Topic
Thermal radiation
About: Thermal radiation is a research topic. Over the lifetime, 12290 publications have been published within this topic receiving 197186 citations. The topic is also known as: heat radiation.
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TL;DR: In this article, a generalization of the thermal discrete dipole approximation (TDDA) was proposed to describe the near-field radiative heat transfer between finite objects of arbitrary shape that exhibit magneto-optical (MO) activity.
Abstract: We present here a generalization of the thermal discrete dipole approximation (TDDA) that allows us to describe the near-field radiative heat transfer between finite objects of arbitrary shape that exhibit magneto-optical (MO) activity. We also extend the TDDA approach to describe the thermal emission of a finite object with and without MO activity. Our method is also valid for optically anisotropic materials described by an arbitrary permittivity tensor and we provide simple closed formulas for the basic thermal quantities that considerably simplify the implementation of the TDDA method. Moreover, we show that by employing our TDDA approach one can rigorously demonstrate Kirchhoff's radiation law relating the emissivity and absorptivity of an arbitrary MO object. Our work paves the way for the theoretical study of the active control of emission and radiative heat transfer between MO systems of arbitrary size and shape.
69 citations
Patent•
30 Sep 1994
TL;DR: In this article, a temperature-controlled laser sintering system includes a laser beam 12 which is focussed onto a Sintering bed 38 by a focussing mirror 26 and a set of scanning mirrors 32, 34.
Abstract: A temperature-controlled laser sintering system includes a laser beam 12 which is focussed onto a sintering bed 38 by a focussing mirror 26 and a set of scanning mirrors 32, 34. Thermal radiation 114 emitted from the sintering bed 38 are imaged to the scanning mirrors and to a dichroic beamsplitter 110 which reflects such radiation but passes the wavelength of the laser beam 12. The radiation 118 is focussed onto an optical detector 126 which provides a signal on a line 128 to a power control circuit 104. The power control circuit 104 controls a modulator 100 which modulates the power of the laser beam 112 so as to maintain the thermal radiation emission 114 (and thus the temperature at the sintering location) at a substantially constant level.
69 citations
TL;DR: In this article, the influence of radiation and temperature-dependent viscosity on the problem of unsteady MHD flow and heat transfer of an electrically conducting fluid past an infinite vertical porous plate taking into account the effect of viscous dissipation was investigated.
Abstract: This article investigates the influence of radiation and temperature-dependent viscosity on the problem of unsteady MHD flow and heat transfer of an electrically conducting fluid past an infinite vertical porous plate taking into account the effect of viscous dissipation. The governing equations are converted into a system of nonlinear ordinary differential equations via a local similarity parameter which is taken as a function of time. The resulting system of coupled nonlinear ordinary differential equations is solved numerically using the fourth order Runge-Kutta integration scheme with the shooting method. The numerical results for the velocity and the temperature are displayed graphically showing the effects of various parameters. The results show that increasing the Eckert number and decreasing the viscosity of air leads to a rise in the velocity, while increasing in the magnetic or the radiation parameters is associated with a decrease in the velocity. Also, an increase in the Eckert number leads to an increase in the temperature, whereas an increase in radiation parameter leads to a decrease in the temperature.
69 citations
TL;DR: In this article, the authors addressed flow in a non-Darcy porous medium flow is due to nonlinear stretching surface with variable thickness, which consists of salient features of nonlinear thermal radiation, viscous dissipation, Joule heating and homogeneous-heterogeneous reactions in whole analysis equal diffusions for reactants and autocatalyst are invoked.
69 citations
TL;DR: In this article, a fundamental theoretical study made to understand the interaction of surface radiation and natural convection in an air-filled cavity with a centrally placed thin heated plate was presented, which indicated a better homogenization of temperature field within the cavity by radiation.
69 citations