Simulations With Radiative3d A Software Tool For Radiative Transport In 3 D Earth Models

Author : William Godoy
Publisher :
ISBN 13 :
Total Pages : 171 pages
Book Rating : 4.:/5 (636 download)

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Download or read book NUMERICAL MODELING OF RADIATION HEAT TRANSFER IN ABSORBING, EMITTING AND SCATTERING MEDIA written by William Godoy and published by . This book was released on 2009 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this dissertation is the development of numerical models forsimulation of radiative heat transfer for a general 3D Cartesian, non-homogeneous, emitting, absorbing, scattering and non-gray media. The overall problem is dividedin three parts consisting of: i) the acceleration in the calculation of the non-grayradiative properties of the gas and droplets, ii) the solution of the radiative transferequation (RTE) and iii) the coupling of radiation effects with the gas phase and particlesfor time integration solution. For the first part of the study, Mie theory andthe HITEMP database are used to construct the exact radiative properties of theparticle-gas media on a line by line basis. A correlated-k method is devised to representthe gas (H2O and CO2) absorption coefficients in terms of frequency distribution for later coupling with the scattering from the particles (water droplets) on a narrowband basis.^A scaling procedure using the Sauter mean diameter is developed inorder to accelerate the calculation of the radiative properties of the particle distributionresulting in significant computational savings with little loss of accuracy. Next, a classical Discrete Ordinates Method (DOM-SN) with flux limiters or total variation diminishing (TVD) schemes for the angular and spatial discretization is formulated for the solution of the RTE in a 3D absorbing, emitting and scattering enclosure, being the final system of equations solved using a Newton-Krylov method. Inclusion of TVD schemes shows that convergence, accuracy and stability in the RTE solution are superior to classical step (upwind) or diamond (central) schemes. A first solutionfor the interaction of the radiative field with the participating media composed of atwo-phase particle-gas mixture is shown for the evaporation of water sprays due tothe absorption of radiative energy.^The study shows that the evolution of the diametersize distribution due to radiation effects can be modeled through its first twomoments and the introduction of a non-symmetric density function. Overall, results suggest that the proposed numerical approaches for each aspectof the complicated radiative transfer problem may lead to a potential practical solutionin real situations. Through these methods, radiation calculations are madefeasible since accuracy is balanced with the required computational times. The latterencourages the inclusion of radiation effects on practical engineering applicationssuch as, fluid mechanics, combustion processes, 3D atmospheres, among others. Thisinclusion may improve the understanding of the physics behind these applications, including radiation effects, allowing for further development of high fidelity modelingapproaches.