Coronal waves: propagation in the multi-fluid description

2005 ◽  
Vol 364 (1839) ◽  
pp. 537-540 ◽  
Author(s):  
Redouane Mecheri ◽  
Eckart Marsch
Keyword(s):  
Wave Propagation ◽  
Plane Wave ◽  
Perturbation Analysis ◽  
Fluid Model ◽  
Wave Perturbation ◽  
Fourier Plane ◽  
Electron Inertia ◽  
Resonance Frequencies ◽  
Wave Effects ◽  
Waves Propagation

We study wave propagation in the low-β coronal plasma using a collisionless multi-fluid model. Neglecting the electron inertia, this model allows us to take into account ion-cyclotron wave effects that are absent in the magnetohydrodynamics model. To accomplish this, we perform a Fourier plane-wave perturbation analysis. Solving numerically the dispersion relations obtained from a two- and three-fluid model, dispersion curves for representative parameters of the solar corona are presented. The results reveal the presence of resonance frequencies that might play a role in coronal heating.

Helicon wave propagation: effect of electron inertia

1970 ◽  
Vol 4 (1) ◽  
pp. 43-50 ◽  
Author(s):  
B. Davies
Keyword(s):  
Wave Propagation ◽  
Dispersion Relation ◽  
Plane Wave ◽  
Propagation Effect ◽  
Electron Inertia ◽  
Cylindrical Plasma ◽  
Helicon Wave ◽  
Resistive Plasma ◽  
Helicon Waves

We investigate the dispersion relation for travelling helicon waves in a uniform non-resistive plasma. We show that the effect of electron inertia for a cylindrical plasma bounded by conducting walls is qualitatively different from the plane wave case, leading to significant differences in the dispersion relation at all frequencies in the range 0 < ω < Ωe.

Wave propagation in the presence of a spatially uniform external periodic magnetic field in two-temperature plasma

1982 ◽  
Vol 28 (1) ◽  
pp. 93-101
Author(s):  
Sanjay Kumar Ghosh
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
Fluid Model ◽  
Hydrodynamic Equations ◽  
Temperature Plasma ◽  
Uniform External Magnetic Field ◽  
Two Fluid Model ◽  
Excitation Conditions ◽  
Two Fluid ◽  
Two Temperature

Starting from the two-fluid model hydrodynamic equations, a dispersion relation is obtained for wave propagation through a two-temperature plasma perpendicular to the direction of the spatially uniform external magnetic field B0cosω0t and several excitation conditions are deduced.

scholarly journals Effects of Central Tube on Shape of Modal Duct of a Helicoid in a Simple Expansion Chamber

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Daniel Omondi Onyango ◽  
Robert Kinyua ◽  
Abel Nyakundi Mayaka
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Plane Wave ◽  
Acoustic Pressure ◽  
Three Dimensional ◽  
The Other ◽  
Expansion Chamber ◽  
Central Tube ◽  
Simple Expansion ◽  
Plane Wave Propagation

The shape of the modal duct of an acoustic wave propagating in a muffling system varies with the internal geometry. This shape can be either as a result of plane wave propagation or three-dimensional wave propagation. These shapes depict the distribution of acoustic pressure that may be used in the design or modification of mufflers to create resonance at cut-off frequencies and hence achieve noise attenuation or special effects on the output of the noise. This research compares the shapes of acoustic duct modes of two sets of four pitch configurations of a helicoid in a simple expansion chamber with and without a central tube. Models are generated using Autodesk Inventor modeling software and imported into ANSYS 18.2, where a fluid volume from the complex computer-aided-design (CAD) geometry is extracted for three-dimensional (3D) analysis. Mesh is generated to capture the details of the fluid cavity for frequency range between 0 and 2000Hz. After defining acoustic properties, acoustic boundary conditions and loads were defined at inlet and outlet ports before computation. Postprocessed acoustic results of the modal shapes and transmission loss (TL) characteristics of the two configurations were obtained and compared for geometries of the same helical pitch. It was established that whereas plane wave propagation in a simple expansion chamber (SEC) resulted in a clearly defined acoustic pressure pattern across the propagation path, the distribution in the configurations with and without the central tube depicted three-dimensional acoustic wave propagation characteristics, with patterns scattering or consolidating to regions of either very low or very high acoustic pressure differentials. A difference of about 80 decibels between the highest and lowest acoustic pressure levels was observed for the modal duct of the geometry with four turns and with a central tube. On the other hand, the shape of the TL curve shifts from a sinusoidal-shaped profile with well-defined peaks and valleys in definite multiples of π for the simple expansion chamber, while that of the other two configurations depended on the variation in wavelength that affects the location of occurrence of cut-on or cut-off frequency. The geometry with four turns and a central tube had a maximum value of TL of about 90 decibels at approximately 1900Hz.

Plane wave propagation in microstretch thermoelastic medium with microtemperatures

2014 ◽  
Vol 21 (16) ◽  
pp. 3403-3416
Author(s):  
Rajneesh Kumar ◽  
Mandeep Kaur ◽  
SC Rajvanshi
Keyword(s):  
Wave Propagation ◽  
Plane Wave ◽  
Thermoelastic Medium ◽  
Plane Wave Propagation
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