scholarly journals Radiative Transfer and Generalized Wind

Entropy ◽  
2020 ◽  
Vol 22 (10) ◽  
pp. 1153 ◽  
Author(s):  
Christopher Essex ◽  
Indrani Das
Keyword(s):  
Radiative Transfer ◽  
Entropy Production ◽  
Velocity Fields ◽  
Radiative Energy ◽  
Classical Notion

Dissimilar flows can be compared by exploiting the fact that all flux densities divided by their conjugate volume densities form velocity fields, which have been described as generalized winds. These winds are an extension of the classical notion of wind in fluids which puts these distinct processes on a common footing, leading to thermodynamical implications. This paper extends this notion from fluids to radiative transfer in the context of a classical two-stream atmosphere, leading to such velocities for radiative energy and entropy. These are shown in this paper to exhibit properties for radiation previously only thought of in terms of fluids, such as the matching of velocity fields where entropy production stops.

scholarly journals Relationship between Envelope Structure and Energy Source of Non-Thermal Motions

1980 ◽  
Vol 51 ◽  
pp. 292-292
Author(s):  
Hiroyasu Ando
Keyword(s):  
Mechanical Energy ◽  
Heat Engine ◽  
Velocity Fields ◽  
Radiative Energy ◽  
Ionization Zone ◽  
Structure Dependence ◽  
Surface Activities ◽  
Outer Atmosphere ◽  
Solar Type ◽  
Clear Relation

AbstractThe ionization zone in the envelope of the late type stars is reasonably considered as a heat engine to transform some of the radiative energy into mechanical energy. This idea is suggestive for explaining Linsky and Haisch’s (1979) observation, which shows the sharp division into solar-type and non-solar type stars in the outer atmosphere. Also non-thermal velocity fields in “microturbulence” and in Wilson-Bappu effect are proposed to be formed essentially from this engine. Therefore, their envelope structure dependence observationally obtained is possibly explained by the envelope parameters (g, Te) dependence of the generated mechanical energy flux in this layer. If “microturbulence” is not contaminated by the other surface activities, it is expected to show a clear relation with envelope parameters (g, Te) similar to Wilson-Bappu effect.

scholarly journals Comoving-frame radiative transfer in arbitrary velocity fields

2009 ◽  
Vol 501 (2) ◽  
pp. 813-820 ◽  
Author(s):  
S. Knop ◽  
P. H. Hauschildt ◽  
E. Baron
Keyword(s):  
Radiative Transfer ◽  
Velocity Fields ◽  
Arbitrary Velocity

scholarly journals Radiative transfer modeling of the Hanle effect in convective atmospheres

2006 ◽  
Vol 2 (S239) ◽  
pp. 44-51
Author(s):  
Javier Trujillo Bueno
Keyword(s):  
Radiative Transfer ◽  
Magnetic Flux ◽  
Magnetic Energy ◽  
Radiative Energy ◽  
Energy Losses ◽  
Solar Photosphere ◽  
Hanle Effect ◽  
Molecular Lines ◽  
Outer Atmosphere ◽  
Radiative Transfer Modeling

AbstractThis paper summarizes the results of a recent investigation on the Hanle effect in atomic and molecular lines, which indicates that there is a vast amount of “hidden” magnetic energy and (unsigned) magnetic flux in the internetwork regions of the quiet solar photosphere. This hidden magnetic energy, localized in the (intergranular) downflowing plasma of the solar photosphere, is carried mainly by tangled fields at sub-resolution scales with strengths between the equipartition field values and ∼1 kG, and is more than sufficient to compensate the radiative energy losses of the solar outer atmosphere.

Investigation of Radiative Transfer in Nongray Gases Using a Narrow Band Model and Monte Carlo Simulation

1994 ◽  
Vol 116 (1) ◽  
pp. 160-166 ◽  
Author(s):  
J. Liu ◽  
S. N. Tiwari
Keyword(s):  
Monte Carlo ◽  
Radiative Transfer ◽  
Narrow Band ◽  
Heat Fluxes ◽  
Radiative Energy ◽  
Band Model ◽  
Spectral Correlation ◽  
The Monte Carlo Method ◽  
Finite Volume Element ◽  
Narrow Band Model

The Monte Carlo method (MCM) is applied to analyze radiative heat transfer in nongray gases. The nongray model employed is based on the statistical narrow band model with an exponential-tailed inverse intensity distribution. The amount and transfer of the emitted radiative energy in a finite volume element within a medium are considered in an exact manner. The spectral correlation between transmittances of two different segments of the same path in a medium makes the statistical relationship different from the conventional relationship that only provides the noncorrelated results for nongray analysis. Two features of the MCM that are different from other nongray numerical methods are discussed. The simplicity of the MCM is demonstrated by considering the case of radiative transfer between two reflecting walls. The results for the radiative dissipation distributions and the net radiative wall heat fluxes are obtained for uniform, parabolic, and boundary layer type temperature profiles, as well as for a parabolic concentration profile. They are compared with available results of other methods. Good agreements are found for all the cases considered.

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