editorial novel analytical and numerical methods in heat...

EditorialNovel Analytical and Numerical Methods in Heat TransferEnhancement and Thermal Management

Assunta Andreozzi,1 Guy Lauriat,2 Qiuwang Wang,3 Sotirios Karellas,4 and Yogesh Jaluria5

1Dipartimento di Ingegneria Industriale, Universita degli Studi di Napoli Federico II, 80125 Napoli, Italy2Laboratoire de Modelisation et Simulation Multi Echelle, Equipe Transferts de Chaleur et de Matiere, Universite PARIS-EST,77454 Marne-la-Vallee Cedex 2, France3School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China4Laboratory of Steam Boilers andThermal Plants, School of Mechanical Engineering, National Technical University of Athens,Zografou, 15780 Athens, Greece5Mechanical and Aerospace Engineering Department, Rutgers, the State University of New Jersey, Piscataway, NJ 08854-8058, USA

Correspondence should be addressed to Assunta Andreozzi; [email protected]

Received 5 November 2015; Accepted 5 November 2015

Copyright © 2016 Assunta Andreozzi et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

Heat transfer enhancement (HTE) and thermal management(THEMA) are very attractive issues in the research andindustry fields. They play an important role in improvingenergy efficiency and developing high performance thermalsystems. HTE and THEMA techniques are powerful toolsto increase and improve heat transfer rate and thermalperformance as well as to reduce the size of heat transfersystems in installation and operational costs.

The basic purpose of this special issue is to collect originalresearch articles on the most recent analytical and numericalmodels applied in this field, with the purpose of providingguidelines for future research direction.

This special issue showed novel and interesting analyticaland numerical procedures applied in heat transfer enhance-ment and thermal management.

The topics of the accepted papers cover a wide area ofthe heat transfer field, from the transient heat transfer to theheat transfer in porous media and to the system design andoptimization in forced convection.

A brief overview of each manuscript selected for thisspecial issue is presented in the following, in alphabeticalorder of the first author.

C. Devaraj et al. investigate numerically natural convec-tion heat transfer in a two-dimensional square enclosure atvarious angles of inclination using a finite volume based

computational procedure.Theheat transfer is from a constanttemperature heat source of finite length centered at one ofthe walls to the cold wall on the opposite side while theremaining walls are insulated. The authors analyze the effectof area ratio of the heat source, Rayleigh number, and angleof inclination of the enclosure on the flow field and theheat transfer characteristics. Moreover the paper shows anexhaustive verification and validation section and gives heattransfer correlation equations for each angle of inclination ofenclosure investigated which are in good agreement with thenumerical results.

I. Simoes et al. present, in their paper, a set of fullyanalytical solutions, together with explicit expressions, in thetime and frequency domain for the heat conduction responseof homogeneous unbounded and of bounded rectangularspaces (three-, two-, and one-dimensional spaces) subjectedto point, line, and plane heat diffusion sources. The authorspay particular attention to the case of spatially sinusoidal,harmonic line sources. This last solution, referred to in theliterature as the 2.5D problem. Proposed Green’s functionsare combined using an image source technique to modela half space, a corner, a layer system, a laterally confinedlayer system, a solid rectangular column, a solid rectangularcolumn with an end cross section, and a 3D parallelepipedinclusion. This is the first such derivation that is expected

Hindawi Publishing CorporationJournal of Applied MathematicsVolume 2016, Article ID 8450794, 2 pageshttp://dx.doi.org/10.1155/2016/8450794

2 Journal of Applied Mathematics

to be efficient for formulating 3D thermodynamics problemsusing boundary elements and integral transforms. The solu-tions are validated by comparing computed results with thoseobtained directly in the time domain.

T.-W. Tu and S.-Y. Lee develop for the first time ananalytical solution for the heat transfer in hollow cylin-ders with time-dependent boundary condition and time-dependent heat transfer coefficient at different surfaces. Themethodology employed by the authors is an extension ofthe shifting function method and permits transforming thesystem into a partial differential equation with homogenousboundary conditions. The transformed system is thus solvedby series expansion theorem. Limiting cases of the solutionare studied and numerical results are compared with thosein the literature. The authors investigate the influence ofphysical parameters on the temperature distribution of ahollow cylinder along the radial direction, too.

X. Zhang and R. Li present two papers. In the first onethey investigate the cooling and radiation of a vectoringnozzle and compute the gas spectral characteristic in infraredband, adopting a narrow band model. The radiative heattransfer between the hot gas and the wall is consideredwith an enclosure model whereas the calculation of filmcooling is performed through a cooling effectivenessmethod.A coupled heat balance equation of heat flux and walltemperature is established on the multilayer structure of thenozzle, including the wall, heat shield, and outer shield, anda Newton-Raphson scheme is taken for solution. The resultsverification is carried out by means of the investigation oftemperature on the expansion part of an experimental nozzlein NASA TN D-1988. The authors also investigate anothervectoring nozzle with a multirow of film cooling.

The same authors investigate the similarity of plumeradiation between reduced scaling solid rocket models andfull scale ones in ground. In the second paper the authorscompute flow and radiation of plume from solid rockets withscaling ratio from 0.1 to 1, using CFD code. The radiativetransfer equation is solved by the finite volumemethod in theinfrared band 2∼6𝜇m. The spectral characteristics of plumegases have been calculated with the weighted-sum-of-gray-gas (WSGG) model, and those of the Al

2O3particles have

been solved by the Mie scattering model. The research showsa good similarity between spectral variations of plumes fromdifferent scaling solid rockets.

Acknowledgments

The Guest Editors would like to thank all authors for theircontributions to this special issue and the many externalreviewers for their excellent work.

Assunta AndreozziGuy Lauriat

Qiuwang WangSotirios KarellasYogesh Jaluria

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