Prediction of Transpired Turbulent Boundary Layers

1974 ◽  
Vol 96 (1) ◽  
pp. 89-94 ◽  
Author(s):  
R. H. Pletcher
Keyword(s):  
Compressible Flows ◽  
Length Distribution ◽  
Turbulent Boundary Layers ◽  
Mixing Length ◽  
Law Of The Wall ◽  
Damping Function ◽  
The Past ◽  
Wide Range ◽  
Layer Flow ◽  
New Formulation

A model for the mixing length distribution near the wall in turbulent boundary layer flow with transpiration is presented. The model is based on a new formulation of the exponential damping function originally suggested by Van Driest. The analysis used to evaluate the damping function employs the same set of assumptions successfully used by several investigators in the past to develop the law of the wall with blowing. This mixing length model is then used with the calculation method previously developed by the author to solve the governing conservation equations of mass, momentum, and energy in partial differential form. Predicted velocity profiles, skin friction coefficients, and Stanton numbers are compared with experimental results taken over a wide range of transpiration for both incompressible and compressible flows.

Equilibrium-Turbulent Boundary Layer Prediction for a Proposed Prandtl Mixing Length Distribution

1968 ◽  
Vol 10 (5) ◽  
pp. 426-433 ◽  
Author(s):  
F. C. Lockwood
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Boundary Layers ◽  
Length Distribution ◽  
Momentum Equation ◽  
Turbulent Boundary Layers ◽  
Mixing Length ◽  
Good Agreement

The momentum equation is solved numerically for a suggested ramp variation of the Prandtl mixing length across an equilibrium-turbulent boundary layer. The predictions of several important boundary-layer functions are compared with the equilibrium experimental data. Comparisons are also made with some recent universal recommendations for turbulent boundary layers since the equilibrium experimental data are limited. Good agreement is found between the predictions, the experimental data, and the recommendations.

Compressible Flow Ejectors: Part I—Development of a Finite-Difference Flow Model

1974 ◽  
Vol 96 (3) ◽  
pp. 272-281 ◽  
Author(s):  
K. R. Hedges ◽  
P. G. Hill
Keyword(s):  
Boundary Layer ◽  
Finite Difference ◽  
Initial Conditions ◽  
Length Distribution ◽  
Mixing Length ◽  
Jet Mixing ◽  
Free Jet ◽  
Finite Difference Approximations ◽  
Constant Diameter ◽  
Wide Range

A general method of calculating two-dimensional (plane and axisymmetric) mixing of a compressible jet in variable-area ducts has been developed. The method incorporates finite-difference approximations to the conservation equations, and is applicable to a wide range of Mach number, mass flow ratio, and initial conditions. The model was based on mixing length approximations deduced from boundary-layer and free-jet mixing for the upstream portion of the flow, and on a new mixing length distribution for the downstream zone which is entirely occupied by shear flow. The method has been tested and found satisfactory with existing data on boundary layer, constant-diameter duct entrance flow, constant-pressure jet mixing, and jet mixing in variable-area ducts. Part II of the paper describes tests of the method with new data from an experimental ejector study.

Mixing Length in the Wall Region of Turbulent Boundary Layers

1977 ◽  
Vol 28 (2) ◽  
pp. 97-110 ◽  
Author(s):  
R A McD Galbraith ◽  
S Sjolander ◽  
M R Head
Keyword(s):  
Boundary Layers ◽  
Universal Constant ◽  
Turbulent Boundary Layers ◽  
Wall Region ◽  
Mixing Length ◽  
Law Of The Wall ◽  
Universal Law

SummaryEvidence is presented to show that the universal law of the wall has a wider range of validity than the assumptionl= ky, with k a universal constant. If an effective value of k is defined for the wall region its value is shown to vary between wide limits, and keffcan be correlated with other parameters describing the flow in the wall region.

A law of the wall for compressible turbulent boundary layers with air injection

1969 ◽  
Vol 37 (3) ◽  
pp. 449-456 ◽  
Author(s):  
L. C. Squire
Keyword(s):  
Experimental Data ◽  
Boundary Layers ◽  
Present Report ◽  
Turbulent Boundary Layers ◽  
Air Injection ◽  
Mixing Length ◽  
Law Of The Wall ◽  
Friction Measurements ◽  
Mixing Length Theory ◽  
Considerable Body

A considerable body of experimental data now exists concerning turbulent boundary layers with air injection at the wall, both at subsonic and at supersonic speeds. In the present report these data for Mach numbers up to 6·5 have been analyzed to find the parameters which occur in the law of the wall as deduced from mixing-length theory. Although the absolute values of the parameters are subject to error because of the lack of accurate skin-friction measurements, the trends of these parameters with Mach number and injection mass flow are clearly defined.

Immersogeometric analysis of compressible flows with application to aerodynamic simulation of rotorcraft

2019 ◽  
Vol 29 (05) ◽  
pp. 905-938 ◽  
Author(s):  
Fei Xu ◽  
Yuri Bazilevs ◽  
Ming-Chen Hsu
Keyword(s):  
Compressible Flows ◽  
Benchmark Problems ◽  
Complex Geometries ◽  
High Fidelity ◽  
Engineering Systems ◽  
Flow Simulations ◽  
Wide Range ◽  
Boundary Representations ◽  
New Formulation ◽  
Aerodynamic Simulation

We present an immersogeometric analysis (IMGA) approach for the simulation of compressible flows around complex geometries. In this method, compressible flow simulations are performed directly on various boundary representations (B-reps) of mechanical designs, circumventing the labor-intensive and time-consuming cleanup of complex geometric models. A new formulation for the weak imposition of essential boundary conditions in the context of non-body-fitted meshes is proposed. The formulation employs the non-symmetric Nitsche method, which yields good performance especially when the penalty parameters are difficult to estimate. We test the proposed immersogeometric formulation on benchmark problems for a wide range of Reynolds and Mach numbers, showing its robustness and accuracy. Finally, the methodology is applied to the simulation of a UH-60 Black Hawk helicopter in forward flight, illustrating the ability of the proposed approach to support the design of real-world engineering systems through high-fidelity aerodynamic analysis.

Optical Properties of HVEM Accelerators

1975 ◽  
Vol 33 ◽  
pp. 180-181
Author(s):  
A. Strojnik ◽  
J.W. Scholl ◽  
V. Bevc
Keyword(s):  
Optical Properties ◽  
Electron Accelerator ◽  
Systematic Investigation ◽  
Electron Source ◽  
High Brightness ◽  
The Past ◽  
Wide Range ◽  
Optical Behavior

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).

Pursuit of the Abscopal Effect

2020 ◽  
Vol 04 (04) ◽  
pp. 369-372
Author(s):  
Paul B. Romesser ◽  
Christopher H. Crane
Keyword(s):  
Tumor Immunology ◽  
Antitumor Immunity ◽  
Clinical Success ◽  
Immune Recognition ◽  
Immune Modulators ◽  
Cancer Subtypes ◽  
The Past ◽  
Tumor Irradiation ◽  
Wide Range ◽  
Tumor Recognition

AbstractEvasion of immune recognition is a hallmark of cancer that facilitates tumorigenesis, maintenance, and progression. Systemic immune activation can incite tumor recognition and stimulate potent antitumor responses. While the concept of antitumor immunity is not new, there is renewed interest in tumor immunology given the clinical success of immune modulators in a wide range of cancer subtypes over the past decade. One particularly interesting, yet exceedingly rare phenomenon, is the abscopal response, characterized by a potent systemic antitumor response following localized tumor irradiation presumably attributed to reactivation of antitumor immunity.

The Many Pasts of Detective Fiction

2020 ◽  
Vol 1 (2) ◽  
pp. 157-172
Author(s):  
Thomas Leitch
Keyword(s):  
Detective Fiction ◽  
Golden Age ◽  
Public History ◽  
Detective Novel ◽  
Sherlock Holmes ◽  
Detective Story ◽  
The Past ◽  
Wide Range ◽  
Detective Novels ◽  
The Many

Building on Tzvetan Todorov's observation that the detective novel ‘contains not one but two stories: the story of the crime and the story of the investigation’, this essay argues that detective novels display a remarkably wide range of attitudes toward the several pasts they represent: the pasts of the crime, the community, the criminal, the detective, and public history. It traces a series of defining shifts in these attitudes through the evolution of five distinct subgenres of detective fiction: exploits of a Great Detective like Sherlock Holmes, Golden Age whodunits that pose as intellectual puzzles to be solved, hardboiled stories that invoke a distant past that the present both breaks with and echoes, police procedurals that unfold in an indefinitely extended present, and historical mysteries that nostalgically fetishize the past. It concludes with a brief consideration of genre readers’ own ambivalent phenomenological investment in the past, present, and future each detective story projects.

Nine Centuries of Man

2017 ◽  
Keyword(s):  
Twentieth Century ◽  
Diverse Range ◽  
Gender Expectations ◽  
Court Records ◽  
The Past ◽  
Wide Range ◽  
Police Reports ◽  
Late Twentieth ◽  
Scottish History ◽  
Late Twentieth Century

What did it mean to be a man in Scotland over the past nine centuries? Scotland, with its stereotypes of the kilted warrior and the industrial ‘hard man’, has long been characterised in masculine terms, but there has been little historical exploration of masculinity in a wider context. This interdisciplinary collection examines a diverse range of the multiple and changing forms of masculinities from the late eleventh to the late twentieth century, exploring the ways in which Scottish society through the ages defined expectations for men and their behaviour. How men reacted to those expectations is examined through sources such as documentary materials, medieval seals, romances, poetry, begging letters, police reports and court records, charity records, oral histories and personal correspondence. Focusing upon the wide range of activities and roles undertaken by men – work, fatherhood and play, violence and war, sex and commerce – the book also illustrates the range of masculinities that affected or were internalised by men. Together, the chapters illustrate some of the ways Scotland’s gender expectations have changed over the centuries and how, more generally, masculinities have informed the path of Scottish history

Free but fragile: Human relations amidst poverty and HIV in democratic South Africa

2015 ◽  
Vol 2 (2) ◽  
pp. 85-94
Author(s):  
Christina Landman
Keyword(s):  
South Africa ◽  
Predominantly White ◽  
Black People ◽  
Hiv Treatment ◽  
Human Relations ◽  
White People ◽  
Black And White ◽  
The Past ◽  
Wide Range ◽  
Black Township

Dullstroom-Emnotweni is the highest town in South Africa. Cold and misty, it is situated in the eastern Highveld, halfway between the capital Pretoria/Tswane and the Mozambique border. Alongside the main road of the white town, 27 restaurants provide entertainment to tourists on their way to Mozambique or the Kruger National Park. The inhabitants of the black township, Sakhelwe, are remnants of the Southern Ndebele who have lost their land a century ago in wars against the whites. They are mainly dependent on employment as cleaners and waitresses in the still predominantly white town. Three white people from the white town and three black people from the township have been interviewed on their views whether democracy has brought changes to this society during the past 20 years. Answers cover a wide range of views. Gratitude is expressed that women are now safer and HIV treatment available. However, unemployment and poverty persist in a community that nevertheless shows resilience and feeds on hope. While the first part of this article relates the interviews, the final part identifies from them the discourses that keep the black and white communities from forming a group identity that is based on equality and human dignity as the values of democracy.

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