Classical Electrodynamics and Acoustics: Sound Radiation by Moving Multipoles

1997 ◽  
Vol 119 (2) ◽  
pp. 271-282 ◽  
Author(s):  
G. C. Gaunaurd ◽  
T. J. Eisler
Keyword(s):  
Dirac Equation ◽  
Free Field ◽  
Sound Radiation ◽  
Equation Of Motion ◽  
Rotating Machinery ◽  
Classical Electrodynamics ◽  
Radiation Patterns ◽  
Frequency Distributions ◽  
Acoustic Sources ◽  
Power Radiation

In classical electrodynamics (CED) P. Dirac used the average of retarded and advanced fields to represent the bound field and their difference to represent the free field in his derivation of the (Lorentz-Dirac) equation of motion for an electron. The latter skew-symmetric combination filtered out the radiation part of the field. It can also be used to derive many properties of the power radiated by acoustic sources, such as angular and frequency distributions. As in CED there is radiation due to source acceleration and radiation patterns exhibit the “headlight effect.” Power radiation patterns are obtained by this approach for point multipoles undergoing various motions. Applications to sound radiation problems from rotating machinery are shown. Numerous computed plots illustrate all cases.

A Problem Connected with the Schott Term in Classical Electrodynamics

1976 ◽  
Vol 31 (12) ◽  
pp. 1500-1506
Author(s):  
M. Sorg
Keyword(s):  
Dirac Equation ◽  
Equation Of Motion ◽  
Classical Electrodynamics ◽  
Lorentz Model

Abstract It is shown that the well-known "4/3-problem" of the old Abraham-Lorentz model for the extended electron is still present in Rohrlich's redefinition of the electromagnetic four-momentum, if the latter is applied to an accelerated electron. The notorious factor 4/3 emerges now in connection with the Schott term. Since this term is an indispensable constituent of the Lorentz-Dirac equation of motion for the radiating electron, this equation appears to be not completely reliable.

Classical Electrodynamics and Acoustics, Part 2: Sound Radiation by Moving Quadrupoles

1999 ◽  
Vol 121 (1) ◽  
pp. 126-130 ◽  
Author(s):  
G. C. Gaunaurd ◽  
T. J. Eisler
Keyword(s):  
Sound Radiation ◽  
Classical Electrodynamics ◽  
Radiation Patterns

Our earlier work in Part 1 of this paper [1] is here extended to quadrupole distributions and point quadrupoles (i.e., stresses) in arbitrary motion. Radiation patterns are obtained and displayed in many relevant cases.

Classical, Covariant Finite-size Model of the Radiating Electron

1974 ◽  
Vol 29 (11) ◽  
pp. 1671-1684 ◽  
Author(s):  
M. Sorg
Keyword(s):  
Dirac Equation ◽  
Finite Size ◽  
Finite Extension ◽  
Equation Of Motion ◽  
Mass Renormalization ◽  
Classical Electron ◽  
Size Model

The finite extension of the classical electron is defined in a new, covariant manner. This new definition enables one to calculate exactly the bound and emitted four-momentum and to find an equation of motion different from the Lorentz-Dirac equation and from other equations proposed in the literature. Neither mass renormalization nor use of advanced quantities nor asymptotic conditions are necessary. Runaway solutions and pre-acceleration do not occur in the framework of the model presented here.

Free-field sound radiation measurement with multiple synchronous cameras

Measurement ◽  
2021 ◽  
pp. 110605
Author(s):  
Paolo Gardonio ◽  
Roberto Rinaldo ◽  
Loris Dal Bo ◽  
Roberto Del Sal ◽  
Emanuele Turco ◽  
...  
Keyword(s):  
Free Field ◽  
Sound Radiation ◽  
Radiation Measurement ◽  
Field Sound

Classical electrodynamics: the equation of motion

1974 ◽  
Vol 76 (1) ◽  
pp. 359-367 ◽  
Author(s):  
P. A. Hogan
Keyword(s):  
Electromagnetic Field ◽  
Charged Particle ◽  
Scalar Field ◽  
World Line ◽  
External Electromagnetic Field ◽  
Equation Of Motion ◽  
The Self ◽  
Classical Electrodynamics ◽  
Field Equations ◽  
The World

In this paper we derive the Lorentz-Dirac equation of motion for a charged particle moving in an external electromagnetic field. We use Maxwell's electromagnetic field equations together with the assumptions (1) that all fields are retarded and (2) that the 4-force acting on the charged particle is a Lorentz 4-force. To define the self-field on the world-line of the charge we utilize a contour integral representation for the field due to A. W. Conway. This by-passes the need to define an ‘average field’. In an appendix the case of a scalar field is briefly discussed.

Sound radiation from a centrifugal blower in a free field.

1996 ◽  
Vol 99 (4) ◽  
pp. 2509-2529
Author(s):  
Shigong Su ◽  
Sean F. Wu ◽  
Morris Y. Hsi
Keyword(s):  
Free Field ◽  
Sound Radiation ◽  
Centrifugal Blower

Causality Violation and Non-local Generalization of the Lorentz-Dirac Equation

1977 ◽  
Vol 32 (3-4) ◽  
pp. 319-326
Author(s):  
P. Alber ◽  
W. Heudorfer ◽  
M. Sorg
Keyword(s):  
Dirac Equation ◽  
Equation Of Motion ◽  
Local Theory ◽  
Constant Force ◽  
Dirac Theory ◽  
Local Equation ◽  
Causality Violation ◽  
Finite Duration ◽  
Non Local

AbstractIt is demonstrated by a concrete example (constant force of finite duration) that the recently proposed, non-local equation of motion for the radiating electron does exhibit the effect of causality violation. This phenomenon, which occurs in the non-local theory in form of self-oscillations, is however less severe than in the Lorentz-Dirac theory, if only physically reasonable forces are admitted.

scholarly journals THE SELF-FORCE OF A CHARGED PARTICLE IN CLASSICAL ELECTRODYNAMICS WITH A CUTOFF

1999 ◽  
Vol 13 (03) ◽  
pp. 315-324 ◽  
Author(s):  
J. FRENKEL ◽  
R. B. SANTOS
Keyword(s):  
Charged Particle ◽  
Special Relativity ◽  
Point Charge ◽  
Equation Of Motion ◽  
The Self ◽  
Classical Electrodynamics ◽  
Exact Equation ◽  
Electromagnetic Mass ◽  
Self Force

We discuss, in the context of classical electrodynamics with a Lorentz invariant cutoff at short distances, the self-force acting on a point charged particle. It follows that the electromagnetic mass of the point charge occurs in the equation of motion in a form consistent with special relativity. We find that the exact equation of motion does not exhibit runaway solutions or non-causal behavior, when the cutoff is larger than half of the classical radius of the electron.

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