Effective-medium theory for multilayer metamaterials: Role of near-field corrections

2020 ◽  
Vol 102 (17) ◽  
Author(s):  
Tong Liu ◽  
Shaojie Ma ◽  
Bowen Yang ◽  
Shiyi Xiao ◽  
Lei Zhou
Keyword(s):  
Effective Medium Theory ◽  
Near Field ◽  
Effective Medium ◽  
Medium Theory

Application Conditions of Effective Medium Theory in Near-Field Radiative Heat Transfer Between Multilayered Metamaterials

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
X. L. Liu ◽  
T. J. Bright ◽  
Z. M. Zhang
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Effective Medium Theory ◽  
Near Field ◽  
Effective Medium ◽  
Medium Theory ◽  
Metal Metal ◽  
Doped Silicon ◽  
Silicon And Germanium

This work addresses the validity of the local effective medium theory (EMT) in predicting the near-field radiative heat transfer between multilayered metamaterials, separated by a vacuum gap. Doped silicon and germanium are used to form the metallodielectric superlattice. Different configurations are considered by setting the layers adjacent to the vacuum spacer as metal–metal (MM), metal–dielectric (MD), or dielectric–dielectric (DD) (where M refers to metallic doped silicon and D refers to dielectric germanium). The calculation is based on fluctuational electrodynamics using the Green's function formulation. The cutoff wave vectors for surface plasmon polaritons (SPPs) and hyperbolic modes are evaluated. Combining the Bloch theory with the cutoff wave vector, the application condition of EMT in predicting near-field radiative heat transfer is presented quantitatively and is verified by exact calculations based on the multilayer formulation.

scholarly journals Porous and cracked rocks elasticity: Macroscopic poroelasticity and effective media theory

2021 ◽  
pp. 108128652110220
Author(s):  
Jérôme Fortin ◽  
Yves Guéguen
Keyword(s):  
Effective Medium Theory ◽  
Effective Medium ◽  
Microstructural Characteristics ◽  
Medium Theory ◽  
Effective Medium Model ◽  
Effective Media ◽  
Effective Media Theory ◽  
Fluid Properties ◽  
Grain Properties

Macroscopic poroelasticity and effective medium theory are two independent approaches which can be used to analyze the role of pores, cracks, and fluid on elastic properties. Macroscopic poroelasticity belongs to the macroscopic framework of thermodynamics whereas effective medium theory expresses the medium properties in terms of microstructural characteristics (pore and crack shape, etc.) and component properties (fluid properties, solid grain properties, etc.). In this paper, we review the fundamental assumptions and results of both approaches, and show that they are complementary but do not apply over the same range of conditions. A compilation of data is reported, in various dry and saturated rocks, to show the validity of the Gassmann equation and the dispersion between unrelaxed modulus –where effective medium model applies- and relaxed modulus –where poroelasticity applies.

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