WorldCat Identities

Saffman, P. G.

Overview
Works: 91 works in 146 publications in 3 languages and 702 library holdings
Genres: Academic theses 
Roles: Author, Thesis advisor
Classifications: QA925, 532.0595
Publication Timeline
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Most widely held works about P. G Saffman
 
Most widely held works by P. G Saffman
Vortex dynamics by P. G Saffman( Book )

39 editions published between 1992 and 2001 in 3 languages and held by 543 WorldCat member libraries worldwide

The discovery of coherent structures in turbulence has fostered the hope that the study of vortices will lead to models and an understanding of turbulent flow, thereby solving or at least making less mysterious one of the great unresolved problems of classical physics. Vortex dynamics is a natural paradigm for the field of chaotic motion and modern dynamical system theory. The emphasis in this monograph is on the classical theory of inviscid incompressible fluids containing finite regions of vorticity. The effects of viscosity, compressibility, inhomogeneity, and stratification are enormously important in many fields of application, from hypersonic flight to global environmental fluid mechanics. However, this volume focuses on those aspects of fluid motion that are primarily controlled by the vorticity and are such that the effects of the other fluid properties are secondary. This book will be of interest to students of fluid mechanics, turbulence, and vortex methods as well as to applied mathematicians and engineers
An application of the Wiener-Hermite expansion to the diffusion of a passive scalar in a homogeneous turbulent flow by P. G Saffman( Book )

4 editions published between 1967 and 1968 in English and held by 21 WorldCat member libraries worldwide

The report describes the application of a truncated Wiener-Hermite expansion of the velocity and concentration fields to analyze (1) the diffusion and mixing of a passive scalar from a point source in a turbulent fluid, and (2) the spectrum and intensity decay of a homogeneous distribution in an approximately homogeneous flow. The problem has important practical applications in reentry physics and air and water pollution. The truncated Wiener-Hermite expansion is treated as an approximation to the velocity field that must satisfy the Navier-Stokes equations; it is truncated at the first stage that gives nontrivial results. The mean concentration from a point source is shown to satisfy an integro-differential equation with diffusive and wavelike properties. The effective diffusivity is determined in terms of Eulerian velocity coordinates. For the homogeneous case, the concentration spectrum equals the energy spectrum times the mean-square concentration divided by the mean-square velocity component. A modification of Batchelor's theory is combined with this equation to predict the decay rate
Research in Nonlinear Water Waves( Book )

8 editions published between 1989 and 1991 in English and held by 5 WorldCat member libraries worldwide

The major effort has been work on the calculation of wind drift effects on the properties of finite amplitude capillary gravity waves. The code is extended to the case when the wave is not too steep and the wind drift layer is thin compared with the height of the wave. Results have been obtained showing the effect of the wind drift layer on the properties of finite amplitude waves of permanent form. These are currently being validated to compare with the theory of Banner & Phillips which models the wind drift layer by a quasi-one-dimensional sheet. The construction of a boundary integral type code is being evaluated which will enable the calculation of the effect of the wind drift layer on steep waves. A remarkable result is the stability of the waves when there is a wind drift layer. It appears that infinitesimal waves may be spontaneously unstable in the presence of a thin drift layer of sufficient strength. First results indicate that capillary gravity waves in a narrow band of around 2 cm wavelength are unstable for a wind drift layer corresponding to a wind speed of around 15 knots. This appears to be a complete new mechanism for the generation of waves by wind, since it is independent of the air motion once the wind drift layer is set up by viscous or turbulent stresses. (jhd)
The motion of a vortex filament with axial flow by D. W Moore( Book )

2 editions published in 1972 in English and held by 3 WorldCat member libraries worldwide

The Stability of Inviscid Vortex Streets of Finite Cored Vortices by Mathematics Research Center (United States. Army)( Book )

3 editions published in 1984 in English and held by 2 WorldCat member libraries worldwide

The stability of two-dimensional infinitesimal disturbances of the inviscid Karman vortex street of finite area vortices is reexamined. Numerical results are obtained for the growth rate and oscillation frequencies of disturbances of arbitrary subharmonic wavenumber and the stability boundaries are calculated. The stabilization of the pairing instability by finite area demonstrated by Staffman and Schatzman (1982) is confirmed and also Kida's (1982) result that this is not the most unstable disturbance when the area is finite. Contrary, however, to Kida's quantitative predictions, it is now found that finite area does not stabilize the street to infinitesimal two-dimensional disturbances of arbitrary wavelength and that it is always unstable except for one isolated value of the aspect ratio which depends upon the size of the vortices. (Author)
A spherical vortex model for homogeneous turbulence by Keri A Aivazis( Book )

1 edition published in 1999 in English and held by 2 WorldCat member libraries worldwide

Saffman-Taylor fingers in deformed Hele-Shaw cells /cDonal A. Gallagher ; P.G. Saffman, advisor by Donal A Gallagher( Book )

1 edition published in 1999 in English and held by 2 WorldCat member libraries worldwide

Randon advection of a passive scalar by James P Gleeson( Book )

1 edition published in 1999 in English and held by 2 WorldCat member libraries worldwide

Part I. Vortex dynamics in wake models. : Part II. Wave generation by David J Hill( Book )

1 edition published in 1998 in English and held by 2 WorldCat member libraries worldwide

Exact solutions for two-dimensional Stokes flow by Darren G Crowdy( Book )

1 edition published in 1998 in English and held by 2 WorldCat member libraries worldwide

A THEORY OF DISPERSION IN A POROUS MEDIUM by P. G Saffman( Book )

1 edition published in 1959 in English and held by 1 WorldCat member library worldwide

The thermal Rayleigh problem in perfect and ionized gases by Carlos Navarro-Cantero( Book )

1 edition published in 1967 in English and held by 1 WorldCat member library worldwide

The rotation of a gravitating sphere in a monatomic gas. The drag of a body moving transversely in a confined stratified fluid by Michael R Foster( Book )

1 edition published in 1969 in English and held by 1 WorldCat member library worldwide

The motion of a sphere in a cylinder filled with a viscous liquid and with a diameter slightly larger than the sphere diameter by Hermanus Snel( Book )

1 edition published in 1970 in English and held by 1 WorldCat member library worldwide

Dynamics of vorticity by P. G Saffman( )

1 edition published in 1981 in Undetermined and held by 1 WorldCat member library worldwide

Remarks are made about the status of research on the role of vorticity in fluid dynamics and some unsolved problems of current interest are described
Water Wave Instability Induced by a Drift Layer( Book )

1 edition published in 1989 in English and held by 1 WorldCat member library worldwide

A simple instability mechanism by which water waves can extract energy from a shear flow is isolated. A cubic equation is derived which provides the instability criteria and the growth rate. This mechanism is effective only if the surface drift velocity exceeds the minimum wave speed, which is approximately 23 cm/s in water, and only if the drift layer thickness exceeds a minimum value which is comparable with the unstable wavelength. In the situation of a sufficiently strong wind blowing over a flat calm, this mechanism is triggered early in the development stage, and appears to dominate the initial growth stages of centimeter waves. (JHD)
Application of the Wiener-Hermite Expansion to the Diffusion of a Passive Scalar in a Homogeneous Turbulent Flow by P. G Saffman( )

1 edition published in 1969 in Undetermined and held by 1 WorldCat member library worldwide

The stochastic expansion of Cameron, Martin, and Wiener is used for the velocity and concentration fields in a homogeneous turbulent flow convecting a passive scalar. The expansion is truncated and analytical solutions are obtained for the concentration field with the velocity distribution given and molecular diffusion neglected. For diffusion from a point source, the effective diffusivity is found in terms of Eulerian velocity correlations. For a statistically homogeneous scalar distribution, the spectrum function is determined in terms of the energy spectrum function. When the Prandtl number is large, the results obtained do not agree with the predictions of the universal equilibrium hypothesis
A model of vortex reconnection by P. G Saffman( )

1 edition published in 1990 in Undetermined and held by 1 WorldCat member library worldwide

A model is proposed to describe the breaking and rejoining of vortex lines which occurs when vortex filaments of equal and opposite strengths touch. It is based on the idea that viscosity cancels the vorticity where the filaments first touch. The weakening of the centrifugal force in the vortex core then leads to a local increase in the pressure which accelerates the fluid in the cores in the axial direction and convects the vorticity away from the initial contact and produces an apparent rejoining. Hyperbolic equations to describe the process are formulated and numerical solutions are obtained. Estimates of the timescales are made and compared with the experimental data of Schatzle (1987). Reasonable agreement is found
Viscous fingering in Hele-Shaw cells by P. G Saffman( )

1 edition published in 1986 in Undetermined and held by 1 WorldCat member library worldwide

The phenomenon of interfacial motion between two immiscible viscous fluids in the narrow gap between two parallel plates (Hele-Shaw cell) is considered. This flow is currently of interest because of its relation to pattern selection mechanisms and the formation of fractal, structures in a number of physical applications. Attention is concentrated on the fingers that result from the instability when a less-viscous fluid drives a more-viscous one. The status of the problem is reviewed and progress with the thirty-year-old problem of explaining the shape and stability of the fingers is described. The paradoxes and controversies are both mathematical and physical. Theoretical results on the structure and stability of steady shapes are presented for a particular formulation of the boundary conditions at the interface and compared with the experimental phenomenon. Alternative boundary conditions and future approaches are discussed
Effects of Long Waves on the Generation of Waves by Wind( Book )

2 editions published in 1997 in English and held by 1 WorldCat member library worldwide

The program objective was a quantitative understanding of the properties of the short wind generated waves relevant to the interpretation of remote sensing radar images of the ocean. To that effect, the work has focused on the interaction between long and short waves in the presence of water and wind shear
 
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Vortex dynamics
Alternative Names
Philip Saffman britischer angewandter Mathematiker

Philip Saffman British mathematician

Philip Saffman Brits wiskundige (1931-2008)

Philip Saffman matemático británico

Philip Saffman Matematico Inglese

Saffman, P. G.

Saffman, Philip G.

Saffman, Philip Geoffrey.

Sèffmèn. F. Dž.

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