DOCSLIB.ORG

Acoustic Velocity and Attenuation in Magnetorhelogical Fluids Based on an Effective Density Fluid Model

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Acoustic Velocity and Attenuation in Magnetorhelogical Fluids Based on an Effective Density Fluid Model MATEC Web of Conferences 45, 001 01 (2016) DOI: 10.1051/matecconf/201645001 01 C Owned by the authors, published by EDP Sciences, 2016 Acoustic Velocity and Attenuation in Magnetorhelogical fluids based on an effective density fluid model Min Shen1,2 , Qibai Huang 1 1 Huazhong University of Science and Technology in Wuhan,China 2 Wuhan Textile University in Wuhan,China Abstract. Magnetrohelogical fluids (MRFs) represent a class of smart materials whose rheological properties change in response to the magnetic field, which resulting in the drastic change of the acoustic impedance. This paper presents an acoustic propagation model that approximates a fluid-saturated porous medium as a fluid with a bulk modulus and effective density (EDFM) to study the acoustic propagation in the MRF materials under magnetic field. The effective density fluid model derived from the Biot’s theory. Some minor changes to the theory had to be applied, modeling both fluid-like and solid-like state of the MRF material. The attenuation and velocity variation of the MRF are numerical calculated. The calculated results show that for the MRF material the attenuation and velocity predicted with this effective density fluid model are close agreement with the previous predictions by Biot’s theory. We demonstrate that for the MRF material acoustic prediction the effective density fluid model is an accurate alternative to full Biot’s theory and is much simpler to implement. 1 Introduction Magnetorheological fluids (MRFs) are materials whose properties change when an external electro-magnetic field is applied. They are considered as “smart materials” because their physical characteristics can be adapted to different conditions. Hence, MRFs material can be used (a)No magnetic field in design of active sound barriers to control noise transmission loss and for modification of noise absorption characteristics of sound absorbing materials [1]. The MRFs consist of micron size magnetically permeable particles suspended in a carrying liquid such (b) Applied Magnetic field H as the mineral or silicon oil. From the point of view of the inner structure, the particles are scattered randomly in the Figure.1 The MR effect:(a) the particles in the absence of liquid carrier in the absence of magnetic fields shown in magnetic fields;(b) particles magnetized and form columns Figure.1(a). When a magnetic field is applied to the fluid, when applied field; the particles magnetized and chain-like structures that align in the direction of the applied field as depicted in Since the discovery of the magnetorheology, only a Figure.1(b). In the presence of shear strain, the particles few works have been published in acoustic properties of aligned as columnar microstructure, in turn dramatically the MRF. Malinovsky et al.[2-3] designed actively change its acoustic impedance control magnetic field. electro-magnetically controlled acoustic metamaterial. However, if the magnetic field is removed, the They construct negative mass employs mass-spring suspension turns to a Newtonian fluid and the transition oscillator build into another mass. A lattice of such between these two phases is highly reversible, which “mass-in-mass” elements could be highly attenuated for provides a unique feature of electric- or magnetic-field acoustic/vibration waves. An one dimensional chain controllability of acoustic impedance of MRF. This model discussed based on discrete elements with feature has inspired the design of new active sound effective mass density and elastic modulus. In their study, barriers to control noise transmission loss or as acoustic the theoretical model of acoustic wave propagation in metamaterials with negative effective dynamic bulk [ MRF is based on one dimensional wave equation in the modulus 2-3]. elastic medium. This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits distribution, and reproduction in any medium, provided the original work is properly cited. Article available at http://www.matec-conferences.org or http://dx.doi.org/10.1051/matecconf/20164501001 MATEC Web of Conferences Howarth et al[4] conducted a series of acoustic where is the toal mass density , f is the pore fluid experiments at the National High Magnetic Field Laboratory in Tallahassee, Florida. The acoustic sound mass density and s is the particle mass density. speed of MR fluids was measured as functions of applied The material coefficients are magnetic field strength, normal and orthogonal field HKKDKK 2 (6) orientations, and acoustic frequency. Their presentation [(rb ) / ( b )] b (4 / 3) discussed measurement methodology and preliminary C( KKKDKrbr ) /( b )ˈ (7) results about the MRF material. 2 In previous work, Shen and Huang [5] present the M/() KDKrbˈ (8) acoustic model of MRF materials based on the Biot-Stoll DK KK model[6-8]. The Biot’s model is an useful extension of rrr[1 ( / 1)] (9) the equivalent fluids description, which takes into We note that K is the bulk modulus of individual account the stiffness of the frame and demonstrates that r two compressional waves and one shear wave can particles and K f is th bulk moulus of the base fluid.The propagate in porous materials. For the case where a F strong coupling exists between the fluid and the frame, parameter representsthe deviation from Poiseuille flow the two compressional wave exhibit very different as frequency increases. Biot derived an expression for properties, and are identified as the slow wave and the F that in the present notation is fast wave. The Biot-Stoll model is a comprehensive T()/4 F() (10) model. It is necessary to derive an approximate equation 12 iT ()/ for simplify practical application acoustic wave propagation in MRF suspensions. with This paper presents an effective density fluid model ()() iJ i that studies the acoustic propagation in the MRF material T( ) 1 (11) Ji under magnetic field to simple the Biot’s model. The 0 () effective density fluid model (EDFM) approximates a where J and J are cylindrical Bessel functions and fluid-saturated porous medium as a fluid with a bulk 1 0 modulus and effective density derived from Biot’s theory. f a (12) 2 Acoustic Model The parameter a is the pore size parameter. Johnson et al[9]. Examined the problem of a pressure gradient 2.1 The Biot’s model applied across a porous sample and found that for a porous media consisting of nonintersecting canted tubes the When an acousitc wave propagates in a porous, elastic,solid relationship for a medium saturated by a visous fluid. The Biot’s model considers that two compressionl waves and one shear wave 8 a (13) can propagate in a porous medium simultaneously[6-8]. Let u is displacement of the frame, U is displacement of the pore fluid relative to the frame. Using Eqs.(3) and (3),a fourth-order polynomial for the complex wave number k can be found. The soltion gives u .ss . (1) two different wave numbers corresponding to the Biot fast ()uU ..ff and slow waves. Both these waves show significant (2) dispersion. where is the porosity. Biot’s equations for the scalar potensials are then given as (using a plane wave solution 2.2 The effetive density fluid model exp[ikx ( . t )]) 22 2 2 Taking the Kb ==0 limit of Biot theory is () kHsf kC () s f (3) motivated by the fact that for magnetroheological fluids the frame and shear moduli are much lower than the other kC22 kM 2 2 ()sf () fsff / moduli[10-12]. (4) K iF Using Eqs.(6-8), it is easy to shown that, when b and f / are set to zero. in Eqs.(3) and (4), kc / is the acoustic wave number, HCM 1 1 f is the frequency, c is the speed of sound, is the () (14) KKrf structure constant or tortusotity, is the pore fluid The result states that the compressibility is a linear viscosity, is the permeability. function of the concentration of the particles in a suspension fs(1 ) (5) as assumed by Urick in 01001-p.2 ICMM 2016 2 22 2 ˄˅-()kHsf kH sff (15) 2 f ˄˅-()kH2 kH22 sf fsf (16) iF 2 + f Using Eqs.(15) and (16)ˈa second-order equation for the wave number k can be found. This solution and the relation from Eq.(3-4) that kc=/ can be used to find that 2 () k 2 eff (17) H where iF (1) (1) Figure.2 The real (solid curve) and imaginary (dot-dashed) sf f parts of the effective density given in Eq.(12) for the MRFs in ()Table 1. eff() f iF (1 ) ( 22 ) sf Table.1 The EDFM model Parameters of MRF-132DG (18) is a complex effective density. Parameters Symbol(Unit) MRF 3 Solid density ˄NJr / m ˅ 3160 3 Numerical Results and Discussion 3 Fluid density ˄NJf / m ˅ 1000 To verify the correctness of this model, the longitudinal Grain bulk 2 wave velocity and attenuation coefficient of the MRF are K Nm/ 11 modulus ˄˅r 1.26 10 calculated. Using the equations in the preceding section, the Volumetric longitudinal wave velocity and attenuation coefficient are 0.4 Specitic loss kr calculated for MRF-132DG material. Table 1 lists the Fluid bulk 2 parameters of the model for the MRF investigated which is K˄˅Nm/ 8 modulus f 9.8 10 typical of MRF-132DG manufactured by Lord Corporation. Grain d -6 All parameters of MRF in braces are either directly supplied m (m) 1 10 10 by the manufacturer or have been calculated[5]. The diameter Fluid 2 calculations for the linear equations are numerically (Ns/) m 0.07510 6 performed. For the MRF description, the fluid bulk viscosity modulus can be assumed purely elastic, because in our case Frame shear Nm2 6 G/˄˅b 0 810 the base fluid is low-viscosity silicone oil.
Load more

Recommended publications
  • Chapter 1 Metamaterials and the Mathematical Science
    CHAPTER 1 METAMATERIALS AND THE MATHEMATICAL SCIENCE OF INVISIBILITY André Diatta, Sébastien Guenneau, André Nicolet, Fréderic Zolla Institut Fresnel (UMR CNRS 6133). Aix-Marseille Université 13397 Marseille cedex 20, France E-mails: [email protected];[email protected]; [email protected]; [email protected] Abstract. In this chapter, we review some recent developments in the field of photonics: cloaking, whereby an object becomes invisible to an observer, and mirages, whereby an object looks like another one (say, of a different shape). Such optical illusions are made possible thanks to the advent of metamaterials, which are new kinds of composites designed using the concept of transformational optics. Theoretical concepts introduced here are illustrated by finite element computations. 1 2 A. Diatta, S. Guenneau, A. Nicolet, F. Zolla 1. Introduction In the past six years, there has been a growing interest in electromagnetic metamaterials1 , which are composites structured on a subwavelength scale modeled using homogenization theories2. Metamaterials have important practical applications as they enable a markedly enhanced control of electromagnetic waves through coordinate transformations which bring anisotropic and heterogeneous3 material parameters into their governing equations, except in the ray diffraction limit whereby material parameters remain isotropic4 . Transformation3 and conformal4 optics, as they are now known, open an unprecedented avenue towards the design of such metamaterials, with the paradigms of invisibility cloaks. In this review chapter, after a brief introduction to cloaking (section 2), we would like to present a comprehensive mathematical model of metamaterials introducing some basic knowledge of differential calculus. The touchstone of our presentation is that Maxwell’s equations, the governing equations for electromagnetic waves, retain their form under coordinate changes.
    [Show full text]
  • Plasmonic and Metamaterial Structures As Electromagnetic Absorbers
    Plasmonic and Metamaterial Structures as Electromagnetic Absorbers Yanxia Cui 1,2, Yingran He1, Yi Jin1, Fei Ding1, Liu Yang1, Yuqian Ye3, Shoumin Zhong1, Yinyue Lin2, Sailing He1,* 1 State Key Laboratory of Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou 310058, China 2 Key Lab of Advanced Transducers and Intelligent Control System, Ministry of Education and Shanxi Province, College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan, 030024, China 3 Department of Physics, Hangzhou Normal University, Hangzhou 310012, China Corresponding author: e-mail [email protected] Abstract: Electromagnetic absorbers have drawn increasing attention in many areas. A series of plasmonic and metamaterial structures can work as efficient narrow band absorbers due to the excitation of plasmonic or photonic resonances, providing a great potential for applications in designing selective thermal emitters, bio-sensing, etc. In other applications such as solar energy harvesting and photonic detection, the bandwidth of light absorbers is required to be quite broad. Under such a background, a variety of mechanisms of broadband/multiband absorption have been proposed, such as mixing multiple resonances together, exciting phase resonances, slowing down light by anisotropic metamaterials, employing high loss materials and so on. 1. Introduction physical phenomena associated with planar or localized SPPs [13,14]. Electromagnetic (EM) wave absorbers are devices in Metamaterials are artificial assemblies of structured which the incident radiation at the operating wavelengths elements of subwavelength size (i.e., much smaller than can be efficiently absorbed, and then transformed into the wavelength of the incident waves) [15]. They are often ohmic heat or other forms of energy.
    [Show full text]
  • Metamaterial Waveguides and Antennas
    12 Metamaterial Waveguides and Antennas Alexey A. Basharin, Nikolay P. Balabukha, Vladimir N. Semenenko and Nikolay L. Menshikh Institute for Theoretical and Applied Electromagnetics RAS Russia 1. Introduction In 1967, Veselago (1967) predicted the realizability of materials with negative refractive index. Thirty years later, metamaterials were created by Smith et al. (2000), Lagarkov et al. (2003) and a new line in the development of the electromagnetics of continuous media started. Recently, a large number of studies related to the investigation of electrophysical properties of metamaterials and wave refraction in metamaterials as well as and development of devices on the basis of metamaterials appeared Pendry (2000), Lagarkov and Kissel (2004). Nefedov and Tretyakov (2003) analyze features of electromagnetic waves propagating in a waveguide consisting of two layers with positive and negative constitutive parameters, respectively. In review by Caloz and Itoh (2006), the problems of radiation from structures with metamaterials are analyzed. In particular, the authors of this study have demonstrated the realizability of a scanning antenna consisting of a metamaterial placed on a metal substrate and radiating in two different directions. If the refractive index of the metamaterial is negative, the antenna radiates in an angular sector ranging from –90 ° to 0°; if the refractive index is positive, the antenna radiates in an angular sector ranging from 0° to 90° . Grbic and Elefttheriades (2002) for the first time have shown the backward radiation of CPW- based NRI metamaterials. A. Alu et al.(2007), leaky modes of a tubular waveguide made of a metamaterial whose relative permittivity is close to zero are analyzed.
    [Show full text]
  • Dynamic Simulation of a Metamaterial Beam Consisting of Tunable Shape Memory Material Absorbers
    vibration Article Dynamic Simulation of a Metamaterial Beam Consisting of Tunable Shape Memory Material Absorbers Hua-Liang Hu, Ji-Wei Peng and Chun-Ying Lee * Graduate Institute of Manufacturing Technology, National Taipei University of Technology, Taipei 10608, Taiwan; [email protected] (H.-L.H.); [email protected] (J.-W.P.) * Correspondence: [email protected]; Tel.: +886-2-8773-1614 Received: 21 May 2018; Accepted: 13 July 2018; Published: 18 July 2018 Abstract: Metamaterials are materials with an artificially tailored internal structure and unusual physical and mechanical properties such as a negative refraction coefficient, negative mass inertia, and negative modulus of elasticity, etc. Due to their unique characteristics, metamaterials possess great potential in engineering applications. This study aims to develop new acoustic metamaterials for applications in semi-active vibration isolation. For the proposed state-of-the-art structural configurations in metamaterials, the geometry and mass distribution of the crafted internal structure is employed to induce the local resonance inside the material. Therefore, a stopband in the dispersion curve can be created because of the energy gap. For conventional metamaterials, the stopband is fixed and unable to be adjusted in real-time once the design is completed. Although the metamaterial with distributed resonance characteristics has been proposed in the literature to extend its working stopband, the efficacy is usually compromised. In order to increase its adaptability to time-varying disturbance, several semi-active metamaterials have been proposed. In this study, the incorporation of a tunable shape memory alloy (SMA) into the configuration of metamaterial is proposed. The repeated resonance unit consisting of SMA beams is designed and its theoretical formulation for determining the dynamic characteristics is established.
    [Show full text]
  • Simulating Twistronics in Acoustic Metamaterials
    Simulating twistronics in acoustic metamaterials S. Minhal Gardezi,1 Harris Pirie,2 Stephen Carr,3 William Dorrell,2 and Jennifer E. Hoffman1, 2, ∗ 1School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA 2Department of Physics, Harvard University, Cambridge, MA, 02138, USA 3Brown Theoretical Physics Center and Department of Physics, Brown University, Providence, RI, 02912-1843, USA (Dated: March 24, 2021) Twisted van der Waals (vdW) heterostructures have recently emerged as a tunable platform for studying correlated electrons. However, these materials require laborious and expensive effort for both theoretical and experimental exploration. Here we numerically simulate twistronic behavior in acoustic metamaterials composed of interconnected air cavities in two stacked steel plates. Our classical analog of twisted bilayer graphene perfectly replicates the band structures of its quantum counterpart, including mode localization at a magic angle of 1:12◦. By tuning the thickness of the interlayer membrane, we reach a regime of strong interlayer tunneling where the acoustic magic angle appears as high as 6:01◦, equivalent to applying 130 GPa to twisted bilayer graphene. In this regime, the localized modes are over five times closer together than at 1:12◦, increasing the strength of any emergent non-linear acoustic couplings. INTRODUCTION cate, acoustic metamaterials have straightforward gov- erning equations, continuously tunable properties, fast 1 Van der Waals (vdW) heterostructures host a di- build times, and inexpensive characterization tools, mak- verse set of useful emergent properties that can be cus- ing them attractive testbeds to rapidly explore their tomized by varying the stacking configuration of sheets quantum counterparts. Sound waves in an acoustic meta- of two-dimensional (2D) materials, such as graphene, material can be reshaped to mimic the collective mo- other xenes, or transition-metal dichalcogenides [1{4].
    [Show full text]
  • Recent Advances in Acoustic Metamaterials for Simultaneous Sound Attenuation and Air Ventilation Performances
    Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 27 July 2020 doi:10.20944/preprints202007.0521.v2 Peer-reviewed version available at Crystals 2020, 10, 686; doi:10.3390/cryst10080686 Review Recent advances in acoustic metamaterials for simultaneous sound attenuation and air ventilation performances Sanjay Kumar1,* and Heow Pueh Lee1 1 Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore; [email protected] * Correspondence: [email protected] (S.K.); [email protected] (H.P.Lee) Abstract: In the past two decades, acoustic metamaterials have garnered much attention owing to their unique functional characteristics, which is difficult to be found in naturally available materials. The acoustic metamaterials have demonstrated to exhibit excellent acoustical characteristics that paved a new pathway for researchers to develop effective solutions for a wide variety of multifunctional applications such as low-frequency sound attenuation, sound wave manipulation, energy harvesting, acoustic focusing, acoustic cloaking, biomedical acoustics, and topological acoustics. This review provides an update on the acoustic metamaterials' recent progress for simultaneous sound attenuation and air ventilation performances. Several variants of acoustic metamaterials, such as locally resonant structures, space-coiling, holey and labyrinthine metamaterials, and Fano resonant materials, are discussed briefly. Finally, the current challenges and future outlook in this emerging field
    [Show full text]
  • Theoretical Study of Subwavelength Imaging by Acoustic Metamaterial
    Theoretical study of subwavelength imaging by acoustic metamaterial slabs Ke Deng1,2, Yiqun Ding1, Zhaojian He1, Heping Zhao2, Jing Shi1, and Zhengyou 1,a) Liu 1Key Lab of Acoustic and Photonic materials and devices of Ministry of Education and Department of Physics, Wuhan University, Wuhan 430072, China 2Department of Physics, Jishou University, Jishou 416000, Hunan, China We investigate theoretically subwavelength imaging by acoustic metamaterial slabs immersed in the liquid matrix. A near-field subwavelength image formed by evanescent waves is achieved by a designed metamaterial slab with negative mass density and positive modulus. A subwavelength real image is achieved by a designed metamaterial slab with simultaneously negative mass density and modulus. These results are expected to shed some lights on designing novel devices of acoustic metamaterials. a)To whom all correspondence should be addressed, e-mail address is [email protected] 1 I. INTRODUCTION Recent advances in electromagnetic (EM) metamaterials (MMs)1 provide the foundation for realizing many intriguing phenomena, such as inverse Doppler Effect,2 negative refraction,3 and amplification of evanescent waves.4 These phenomena can be utilized to design novel EM devices. Pendry found that, as the combined result of negative refraction and amplification of evanescent waves, a MM slab with effective permittivityε =−1 and permeability μEM = −1 can focus both the propagating and evanescent waves of a point source into a perfect image.5 Thereby such a slab device has been referred as the perfect lens. Pendry’s perfect lens stimulated lots of research interests due to the great significance of subwavelength imaging in various applications (see the ref.
    [Show full text]
  • Realization of a Thermal Cloak–Concentrator Using a Metamaterial
    www.nature.com/scientificreports OPEN Realization of a thermal cloak– concentrator using a metamaterial transformer Received: 2 November 2017 Ding-Peng Liu, Po-Jung Chen & Hsin-Haou Huang Accepted: 23 January 2018 By combining rotating squares with auxetic properties, we developed a metamaterial transformer Published: xx xx xxxx capable of realizing metamaterials with tunable functionalities. We investigated the use of a metamaterial transformer-based thermal cloak–concentrator that can change from a cloak to a concentrator when the device confguration is transformed. We established that the proposed dual- functional metamaterial can either thermally protect a region (cloak) or focus heat fux in a small region (concentrator). The dual functionality was verifed by fnite element simulations and validated by experiments with a specimen composed of copper, epoxy, and rotating squares. This work provides an efective and efcient method for controlling the gradient of heat, in addition to providing a reference for other thermal metamaterials to possess such controllable functionalities by adapting the concept of a metamaterial transformer. Te concept of controlling energy can be traced back to the pioneering proposals by Pendry1 and Leonhardt2, whose approaches to cloaking provided means of manipulating electromagnetic waves. Following their research, eforts have been devoted to modeling and designing coordinate transformation-based metamaterials, also known as thermal metamaterials3–5, in the feld of thermodynamics. Owing to the unconventional nature of thermal metamaterials, various applications such as the thermal cloak6–14, thermal concentrator15–17, thermal inverter18–20 and thermal illusion21–24 have been proposed. Recently, thermoelectric components25 have ofered a method for actively controlling heat fux.
    [Show full text]
  • High Dielectric Permittivity Materials in the Development of Resonators Suitable for Metamaterial and Passive Filter Devices at Microwave Frequencies
    ADVERTIMENT. Lʼaccés als continguts dʼaquesta tesi queda condicionat a lʼacceptació de les condicions dʼús establertes per la següent llicència Creative Commons: http://cat.creativecommons.org/?page_id=184 ADVERTENCIA. El acceso a los contenidos de esta tesis queda condicionado a la aceptación de las condiciones de uso establecidas por la siguiente licencia Creative Commons: http://es.creativecommons.org/blog/licencias/ WARNING. The access to the contents of this doctoral thesis it is limited to the acceptance of the use conditions set by the following Creative Commons license: https://creativecommons.org/licenses/?lang=en High dielectric permittivity materials in the development of resonators suitable for metamaterial and passive filter devices at microwave frequencies Ph.D. Thesis written by Bahareh Moradi Under the supervision of Dr. Juan Jose Garcia Garcia Bellaterra (Cerdanyola del Vallès), February 2016 Abstract Metamaterials (MTMs) represent an exciting emerging research area that promises to bring about important technological and scientific advancement in various areas such as telecommunication, radar, microelectronic, and medical imaging. The amount of research on this MTMs area has grown extremely quickly in this time. MTM structure are able to sustain strong sub-wavelength electromagnetic resonance and thus potentially applicable for component miniaturization. Miniaturization, optimization of device performance through elimination of spurious frequencies, and possibility to control filter bandwidth over wide margins are challenges of present and future communication devices. This thesis is focused on the study of both interesting subject (MTMs and miniaturization) which is new miniaturization strategies for MTMs component. Since, the dielectric resonators (DR) are new type of MTMs distinguished by small dissipative losses as well as convenient conjugation with external structures; they are suitable choice for development process.
    [Show full text]
  • Metamaterials for Electromagnetic and Thermal Waves
    Metamaterials for electromagnetic and thermal waves 1 1,2 1,3 1 Erin Donnelly , Antoine Durant , Célia Lacoste , Luigi La Spada 1School of Engineering and the Built Environment, Edinburgh Napier University, Edinburgh, United Kingdom 2IUT1, Université Grenoble Alpes, Grenoble, France 3INP-ENSEEIHT, University of Toulouse, Toulouse, France [email protected] Abstract— In the last decade, electromagnetic is of great interest in any industrial applications. Moreover, metamaterials, thanks to their exotic properties and the unsolved issues are still present: significant presence of possibility to control electromagnetic waves at will, become losses, narrow bandwidth, material properties difficult to crucial building blocks to develop new and advanced technologies in several practical applications. Even though achieve, complexity in both design and manufacturing. until now the metamaterial concept has been mostly associated Therefore, in this paper, we model, design and fabricate a with electromagnetism and optics; the same concepts can be multi-functional metamaterial able to control amplitude and also applied to other wave phenomena, such as phase of both electromagnetic and thermal wave. thermodynamics. For this reason, here the aim is to realize a The paper is organized as follows: (i) in the modeling multi-functional metamaterial able to control and manipulate section, by using field theory, we evaluate the metamaterial simultaneously both electromagnetic and thermal waves. fundamental parameters: electric permittivity ε and thermal
    [Show full text]
  • Realization of an All-Dielectric Zero-Index Optical Metamaterial
    Realization of an all-dielectric zero-index optical metamaterial Parikshit Moitra1†, Yuanmu Yang1†, Zachary Anderson2, Ivan I. Kravchenko3, Dayrl P. Briggs3, Jason Valentine4* 1Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, Tennessee 37212, USA 2School for Science and Math at Vanderbilt, Nashville, TN 37232, USA 3Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA 4Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37212, USA †these authors contributed equally to this work *email: [email protected] Metamaterials offer unprecedented flexibility for manipulating the optical properties of matter, including the ability to access negative index1–4, ultra-high index5 and chiral optical properties6–8. Recently, metamaterials with near-zero refractive index have drawn much attention9–13. Light inside such materials experiences no spatial phase change and extremely large phase velocity, properties that can be applied for realizing directional emission14–16, tunneling waveguides17, large area single mode devices18, and electromagnetic cloaks19. However, at optical frequencies previously demonstrated zero- or negative- refractive index metamaterials require the use of metallic inclusions, leading to large ohmic loss, a serious impediment to device applications20,21. Here, we experimentally demonstrate an impedance matched zero-index metamaterial at optical frequencies based on purely dielectric constituents. Formed from stacked silicon rod unit cells, the metamaterial possesses a nearly isotropic low-index response leading to angular selectivity of transmission and directive emission from quantum dots placed within the material. Over the past several years, most work aimed at achieving zero-index has been focused on epsilon-near-zero metamaterials (ENZs) which can be realized using diluted metals or metal waveguides operating below cut-off.
    [Show full text]
  • Finite-Element Design of Metamaterial Beams For
    FINITE-ELEMENT DESIGN OF METAMATERIAL BEAMS FOR BROADBAND WAVE ABSORPTION _______________________________________ A Thesis presented to the Faculty of the Graduate School at the University of Missouri-Columbia _______________________________________________________ In Partial Fulfillment of the Requirements for the Degree Master of Science _____________________________________________________ by SHUYI JIANG Dr. P. Frank Pai, Thesis Supervisor MAY 2015 The undersigned, appointed by the Dean of the Graduate School, have examined the thesis entitled FINITE-ELEMENT DESIGN OF METAMATERIAL BEAMS FOR BROADBAND WAVE ABSORPTION Presented by Shuyi Jiang A candidate for the degree of Master of Science And hereby certify that in their opinion it is worthy of acceptance. Professor P. Frank Pai Professor Steven Neal Professor Stephen Montgomery-Smith ACKNOWLEDGEMENTS I would like to express my deepest appreciation to my advisor Dr. P. Frank Pai. Without his patient guidance, I wouldn’t have grown as a good researcher. His continuous encouragement and valuable suggestions on my thesis work meant a lot to me. Also I would like to thank my committee members, Dr. Steven Neal and Dr. Stephen Montgomery-Smith, for serving on my thesis committee and providing me assistance when I have difficulties. I would also like to extend my thanks to Dr. Hao Peng, Xuewei Ruan, Haoguang Deng, Yiqing Wang, Jamie Lamont and all my labmates. They helped my study and gave me confidence to reach the goal. Thanks to all the staff in the Mechanical and Aerospace Engineering Department for their hard work for me during my study at the University of Missouri. Finally, special thanks to my family for their mental and financial support through my life.
    [Show full text]