An investigation of surface shape effects on near-field radiative transfer

Radiative transfer;Electromagnetism;Near-field transfer

Prussing, Keith F. ; Cathcart, J. M. Physics Zangwill, Andrew Kennedy, Brian Zhang, Zhuomin Otte, A. N. ; Cathcart, J. M.

University:Georgia Institute of Technology

Department:Physics

关键词: Radiative transfer;    Electromagnetism;    Near-field transfer;   

Others  :  https://smartech.gatech.edu/bitstream/1853/54321/1/PRUSSING-DISSERTATION-2015.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

It has been shown that the energy exchange between two objects can begreatly enhanced when the separation between the objects is on the orderof the wavelength of thermal emission.The earliest theoretical andcomputational work focused on simple planar and spherical geometries, orthey resorted to approximations that separated the object to outside ofthe thermalwavelength \(\lambda_T = hc/(k_BT)\).Since those originalworks, the study of near-field energy exchange has expanded to objectshapes that can be described by a separable coordinate system using aspectral expansion of the dyadic Green function of the system.Theboundary element method has also been used to study arbitrary shapes inthermal equilibrium.Application of these new expansion methods togeneral shapes out of thermal equilibrium will facilitate in theoptimization of nanoscale structures.A three step process is used to investigate the effects of object shapeon the total and directionality of theenergy exchange between objects.First, a general expression for the energy flux between the objects willbe formulated.Second, a computational method to evaluate theexpression will be implemented.Finally, the effects of varying thesurface geometry will be explored.The computational results demonstrate that the total energy exchangebetween two bodies is influenced by the surface shape of the objectseven when the surface areas are held constant.While the primaryincrease over the classical blackbody energy exchange \(\sigma T^4 A\)is primarily governed by separation of the surfaces, we show that theview factors from classical far-field radiative transfer can be used topredict the change in the total energy exchange from a referenceconfiguration at the same separation when the surface area of the twoobjects is comparable.Additionally, we demonstrate that the spatialdistribution of the energy exchange can be localized into small spatialregion with a peak value increased over \SI{30}{\percent} by using twoobjects with dramatically different projected areas.