A half space moment approximation to the radiative heat transfer equations

2003 ◽  
Vol 83 (12) ◽  
pp. 853-858 ◽  
Author(s):  
B. Dubroca ◽  
M. Frank ◽  
A. Klar ◽  
G. Thömmes
Keyword(s):  
Heat Transfer ◽  
Half Space ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Moment Approximation ◽  
Transfer Equations

NUMERICAL PASSAGE FROM RADIATIVE HEAT TRANSFER TO NONLINEAR DIFFUSION MODELS

2001 ◽  
Vol 11 (05) ◽  
pp. 749-767 ◽  
Author(s):  
A. KLAR ◽  
C. SCHMEISER
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Nonlinear Diffusion ◽  
Radiative Heat ◽  
Mean Free Path ◽  
Rigorous Results ◽  
Asymptotic Preserving ◽  
Milne Problem ◽  
Transfer Equations ◽  
Radiative Transfer Equations

Radiative heat transfer equations including heat conduction are considered in the small mean free path limit. Rigorous results on the asymptotic procedure leading to the equilibrium diffusion equation for the temperature are given. Moreover, the nonlinear Milne problem describing the boundary layer is investigated and an existence result is proven. An asymptotic preserving scheme for the radiative transfer equations with the diffusion scaling is developed. The scheme is based on the asymptotic analysis. It works uniformly for all ranges of mean free paths. Numerical results for different physical situations are presented.

A HIERARCHY OF APPROXIMATIONS TO THE RADIATIVE HEAT TRANSFER EQUATIONS: MODELLING, ANALYSIS AND SIMULATION

2005 ◽  
Vol 15 (04) ◽  
pp. 643-665 ◽  
Author(s):  
MATTHIAS SCHÄFER ◽  
MARTIN FRANK ◽  
RENÉ PINNAU
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Numerical Results ◽  
Well Posedness ◽  
Direct Solution ◽  
Modelling Analysis ◽  
Transfer Equations ◽  
Moment Models

We thoroughly investigate a hierarchy of approximations to the radiative heat transfer equations which is intermediate between moment models and the direct solution. We discuss the modelling of this hierarchy, prove well-posedness and physically expected bounds, and show numerical results validating our approach.

Using Infrared Thermography for Detecting Defects on Surfaces With Low and Variable Emissivity

2009 ◽  
Author(s):  
Christopher Dalton ◽  
Brandon Olson ◽  
Feng C. Lai
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Performance Enhancement ◽  
System Development ◽  
Computer Software ◽  
Infrared Scanning ◽  
Transfer Equations ◽  
Infrared Cameras ◽  
High Emissivity

Currently infrared scanning technology has been successfully applied for the detection of a wide variety of defects in many applications provided that the surfaces have a high emissivity that doesn’t reflect radiation from outside sources. However, surfaces with low and variable emissivity present a challenge for the application of this technology because infrared cameras and sensors cannot differentiate between the emitted radiation from the surface of interest and those reflected from outside sources. The system presented is an attempt to reduce and/or remove the effects of reflected radiation to increase the system’s applicability beyond the limit of high emissivity surfaces. Physical hardware and computer software are used in concert with radiative heat transfer equations to first determine the emissivity of each point on the surface, then use that information obtained to accurately depict the surface temperature. While this newest iteration of the system development has addressed many important issues regarding accuracy, efficiency as well as performance enhancement in the removal of the artifacts of reflected radiation, the technique still has difficulties to be applied to most surfaces with variable emissivity.

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