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Integration of an absorption coefficient over a path from s 1 and s 2 affords the optical thickness (τ) of that path, a dimensionless quantity that is used in some variants of the Schwarzschild equation. When emission is ignored, the incoming radiation is reduced by a factor for 1/e when transmitted over a path with an optical thickness of 1.
In mathematics and physics, the heat equation is a parabolic partial differential equation. The theory of the heat equation was first developed by Joseph Fourier in 1822 for the purpose of modeling how a quantity such as heat diffuses through a given region. Since then, the heat equation and its variants have been found to be fundamental in ...
m −1: Spectral radiant flux absorbed and scattered by a volume per unit length, divided by that received by that volume. Directional attenuation coefficient: μ Ω: m −1: Radiance absorbed and scattered by a volume per unit length, divided by that received by that volume. Spectral directional attenuation coefficient: μ Ω,ν μ Ω,λ: m −1
The propagation of radiation through a medium is affected by absorption, emission, and scattering processes. The equation of radiative transfer describes these interactions mathematically. Equations of radiative transfer have application in a wide variety of subjects including optics, astrophysics, atmospheric science, and remote sensing.
Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes.
Calculation of radiative heat transfer between groups of objects, including a 'cavity' or 'surroundings' requires solution of a set of simultaneous equations using the radiosity method. In these calculations, the geometrical configuration of the problem is distilled to a set of numbers called view factors , which give the proportion of ...
Heat is the flow of thermal energy driven by thermal non-equilibrium, so the term 'heat flow' is a redundancy (i.e. a pleonasm). Heat must not be confused with stored thermal energy, and moving a hot object from one place to another must not be called heat transfer. However, it is common to say ‘heat flow’ to mean ‘heat content’. [1]
Most writers use it as a synonym for heat capacity, the ability of a body to store thermal energy. It is typically referred to by the symbol C th, and its SI unit is J/K or J/°C (which are equivalent). However: Christoph Reinhart at MIT describes thermal mass as its volume times its volumetric heat capacity. [1]