Acoustic Diffraction of a Plane Wave by Two Coplanar Parallel Perfectly Soft or Rigid Strips

1972 ◽  
Vol 50 (9) ◽  
pp. 928-939 ◽  
Author(s):  
D. L. Jain ◽  
R. P. Kanwal
Keyword(s):  
Magnetic Field ◽  
Cross Section ◽  
Normal Derivative ◽  
Field Amplitude ◽  
Far Field ◽  
Soft Or ◽  
Transmission Coefficients ◽  
Incident Plane ◽  
Acoustic Diffraction ◽  
Conducting Screen

The problem of diffraction of a normally incident plane acoustic wave by two parallel and coplanar infinite strips is considered. The assumed boundary conditions on the strips are the vanishing of either the total wave function or its normal derivative. Expressions are obtained for the first few terms of the series for the far-field amplitude and the scattering cross section when the wavelength is much larger than the distance between the outer edges of the strips. The corresponding results for two parallel and coplanar infinite slits in a soft or a rigid screen follow by applying Babinet's principle. This analysis also gives the transmission coefficients for the case of two infinite parallel slits in a thin conducting screen when the electric or magnetic field vectors of the incident plane monochromatic waves are polarized parallel to the edges of the slits.

Acoustic Diffraction by a Rigid Annular Spherical Cap

1972 ◽  
Vol 39 (1) ◽  
pp. 139-147 ◽  
Author(s):  
D. L. Jain ◽  
R. P. Kanwal
Keyword(s):  
Cross Section ◽  
Acoustic Waves ◽  
Circular Disk ◽  
Polar Axis ◽  
Field Amplitude ◽  
Far Field ◽  
Axially Symmetric ◽  
Spherical Cap ◽  
Time Harmonic ◽  
Acoustic Diffraction

The problem of the diffraction of time-harmonic axially symmetric acoustic waves by a perfectly rigid annular spherical cap is solved approximately by an integral equation technique. Formulas are derived for the far-field amplitude as well as the scattering cross section when the incident wave is a plane wave traveling along the polar axis. By taking appropriate limits, the solutions for the corresponding problems for an annular circular disk and a whole spherical cap are also presented.

The low frequency scalar diffraction by an elliptic disc

1967 ◽  
Vol 63 (4) ◽  
pp. 1273-1280 ◽  
Author(s):  
B. D. Sleeman
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Scattered Field ◽  
Low Frequency ◽  
Field Amplitude ◽  
Wave Number ◽  
Series Expansions ◽  
Far Field ◽  
Scalar Diffraction ◽  
Scattering Cross

SummaryThe problem of scalar Dirichlet diffraction of a plane wave by an elliptic disc is discussed. A scheme is given whereby the low frequency expansion of the scattered field may be readily obtained. Series expansions are obtained for the far-field amplitude up to and including the second order in the wave number. The first two terms of the scattering cross-section are also derived.

BACKSCATTERING FROM A CONDUCTING CYLINDER WITH A SURROUNDING SHELL

1960 ◽  
Vol 38 (12) ◽  
pp. 1665-1676 ◽  
Author(s):  
M. A. Plonus
Keyword(s):  
Cross Section ◽  
Propagation Constant ◽  
Scattering Cross Section ◽  
Graphical Form ◽  
Far Field ◽  
Scattering Cross ◽  
Conducting Cylinder ◽  
Incident Plane ◽  
Section Versus ◽  
Field Coefficient

Far-field backscattering from a perfectly conducting cylinder with a surrounding shell has been investigated. The spacing of the shell from the cylinder and thickness of the shell are arbitrary. The material in the shell is also arbitrary and is characterized by the propagation constant h. The incident plane wave is at right angles to the cylinder, and is either horizontally or perpendicularly polarized. When the shell is thin in units of wavelength a much simpler expression for the backscattered field coefficient is obtained. It was possible to express this coefficient in a form which resembles the coefficient from the conducting cylinder alone plus a perturbation term due to the shell. Another simplification resulted when the propagation constant h of the shell is much larger than the free-space propagation constant k.It was desirable to see what scattering properties a cylinder with a surrounding shell exhibits. The cylinder was chosen to be large with respect to wavelength and the shell spaced a resonant distance from the cylinder. The scattering cross section, for this particular combination of parameters was then given by a slowly converging series which proved too lengthy for hand-computation, and was then programmed for and computed by the IBM 704. The scattering cross section versus shell spacing is shown in graphical form.

The interaction of waves with a row of circular cylinders

1993 ◽  
Vol 251 ◽  
pp. 687-708 ◽  
Author(s):  
C. M. Linton ◽  
D. V. Evans
Keyword(s):  
Water Waves ◽  
Circular Cylinders ◽  
Far Field ◽  
Incident Plane Wave ◽  
Straightforward Manner ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Incident Plane ◽  
Multipole Expansions ◽  
Field Behaviour

The two-dimensional acoustics problem of the scattering of an obliquely incident plane wave by a row of equally-spaced circular cylinders is solved using multipole expansions. The method is superior to existing techniques available for this problem as it allows the far-field behaviour of the solution to be evaluated in a straightforward manner, and extensive results for the reflection and transmission coefficients are given. The problem described above has a direct analogue in the theory of water waves and this is also discussed.

scholarly journals Elusive Pure Anapole Excitation in Homogenous Spherical Nanoparticles with Radial Anisotropy

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Wei Liu ◽  
Bing Lei ◽  
Jianhua Shi ◽  
Haojun Hu ◽  
Andrey E. Miroshnichenko
Keyword(s):  
Cross Section ◽  
Plane Waves ◽  
Far Field ◽  
Spherical Nanoparticles ◽  
Magnetic Dipoles ◽  
Anisotropic Dielectric ◽  
Scattered Power ◽  
Incident Plane ◽  
Total Scattering Cross Section ◽  
Radial Anisotropy

For homogenous isotropic dielectric nanospheres with incident plane waves, Cartesian electric and toroidal dipoles can be tunned to cancel each other in terms of far-field scattering, leading to the effective anopole excitation. At the same time however, other multipoles such as magnetic dipoles with comparable scattered power are simultanesouly excited, mixing with the anopole and leading to a nonnegligible total scattering cross-section. Here, we show that, for homogenous dielectric nanospheres, radial anisotropy can be employed to significantly suppress the other multipole excitation, which at the same time does not compromise the property of complete scattering cancallation between Cartesian electric and toroidal dipoles. This enables an elusivepure anopoleexcitation within radially anisotropic dielectric nanospheres, which may shed new light on many scattering related fundamental researches and applications.

Flow Visualization by Means of Contactless Inductive Flow Tomography in the Presence of a Magnetic Brake

2015 ◽  
Vol 15 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Matthias Ratajczak ◽  
Thomas Wondrak ◽  
Klaus Timmel ◽  
Frank Stefani ◽  
Sven Eckert
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Flow Field ◽  
Continuous Casting ◽  
Flow Structure ◽  
Cross Section ◽  
Two Dimensional ◽  
Slab Casting ◽  
Two Dimensional Flow

AbstractIn continuous casting DC magnetic fields perpendicular to the wide faces of the mold are used to control the flow in the mold. Especially in this case, even a rough knowledge of the flow structure in the mold would be highly desirable. The contactless inductive flow tomography (CIFT) allows to reconstruct the dominating two-dimensional flow structure in a slab casting mold by applying one external magnetic field and by measuring the flow-induced magnetic fields outside the mold. For a physical model of a mold with a cross section of 140 mm×35 mm we present preliminary measurements of the flow field in the mold in the presence of a magnetic brake. In addition, we show first reconstructions of the flow field in a mold with the cross section of 400 mm×100 mm demonstrating the upward scalability of CIFT.

scholarly journals Magnetically induced termination of giant planet formation

2018 ◽  
Vol 619 ◽  
pp. A165 ◽  
Author(s):  
A. J. Cridland
Keyword(s):  
Magnetic Field ◽  
Cross Section ◽  
Planet Formation ◽  
Giant Planet ◽  
Effective Cross Section ◽  
Cold Start ◽  
Population Synthesis ◽  
Hot Start ◽  
Gas Accretion ◽  
Planetary Magnetic Field

Here a physical model for terminating giant planet formation is outlined and compared to other methods of late-stage giant planet formation. As has been pointed out before, gas accreting into a gap and onto the planet will encounter the planetary dynamo-generated magnetic field. The planetary magnetic field produces an effective cross section through which gas is accreted. Gas outside this cross section is recycled into the protoplanetary disk, hence only a fraction of mass that is accreted into the gap remains bound to the planet. This cross section inversely scales with the planetary mass, which naturally leads to stalled planetary growth late in the formation process. We show that this method naturally leads to Jupiter-mass planets and does not invoke any artificial truncation of gas accretion, as has been done in some previous population synthesis models. The mass accretion rate depends on the radius of the growing planet after the gap has opened, and we show that so-called hot-start planets tend to become more massive than cold-start planets. When this result is combined with population synthesis models, it might show observable signatures of cold-start versus hot-start planets in the exoplanet population.

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