Ambient Supercavities of Slender Bodies of Revolution

1986 ◽  
Vol 30 (03) ◽  
pp. 215-219
Author(s):  
William S. Vorus
Keyword(s):  
Cavitation Number ◽  
Slender Body ◽  
Surface Velocity ◽  
Body Of Revolution ◽  
Cavity Pressure ◽  
Slender Body Theory ◽  
Bodies Of Revolution ◽  
Specific Analysis ◽  
Slender Bodies ◽  
Body Theory

Slender-body theory is applied in an analysis of the flow about the general supercavitating streamlined body of revolution. The formulation is specialized to the case of ambient cavity pressure (zero cavitation number) for the specific analysis conducted. Numerical procedures are outlined. The methodology is demonstrated in calculating the cavity shapes, surface velocity distributions, and cavity form drag coefficients for three idealized bodies. These are the convex paraboloid, the conical frustrum, and the concave paraboloid. Characteristic differences in the flows in each of the cases are discussed.

A slender-body theory for ship oscillations in waves

1964 ◽  
Vol 18 (4) ◽  
pp. 602-618 ◽  
Author(s):  
J. N. Newman
Keyword(s):  
Slender Body ◽  
Body Of Revolution ◽  
Slender Body Theory ◽  
First Order ◽  
Incident Plane ◽  
Slender Bodies ◽  
Linearized Theory ◽  
Progressive Waves ◽  
Body Potential ◽  
Body Theory

A linearized theory is developed for the oscillations of a slender body which is floating on the free surface of an ideal fluid, in the presence of incident plane progressive waves. Green's theorem is used to represent the velocity potential and the first-order slender-body potential is developed from asymptotic approximation. The general theory is valid for arbitrary slender bodies in oblique waves, and detailed results are presented for a body of revolution.

Calculation of Subsonic Normal Force and Centre of Pressure Position of Bodies of Revolution Using a Slender Body Theory – Boundary Layer Method

1980 ◽  
Vol 31 (1) ◽  
pp. 1-25
Author(s):  
K.D. Thomson
Keyword(s):  
Boundary Layer ◽  
Velocity Distribution ◽  
Normal Force ◽  
The Body ◽  
Slender Body ◽  
Centre Of Pressure ◽  
Slender Body Theory ◽  
Bodies Of Revolution ◽  
Slender Bodies ◽  
Body Theory

SummaryThe aim of this paper is to present a method for predicting the aerodynamic characteristics of slender bodies of revolution at small incidence, under flow conditions such that the boundary layer is turbulent. Firstly a panel method based on slender body theory is developed and used to calculate the surface velocity distribution on the body at zero incidence. Secondly this velocity distribution is used in conjunction with an existing boundary layer estimation method to calculate the growth of boundary layer displacement thickness which is added to the body to produce the effective aerodynamic profile. Finally, recourse is again made to slender body theory to calculate the normal force curve slope and centre of pressure position of the effective aerodynamic profile. Comparisons made between predictions and experiment for a number of slender bodies extending from highly boattailed configurations to ogive-cylinders, and covering a large range of boundary layer growth rates, indicate that the method is useful for missile design purposes.

scholarly journals Dropping slender-body theory into the mud

2019 ◽  
Vol 862 ◽  
pp. 1-4
Author(s):  
S. E. Spagnolie
Keyword(s):  
Fluid Flow ◽  
Aspect Ratio ◽  
Slender Body ◽  
Viscoplastic Fluid ◽  
Slender Body Theory ◽  
Viscous Fluid Flow ◽  
Physical Systems ◽  
Surrounding Environment ◽  
Slender Bodies ◽  
Body Theory

The equations describing classical viscous fluid flow are notoriously challenging to solve, even approximately, when the flow is host to one or many immersed bodies. When an immersed body is slender, the smallness of its aspect ratio can sometimes be used as a basis for a ‘slender-body theory’ describing its interaction with the surrounding environment. If the fluid is complex, however, such theories are generally invalid and efforts to understand the dynamics of immersed bodies are almost entirely numerical in nature. In a valiant effort, Hewitt & Balmforth (J. Fluid Mech., vol. 856, 2018, pp. 870–897) have unearthed a theory to describe the motion of slender bodies in a viscoplastic fluid, ‘fluids’ such as mud or toothpaste which can be coaxed to flow, but only with a sufficiently large amount of forcing. Mathematical theories for some tremendously complicated physical systems may now be within reach.

The Slender Wing with a Half Body of Revolution Mounted Beneath

1968 ◽  
Vol 72 (693) ◽  
pp. 803-807 ◽  
Author(s):  
H. Portnoy
Keyword(s):  
Supersonic Flow ◽  
Slender Body ◽  
Meridian Plane ◽  
Pitching Moment ◽  
Body Of Revolution ◽  
Slender Body Theory ◽  
Lift And Drag ◽  
Body Theory ◽  
Slender Wing

Summary The slender-body theory of Ward is applied to a configuration consisting of a slender, pointed wing, carrying directly beneath it a pointed half-body of revolution divided along a meridian plane. Expressions for lift and drag due to incidence are found which are valid in both subsonic and supersonic flow if the flow is attached. The lift result can be used to find pitching moment. For the supersonic case the drag at zero incidence is also found and the expressions for a conical configuration are developed so that a limiting form of these can be compared with the results of ref. 3.

A Combination of the Quasi-Cylinder and Slender Body Theories

1955 ◽  
Vol 59 (532) ◽  
pp. 305-308 ◽  
Author(s):  
C. H. E. Warren ◽  
L. E. Fraenkel
Keyword(s):  
Point Of View ◽  
The Body ◽  
Slender Body ◽  
Maximum Diameter ◽  
Slender Body Theory ◽  
Bodies Of Revolution ◽  
Pressure Distributions ◽  
Simple Body ◽  
Body Theory ◽  
Supersonic Flow Past Bodies

The Quasi-Cylinder and slender body theories for the supersonic flow past bodies of revolution have been much used in recent years because, for reasonably simple body profiles, these theories permit a simple and rapid calculation of the first-order pressure distributions and aerodynamic forces. It is assumed in both theories that the body profile slope is small; in the quasi-cylinder theory it is also assumed that the body radius is nearly constant, whereas in the slender body theory it is assumed that the thickness ratio of the body (maximum diameter/length) is small.In the present note these two theories are combined completely. From a strictly mathematical point of view nothing is gained by this combination, and, furthermore,application of the combined theory to a particular case is in general a little more laborious than application of either of the original theories.

A Slender-Body Theory in Acoustics

1995 ◽  
Author(s):  
Michel Tran Van Nhieu
Keyword(s):  
Sound Field ◽  
Practical Method ◽  
The Body ◽  
Slender Body ◽  
Slender Body Theory ◽  
New Approach ◽  
Singular Perturbation Methods ◽  
Slender Bodies ◽  
Computation Load ◽  
Body Theory

Abstract A new approach has been proposed to calculate the sound pressure field radiated or scattered from slender bodies. The theoretical analysis is based upon mathematical singular perturbation methods leading to the so-called slender-body approximation. The theory provides a practical method to compute the sound field as it allows a great simplification in the geometrical representation of the body surface and a reduced computation load. This paper summarizes the main results obtained with this approximation at the present state of investigation.

scholarly journals Regularized Stokeslets Lines Suitable for Slender Bodies in Viscous Flow

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 335
Author(s):  
Boan Zhao ◽  
Lyndon Koens
Keyword(s):  
Regularization Parameter ◽  
Near Field ◽  
The Body ◽  
Slender Body ◽  
Slender Body Theory ◽  
Slip Boundary ◽  
Slender Bodies ◽  
Angular Dependency ◽  
Regularized Stokeslets ◽  
Body Theory

Slender-body approximations have been successfully used to explain many phenomena in low-Reynolds number fluid mechanics. These approximations typically use a line of singularity solutions to represent flow. These singularities can be difficult to implement numerically because they diverge at their origin. Hence, people have regularized these singularities to overcome this issue. This regularization blurs the force over a small blob and thereby removing divergent behaviour. However, it is unclear how best to regularize the singularities to minimize errors. In this paper, we investigate if a line of regularized Stokeslets can describe the flow around a slender body. This is achieved by comparing the asymptotic behaviour of the flow from the line of regularized Stokeslets with the results from slender-body theory. We find that the flow far from the body can be captured if the regularization parameter is proportional to the radius of the slender body. This is consistent with what is assumed in numerical simulations and provides a choice for the proportionality constant. However, more stringent requirements must be placed on the regularization blob to capture the near field flow outside a slender body. This inability to replicate the local behaviour indicates that many regularizations cannot satisfy the no-slip boundary conditions on the body’s surface to leading order, with one of the most commonly used blobs showing an angular dependency of velocity along any cross section. This problem can be overcome with compactly supported blobs, and we construct one such example blob, which can be effectively used to simulate the flow around a slender body.

Bundled slender-body theory for elongated geometries in swimming bacteria

2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Bin Liu ◽  
Jeremias Gonzalez
Keyword(s):  
Slender Body ◽  
Slender Body Theory ◽  
Swimming Bacteria ◽  
Body Theory

scholarly journals Hydrodynamic Modeling and Design of Robotic Fish using Slender Body Theory

2021 ◽  
Vol 1012 ◽  
pp. 012007
Author(s):  
Palmani Duraisamy ◽  
Manigandan Nagarajan Santhanakrishnan
Keyword(s):  
Hydrodynamic Modeling ◽  
Robotic Fish ◽  
Slender Body ◽  
Slender Body Theory ◽  
Body Theory
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