. A range of nanoporous and nanoparticle catalysts that meet most of the stringent demands of sustainable development and responsible (clean) technology is described. Specific examples that are highlighted include the production of adipic acid (precursor of polyamides and urethanes) without the use of concentrated nitric acid nor the production of greenhouse gases such as nitrous oxide; the production of caprolactam (precursor of nylon) without the use of oleum and hydroxylamine sulfate; and the terminal oxyfunctionalization of linear alkanes in air. The topic of biocatalysis and sustainable development is also briefly discussed for the epoxidation of terpenes and fatty acid methyl esters; for the generation of polymers, polylactides, and polyesters; and for the production of 1,3-propanediol from corn.

Notes: This review covers the synthesis, characterization, and physico-chemical properties of microporous and mesoporous aluminophosphates and silicoaluminophosphates molecular sieves. Particular emphasis is given to the materials that have found applications as acid catalysts. We consider the evolution of the synthesis procedures from the first discoveries to the current methodologies and give perspectives for new possible synthesis strategies. Emphasis is given to the use of specially prepared precursors/reactants designed for the use as molecular sieves. Experimental (especially MAS-NMR and FTIR spectroscopy) and theoretical approaches to the description of the Si insertion into the ALPO framework and to the acidic properties of SAPOs and MeAPSOs materials are discussed.

Notes: The diffusion-multiple approachĐ??the creation of composition gradients and intermetallic phases by long-term annealing of junctions of three or more phases/alloysĐ??enables the generation of a large number of phases and compositions for efficient mapping of phase diagrams, phase properties, and kinetics. With an efficiency much higher than that of a conventional approach, many critical materials data, which otherwise would be too time-consuming and expensive to acquire, can be obtained and employed to accelerate alloy design. The critical data for structural materials design include phase diagrams, diffusion coefficients, precipitation kinetics, solution-strengthening effects, and precipitation-strengthening effects. All these data can be obtained from diffusion multiples. The combination of the diffusion-multiple approach with the CALPHAD approach can impact computational design of structural materials. The diffusion-multiple approach can also be applied to combinatorial screening of functional materials having unique physical, chemical, or other properties when micro-scale measurement techniques are available for these properties. Examples are shown to illustrate the progress made to date on applying the diffusion-multiple approach to accelerated design/discovery of materials.

Notes: Renewable energy resources, of which wind energy is prominent, are part of the solution to the global energy problem. Wind turbine and the rotorblade concepts are reviewed, and loadings by wind and gravity as important factors for the fatigue performance of the materials are considered. Wood and composites are discussed as candidates for rotorblades. The fibers and matrices for composites are described, and their high stiffness, low density, and good fatigue performance are emphasized. Manufacturing technologies for composites are presented and evaluated with respect to advantages, problems, and industrial potential. The important technologies of today are prepreg (pre-impregnated) technology and resin infusion technology. The mechanical properties of fiber composite materials are discussed, with a focus on fatigue performance. Damage and materials degradation during fatigue are described. Testing procedures for documentation of properties are reviewed, and fatigue loading histories are discussed, together with methods for data handling and statistical analysis of (large) amounts of test data. Future challenges for materials in the field of wind turbines are presented, with a focus on thermoplastic composites, new structural materials concepts, new structural design aspects, structural health monitoring, and the coming trends and markets for wind energy.

Notes: This review illustrates how catalytically active molecular structures are created on oxide surfaces by attachment of metal complexes with subsequent structural transformation and molecular imprinting on the surfaces. Also discussed is how the designed surfaces are characterized in situ by physical techniques including conventional and time-resolved X-ray absorption fine structure. The structural transformation and molecular imprinting for attached metal complexes can provide a new class of catalytic materials with a high complexity for selective catalysis including shape-selective and asymmetric catalysis.

Notes: This paper describes the use of extended X-ray absorption fine structure spectroscopy (EXAFS) to examine the structure of molten salts and ionic liquids and species dissolved in them. The EXAFS theory is briefly described as are the methods by which EXAFS of these systems can be studied. A range of applications have used EXAFS to investigate the structure of metallic species in ionic liquids from extraction studies to catalysts. The area of structural investigations of ionic liquids is still being developed, although growing rapidly, whereas the structure of molten salts has been studied using EXAFS in more detail.

Notes: In the nanoscience era, the properties of many exciting new materials and devices will depend on the details of their composition down to the level of single atoms. Thus the characterization of the structure and electronic properties of matter at the atomic scale is becoming ever more vital for economic and technological as well as for scientific reasons. The combination of atomic-resolution Z-contrast scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) represents a powerful method to link the atomic and electronic structure to macroscopic properties, allowing materials, nanoscale systems, and interfaces to be probed in unprecedented detail. Z-contrast STEM uses electrons that have been scattered to large angles for imaging. The relative intensity of each atomic column is roughly proportional to Z2, where Z is the atomic number. Recent developments in correcting the aberrations of the lenses in the electron microscope have pushed the achievable spatial resolution and the sensitivity for imaging and spectroscopy in the STEM into the sub-A??ngstrom (sub-A??) regime, providing a new level of insight into the structure/property relations of complex materials. Images acquired with an aberration-corrected instrument show greatly improved contrast. The signal-to-noise ratio is sufficiently high to allow sensitivity even to single atoms in both imaging and spectroscopy. This is a key achievement because the detection and measurement of the response of individual atoms has become a challenging issue to provide new insight into many fields, such as catalysis, ceramic materials, complex oxide interfaces, or grain boundaries. In this article, the state-of-the-art for the characterization of all of these different types of materials by means of aberration-corrected STEM and EELS are reviewed.

Notes: The objective of this review is to critically assess the different approaches developed in recent years to understand the dynamics of open flows such as mixing layers, jets, wakes, separation bubbles, boundary layers, and so on. These complex flows develop in extended domains in which fluid particles are continuously advected downstream. They behave either as noise amplifiers or as oscillators, both of which exhibit strong nonlinearities ( Huerre & Monkewitz 1990 ). The local approach is inherently weakly nonparallel and it assumes that the basic flow varies on a long length scale compared to the wavelength of the instability waves. The dynamics of the flow is then considered as a superposition of linear or nonlinear instability waves that, at leading order, behave at each streamwise station as if the flow were homogeneous in the streamwise direction. In the fully global context, the basic flow and the instabilities do not have to be characterized by widely separated length scales, and the dynamics is then viewed as the result of the interactions between Global modes living in the entire physical domain with the streamwise direction as an eigendirection. This second approach is more and more resorted to as a result of increased computational capability. The earlier review of Huerre & Monkewitz (1990) emphasized how local linear theory can account for the noise amplifier behavior as well as for the onset of a Global mode. The present survey first adopts the opposite point of view by demonstrating how fully global theory accounts for the noise amplifier behavior of open flows. From such a perspective, there is strong emphasis on the very peculiar nonorthogonality of linear Global modes, which in turn allows a novel interpretation of recent numerical simulations and experimental observations. The nonorthogonality of linear Global modes also imposes severe constraints on the extension of linear global theory to the fully nonlinear re??gime. When the flow is weakly nonparallel, this limitation is so severe that the linear Global mode theory is of little help. It is then much more appropriate to develop a fully nonlinear formulation involving the presence of a front separating the base state region from the bifurcated state region.

Notes: We review the fluid mechanics and rheology of dense suspensions, emphasizing investigations of microstructure and total stress. "Dense" or "highly concentrated" suspensions are those in which the average particle separation distance is less than the particle radius. For these suspensions, multiple-body interactions as well as two-body lubrication play a significant role and the rheology is non-Newtonian. We include investigations of multimodal suspensions, but not those of suspensions with dominant nonhydrodynamic interactions. We consider results from both physical experiments and computer simulations and explore scaling theories and the development of constitutive equations.

Notes: George Gabriel Stokes died just over 100 years ago, and it has been more than 150 years since he published his great 1847 paper on water waves. The work of Stokes' precursors, which informed his early publications of 1842Đ??50, is described in the previous volume of the Annual Review of Fluid Mechanics ( Craik 2004 ). Here I examine Stokes' papers and letters concerning water waves.

Notes: Chaotic advection and, more generally, ideas from dynamical systems, have been fruitfully applied to a diverse, and varied, collection of mixing and transport problems arising in engineering applications over the past 20 years. Indeed, the "dynamical systems approach" was developed, and tested, to the point where it can now be considered a standard tool for understanding mixing and transport issues in many disciplines. This success for engineering-type flows motivated an effort to apply this approach to transport and mixing problems in geophysical flows. However, there are fundamental difficulties arising in this endeavor that must be properly understood and overcome. Central to this approach is that the starting point for analysis is a velocity field (i.e., the "dynamical system"). In many engineering applications this can be obtained sufficiently accurately, either analytically or computationally, so that it describes particle trajectories for the actual flow. However, in geophysical flows (and we concentrate here almost exclusively on oceanographic flows), the wide range of dynamically significant time and length scales makes the justification of any velocity field, in the sense of reproducing particle trajectories for the actual flow, a much more difficult matter. Nevertheless, the case for this approach is compelling due to the advances in observational capabilities in oceanography (e.g., drifter deployments, remote sensing capabilities, satellite imagery, etc.), which reveal space-time structures that are highly suggestive of the structures one visualizes in the global, geometrical study of dynamical systems theory. This has been pursued in recent years through a combination of laboratory studies, kinematic models, and dynamically consistent models that have all been compared with observational data. During the course of these studies it has become apparent that a new type of dynamical system is necessary to consider in these studies (i.e., a finite time, aperiodically time-dependent velocity field defined as a data set), which requires the development of new analytical and computational tools, as well as the necessity to discard some of the standard ideas and results from dynamical systems theory. In this article we review a number of the key developments to date in this young, but rapidly developing, area at the interface between geophysical fluid dynamics and applied and computational mathematics. We also describe the wealth of new directions for research that this approach unlocks.

Notes: Efficiently and accurately solving the equations governing fluid flow in oil reservoirs is very challenging because of the complex geological environment and the intricate properties of crude oil and gas at high pressure. We present these challenges and review successful and promising solution approaches. We discuss in detail the modeling of fluid flow in reservoirs with strongly varying rock properties. This requires subgrid-scale models that accurately represent the flow physics due to fine-scale fluctuations. A second focus is on the complex multiphase, multicomponent systems that describe miscible gas injection processes for enhanced oil recovery and CO2 sequestration.

Notes: It has recently become possible to measure the anisotropic distribution of interfaces in polycrystals and composites. Because classical theories for grain growth and coarsening assume isotropic interface properties, they are incapable of explaining how these distributions arise. The purpose of this paper is to review the results of recent experiments, simulations, and theories that document the effects of anisotropy on the capillarity-driven evolution of granular systems. The results suggest that meaningful predictions of evolving microstructural characteristics can be made using models that incorporate the anisotropy of the interfacial energy and mobility.

Notes: This review is an introduction to the problem of determining the nature of the diffraction spectra of ordered solids. After explicit computation examples of Bragg diffraction spectra of quasicrystals (bulk, surface) in kinematical and dynamical (high-resolution electron microscopy) situations, we show on simple toy models that long-range order does not necessarily lead to Bragg peaks which, in turn, are not necessarily the signature of the unique long-range periodic order.

Notes: Recent research trends of the preparation and characterization of highly efficient titanium oxideĐ??based photocatalysts are reviewed on the basis of studies done in our laboratory. Special attention is focused on the preparation and characterization of active sites of highly dispersed titanium oxide species within mesoporous matrices and on titanium oxideĐ??based binary catalysts such as Ti/Si and Ti/B oxides and unique visible light-responsive second-generation TiO2 photocatalysts prepared by an advanced metal-ion-implantation and RF magnetron sputtering deposition method. Highly dispersed titanium oxide species within mesoporous frameworks and titanium oxideĐ??based binary catalysts exhibit high and unique photocatalytic activities for various reactions, such as the direct decomposition of NOx. These species also have photo-induced superhydrophiric properties. It is of significance that visible light-responsive TiO2 photocatalysts can be applied to the decomposition of NOx in air and the degradation of pollutants in water, as well as to the splitting of water under UV and visible light irradiation.

Notes: Heterogeneous asymmetric catalysis remains a topic of intense research interest because control of enantioselectivity represents one of the major synthetic challenges today. Successful strategies to achieve high enantioselection have been developed using three key approaches: (a) adsorption of chiral modifiers onto an active metal surface, which is found to be particularly effective for enantioselective hydrogenation; (b) covalent tethering of homogeneous catalysts; and (c) electrostatic interaction between a negatively charged framework and a cation. Other approaches have been advocated, e.g., encapsulation, but in general these lead to lower enantioselectivity for these heterogeneous asymmetric systems when compared with the equivalent homogeneous catalyst. This review covers the strategies for achieving high enantioselection as well as recent interesting features concerning confinement effects, the inversion of enantioselectivity, and specific cases in which enantioselection increases with conversion, all being factors that can guide researchers to identifying improved systems.

Notes: The review highlights the state-of-the-art research regarding the application of modern in situ spectroscopic, microscopic, and electrochemical techniques to improve the understanding of the interaction of organic molecules with metal surfaces. We also consider the chemical and electrochemical processes that lead to a de-adhesion of polymers from metal surfaces. Spectroscopic techniques such as surface-enhanced infrared or Raman spectroscopy provide molecular understanding of organic molecules and water at buried metal surfaces. This information is complementary to adhesion studies by means of atomic force microscopy and de-adhesion studies of polymer layers from metals by means of a scanning Kelvin probe. Adhesion and de-adhesion mechanisms are discussed, especially those involving humid and corrosive environments, which are the predominant and most important for metal/polymer composites in engineering applications.

Notes: Chemical analysis at high spatial resolution is the domain of analytical transmission electron microscopy. Owing to rapid instrumental developments during the past decade, electron energy-loss spectroscopy offers now a spatial resolution close to 0.1 nm and an energy resolution close to 0.1 eV. This development has been accompanied by the introduction of numerous new techniques and methods for data acquisition and analysis, which are outlined in the present article. Recent results for a wide range of material systems are addressed. These comprise first-principles calculations, which have contributed to enormous progress in the calculation of near-edge fine structures, and fingerprinting methods, which are still important for the interpretation of experimental data.

Notes: Early work and recent advances in feedback control of combustion oscillations are described. The physics of combustion oscillations, most commonly caused by a coupling between acoustic waves and unsteady heat release, are discussed, and the concept of using feedback control to interrupt these interactions is introduced. Factors affecting practical implementation of feedback control, including sensors, actuators, and controller design are described, and the historical development of control strategy for combustion oscillations is reviewed. Finally, demonstrations of feedback control on full-scale combustion systems are described, and it is concluded that there is potential to apply more systematic controller designs at full scale.

Notes: Flow simulations are one of the archetypal multiscale problems. Simulations of turbulent and unsteady separated flows have to resolve a multitude of interacting scales, whereas molecular phenomena determine the structure of shocks and the validity of the no-slip boundary condition. Particle simulations of continuum and molecular phenomena can be formulated by following the motion of interacting particles that carry the physical properties of the flow. In this article we review Lagrangian, multiresolution, particle methods such as vortex methods and smooth particle hydrodynamics for the simulation of continuous flows and molecular dynamics for the simulation of flows at the atomistic scale. We review hybrid molecular-continuum simulations with an emphasis on the computational aspects of the problem. We identify the common computational characteristics of particle methods and discuss their properties that enable the formulation of a systematic framework for multiscale flow simulations.

Notes: Gravity-driven bubbly flows are a specific class of flows, where all action is provided by gravity. An industrial example is formed by the so-called bubble column: a vertical cylinder filled with liquid through which bubbles flow that are introduced at the bottom of the cylinder. On the bubble scale, gravity gives rise to buoyancy of individual bubbles. On larger scales, gravity acts on nonuniformities in the spatial bubble distribution present in the bubbly mixture. The gravity-induced flow and flow structures can increase the inhomogeneity of the bubble distribution, leading to a turbulent flow. In this flow, specific scales are identified: a large-scale circulation with the liquid flowing upward in the center of the column and downward close to the wall. On the intermediate scale there are vortical structures; eddies of liquid, with a size on the order of the diameter of the column, that stir the liquid and radially transport the bubbles. On the small scale there is the local stirring of the bubbles. We describe the ideas developed over time and identify some open questions. We discuss the experimental findings on the turbulence generated, the stability of the flow, axial dispersion, and the similarities between bubble columns and air lifts. Especially for higher gas fractions, many questions still lack accurate answers. The lateral lift force in bubble swarms and the structure of the turbulence in the bubbly mixture are important examples of inadequately understood physical phenomena, providing many challenges for fundamental and applied research on bubbly flows.

Notes: Development and optimization of multifunctional devices for fluidic manipulation of films, drops, and bubbles require detailed understanding of interfacial phenomena and microhydrodynamic flows. Systems are distinguished by a large surface to volume ratio and flow at small Reynolds, capillary, and Bond numbers are strongly influenced by boundary effects and therefore amenable to control by a variety of surface treatments and surface forces. We review the principles underlying common techniques for actuation of droplets and films on homogeneous, chemically patterned, and topologically textured surfaces by modulation of normal or shear stresses.

Notes: "What force does an insect wing generate?" Finding answers to this enduring question is an essential step toward our understanding of interactions of moving objects with fluids that enable most living species such as insects, birds, and fish to travel efficiently and us to follow similar suit with sails, oars, and airfoils. We give a brief history of research in insect flight and discuss recent findings in unsteady aerodynamics of flapping flight at intermediate range Reynolds numbers ( 10Đ??104 ). In particular, we examine the unsteady mechanisms in uniform and accelerated motions, forward and hovering flight, as well as passive flight of free-falling objects. The results obtained by "taking the insects apart" helped us to resolve previous puzzles about the force estimates in hovering insects, to ellucidate basic mechanisms essential to flapping flight, and to gain insights about the efficieny of flight.

Notes: In recent years substantial progress has been made in the control of the properties of porous materials on the nano-, meso-, and macroscale. The feature of solids can, in favorable cases, be tailored to such an extent that one is justified in using the term engineering of porous catalytic materials. This review highlights recent developments concerning (a) the control of the pore structure of zeolites, (b) the creation of single site type catalysts based on ordered mesoporous oxides, (c) the catalytic potential of porous coordination compounds, and (d) the advances with respect to direct production of desired shapes of porous catalytic materials.

Notes: Catalyst life (with activity and selectivity) is one of the three essential properties of a practical catalyst, both in laboratory and industrial usage. For most catalysts in which the active phase is a metal, high activity requires a high metal surface area. In all cases, for long life, the metal surface area has to be maintained. The various modes of catalyst deactivation leading to loss of metal surface area are described (sintering, poisoning, coking, etc.). The choice of catalyst components for both active metal phases and for support phases is shown to be subject to thermodynamic and kinetic limits. Routes for the preparation of catalysts need to be and can be designed to give not only active, but also stable catalysts. Examples described include copper/zinc catalysts for hydrogenation/dehydrogenation reactions, iron catalysts for ammonia synthesis, nickel catalysts for hydrogenation reactions, automobile exhaust catalysts, and Raney catalysts.

Notes: The key role of electron microscopy in understanding and creating advanced catalyst materials and processes in selective alkane oxidation, environmental control, and alternative energy sources is reviewed. In many technological processes, catalysts are increasingly nanoscale heterogeneous materials. With growing regulatory guidelines requiring efficient and environmentally compatible catalytic processes, it is crucial to have a fundamental understanding of the catalyst nanostructure and modes of operation under reaction conditions to design novel catalysts and processes. The review highlights the pioneering development and applications of atomic resolution in situ-environmental transmission electron microscopy (ETEM) for probing dynamic catalysis directly at the atomic level, high-resolution electron microscopy, and analytical spectroscopic methods in the development of alkane catalyzation, environmental protection, and new energy sources.

Notes: This article reviews our current understanding of the physical mechanisms governing the movement of a tropical cyclone. In a barotropic framework, a tropical cyclone is basically "steered" by the surrounding flow but its movement is modified by the Coriolis force (referred to as the beta effect) and the horizontal vorticity gradient of the surrounding flow. In the presence of vertical wind shear and latent heat release, a tropical cyclone tends to move toward an area with a maximum in the time tendency of potential vorticity, which is mainly contributed by two processes: (a) advection that depends on the structures of the vortex and the environment surrounding the vortex in terms of their flow speed and vorticity gradient (including the beta effect), and (b) heating that results from a coupling between the latent heat released in the clouds and the vertical wind shear.

Notes: The large-scale dynamics of the extratropical stratosphere are reviewed. The role of Rossby waves and vortex dynamics in shaping the winter stratospheric circulation and the dynamics of the longitudinal mean flow are first discussed separately. The important effects of two-way interaction between waves and mean flow are then described, with emphasis on how mechanisms discovered in simple models can be followed through to models that are closer to the real stratosphere. A final topic is the possible effect of the stratosphere on the troposphere, with emphasis on dynamical mechanisms for such an effect.

Notes: The flow in turbomachines is unsteady due to the relative motion of the rows of blades. In the low-pressure turbine, the wakes from the upstream bladerows provide the dominant source of unsteadiness. Because much of the blade-surface boundary-layer flow is laminar, one of the most important consequences of this unsteadiness is the interaction of the wakes with the suction-side boundary layer of a downstream blade. This is important because the blade suctionĐ??side boundary layers are responsible for most of the loss of efficiency and because the combined effects of random (wake turbulence) and periodic disturbances (wake velocity defect and pressure fields) cause the otherwise laminar boundary layer to undergo transition and eventually become turbulent. This article summarizes the process of wake-induced boundary-layer transition in low-pressure turbines and the loss generation processes that result. Particular emphasis is placed on how the effects of wakes may be exploited to control loss generation and how this has enabled successful development of ultra-high-lift low-pressure turbines.

Notes: We review major experimental and theoretical studies on microcirculation and hemorheology, focusing on mechanics of blood flow and the vascular wall. We discuss flow of the blood formed elements [red blood cells (RBCs), white blood cells or leukocytes (WBCs) and platelets] in individual arterioles, capillaries, and venules, and in microvascular networks. We also review mechanical and rheological properties of the formed elements and their interactions with the vascular wall. We discuss short-term and long-term regulation of the microvasculature; the modes of regulation include metabolic, myogenic, and shear-stress-dependent mechanisms as well as vascular adaptation such as angiogenesis and vascular remodeling.

Notes: His contemporaries saw R.T. Jones as one of the notably creative aerodynamicists of the twentieth century. This essay reviews his remarkable life and career, including his years as a farm-country boy, college dropout, and fledgling airplane designer in Missouri, his time as an elevator operator and self-directed student in Washington, D.C., and his long professional career as an aerodynamicist at the Langley and Ames Aeronautical Laboratories and Stanford University. The focus in his career is on his fundamental discovery of the benefits of sweepback for the wings of high-speed airplanes. This includes speculation about his highly intuitive thought processes in arriving at his creative ideas. I also give an account of his work on blood flow and the mechanical heart, his avocational accomplishments as a maker of telescopes and violins, and his philosophical interest in human affairs.