The Role of Eigensolutions in Nonlinear Inverse Cavity-Flow Theory

1988 ◽  
Vol 110 (3) ◽  
pp. 315-324
Author(s):  
B. R. Parkin
Keyword(s):  
Inverse Problem ◽  
Free Surface ◽  
Direct Problem ◽  
Cavity Flow ◽  
Cavitation Number ◽  
The Novel ◽  
Cavity Shape ◽  
Linearized Theory ◽  
Exact Point

The method of Levi Civita is applied to an isolated fully cavitating body at zero cavitation number and adapted to the solution of the inverse problem in which one prescribes the pressure distribution on the wetted surface and then calculates the shape. The novel feature of this work is the finding that the exact theory admits the existence of a “point drag” function or eigensolution. While this fact is of no particular importance in the classical direct problem, we already know from the linearized theory that the eigensolution plays an important role. In the present discussion, the basic properties of the exact “point-drag” solution are explored under the simplest of conditions. In this way, complications which arise from non-zero cavitation numbers, free surface effects, or cascade interactions are avoided. The effects of this simple eigensolution on hydrodynamic forces and cavity shape are discussed. Finally, we give a tentative example of how this eigensolution might be used in the design process.

The Linearized Theory of a Supercavitating Hydrofoil With a Jet Flap

1964 ◽  
Vol 86 (4) ◽  
pp. 851-858 ◽  
Author(s):  
Hung-Ta Ho
Keyword(s):  
Theoretical Analysis ◽  
Momentum Flux ◽  
Vortex Sheet ◽  
Cavity Flow ◽  
Cavitation Number ◽  
Pitching Moment ◽  
Cavity Shape ◽  
Small Deflection ◽  
Small Incidence ◽  
Linearized Theory

A theoretical analysis is carried out for the steady cavity flow about thin hydrofoil sections at small incidence α, at the trailing edge of which a thin jet emerges at a small deflection τ. The flow is assumed to be inviscid and incompressible and the cavitation number is taken to be zero. The jet is assumed so thin that it can be considered as a vortex sheet across which the velocity is discontinuous. For the case of a flat plate, expressions have been obtained for lift, drag, pressure distribution, pitching moment, the jet shape, and the cavity shape. Numerical calculations are made for a number of jet momentum-flux coefficients CJ lying between 0.01 and 5.

Steady Performance of a Flexible Hydrofoil Near a Free Surface

1990 ◽  
Vol 34 (04) ◽  
pp. 302-310
Author(s):  
Salwa M. Rashad ◽  
Theodore Green
Keyword(s):  
Mathematical Model ◽  
Free Surface ◽  
Cavity Length ◽  
Leading Edge ◽  
Cavity Flow ◽  
Cavitation Number ◽  
Deformation Characteristics ◽  
Flow Depth ◽  
Lift And Drag ◽  
The Galerkin Method

A linearized cavity-flow theory is used to develop a mathematical model to study the steady characteristics of a flexible hydrofoil near a free surface. The Galerkin method is employed to account for the mutual interaction between the fluid and structure forces. Cheng and Rott's method [1]2 is used to derive general expressions for the deformation characteristics in steady flow of an arbitrarily shaped hydrofoil, with a clamped trailing edge and free leading edge. From the analysis it is possible to determine the lift and drag coefficients, cavity length, and the foil steady deformation for any given specific foil shape, cavitation number, angle of attack, flow depth/chord ratio and rigidity. Sample numerical results are given, and the effects of flexibility and the proximity of the free surface are discussed. Chordwise flexibility tends to increase drag and decrease lift coefficients. This effect is more serious near the free surface. A slight increase of the thickness near the leading edge diminishes the flexibility effects.

Inverse Methods in the Linearized Theory of Fully Cavitating Hydrofoils

1964 ◽  
Vol 86 (4) ◽  
pp. 641-654 ◽  
Author(s):  
B. R. Parkin ◽  
R. S. Grote
Keyword(s):  
Inverse Problem ◽  
Pressure Distribution ◽  
Cavitation Number ◽  
Inverse Methods ◽  
Two Dimensional ◽  
Physical Constraints ◽  
Two Dimensional Flow ◽  
Linearized Theory ◽  
Profile Design ◽  
Major Emphasis

Theoretical and numerical procedures are given for the design of fully cavitating hydrofoils in a steady two-dimensional flow. The only boundary in the flow is that provided by the hydrofoil and its cavity. The cavity is always assumed to spring from the nose and trailing edge of the profile. The methods used are those of linearized inverse airfoil theory, in which one prescribes the pressure distribution on the wetted surface of the profile and then calculates its shape. The theory at zero cavitation number is considered anew in order to highlight the physical constraints involved in this inverse problem. However, major emphasis is given to basic procedures for profile design at nonzero or zero cavitation numbers. Optimum hydrofoil design is discussed from an engineering viewpoint.

Some Characteristics of Cavity Flow Past Cylindrical Inducers in a Venturi

1976 ◽  
Vol 98 (3) ◽  
pp. 461-466 ◽  
Author(s):  
B. C. Syamala Rao ◽  
D. V. Chandrasekhara
Keyword(s):  
Reynolds Number ◽  
Strouhal Number ◽  
Cavity Flow ◽  
Cavitation Number ◽  
Circular Cylinders ◽  
Two Dimensional ◽  
Wall Effects ◽  
Maximum Width ◽  
Shedding Frequency

The characteristic dimensions of the steady cavity and the shedding frequency of vortices behind six circular cylinders in a two-dimensional venturi have been studied. The normalized length and maximum width of cavity for cavitation sources of different sizes indicated unified trends with a modified cavitation number km. The angles of detachment θ increased with cavitation number k and decreased with increasing Reynolds number R. The Strouhal number Sd reached minimum values for all cavitation sources at small values of k. The possible role of wall effects on the investigations are discussed.

Two-Dimensional, Steady, Cavity Flow About Slender Bodies in Channels of Finite Breadth

1957 ◽  
Vol 24 (2) ◽  
pp. 170-176
Author(s):  
Hirsh Cohen ◽  
Robert Gilbert
Keyword(s):  
Cavity Length ◽  
Solid Wall ◽  
Cavity Flow ◽  
Cavitation Number ◽  
Integral Equation Formulation ◽  
Slender Bodies ◽  
Linearized Theory ◽  
Finite Breadth ◽  
Arbitrary Body ◽  
Cavity Width

Abstract The steady, cavitating flow past slender symmetrical bodies placed in a solid-wall channel is studied by means of the linearized theory of Tulin. The free-boundary condition is linearized and boundary conditions are applied on the line of symmetry of the flow in analogy with thin-air-foil theory. A singular integral equation formulation of the boundary-value problem is obtained and can be solved to yield expressions for cavity length, maximum cavity width, and drag coefficient as functions of the cavitation number and the channel breadth. These expressions are given for an arbitrary body and evaluated for the case of a wedge.

On the role of tin underlays for the prevention of thermal grooving in thin gold films

1986 ◽  
Vol 44 ◽  
pp. 732-733
Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff
Keyword(s):  
Thin Film ◽  
Free Surface ◽  
Grain Boundary ◽  
Beneficial Effect ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Distinct Advantage ◽  
Gold Films ◽  
Gold Thin Film

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.

ROLE OF THE NOVEL INTRODUCED PAN-INTESTINAL CAPSULE ENDOSCOPY SYSTEM IN CELIAC DISEASE

2019 ◽  
Author(s):  
F Foerster ◽  
K Mönkemüller ◽  
PR Galle ◽  
H Neumann
Keyword(s):  
Celiac Disease ◽  
Capsule Endoscopy ◽  
The Novel

Patterns: Rosamond Lehmann

2018 ◽  
Author(s):  
Vike Martina Plock
Keyword(s):  
Coming Of Age ◽  
Public Image ◽  
Market Forces ◽  
The Novel ◽  
Fashion Industry ◽  
To The Lighthouse ◽  
Fashion Magazines ◽  
Female Authorship ◽  
Rosamond Lehmann

This chapter analyzes the role of fashion as a discursive force in Rosamond Lehmann’s 1932 coming-of-age novel Invitation to the Waltz. Reading the novel alongside such fashion magazines as Vogue, it demonstrates Lehmann’s awareness that 1920s fashion, in spite of its carefully stylized public image as harbinger of originality, emphasized the importance of following preconceived (dress) patterns in the successful construction of modern feminine types. Invitation to the Waltz, it argues, opposes the production of patterned types and celebrates difference and disobedience in its stead. At the same time, the novel’s formal appearance is nonetheless dependent on the very same tenets it criticizes. On closer scrutiny, it is seen to reveal its resemblance to Virginia Woolf’s To the Lighthouse (1927). A tension between imitation and originality determines sartorial fashion choices. This chapter shows that female authorship in the inter-war period was subjected to the same market forces that controlled and sustained the organization of the fashion industry.

SARS-COV2 virus and Coronavirus disease (COVID-19)

2020 ◽  
Vol 11 (SPL1) ◽  
pp. 977-982
Author(s):  
Mohamed J. Saadh ◽  
Bashar Haj Rashid M ◽  
Roa’a Matar ◽  
Sajeda Riyad Aldibs ◽  
Hala Sbaih ◽  
...  
Keyword(s):  
Close Contact ◽  
Antiviral Agents ◽  
Health Concern ◽  
The Novel ◽  
Global Public Health ◽  
Fatal Disease ◽  
Mild Disease ◽  
Life Threatening ◽  
Novel Coronavirus

SARS-COV2 virus causes Coronavirus disease (COVID-19) and represents the causative agent of a potentially fatal disease that is of great global public health concern. The novel coronavirus (2019) was discovered in 2019 in Wuhan, the market of the wet animal, China with viral pneumonia cases and is life-threatening. Today, WHO announces COVID-19 outbreak as a pandemic. COVID-19 is likely to be zoonotic. It is transmitted from bats as intermediary animals to human. Also, the virus is transmitted from human to human who is in close contact with others. The computerized tomographic chest scan is usually abnormal even in those with no symptoms or mild disease. Treatment is nearly supportive; the role of antiviral agents is yet to be established. The SARS-COV2 virus spreads faster than its two ancestors, the SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV), but has lower fatality. In this article, we aimed to summarize the transmission, symptoms, pathogenesis, diagnosis, treatment, and vaccine to control the spread of this fatal disease.

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