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Absorption and plasmon resonance of Bi-metallic core-shell nanoparticles on a dielectric substrate near an external tip
(Elsevier, 2020-01) Avsar, D.; Erturk, H.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
Absorption efficiency profiles and localized surface plasmon resonance (LSPR) wavelengths are reported for metallic core-shell nanoparticles (NPs) placed over a BK7 glass substrate. A numerical study is performed with the vectorized version of the discrete dipole approximation with surface interactions (DDA-Sl-v). Gold (Au) and silver (Ag) metallic components are used for the simulations of two different core-shell structures. Absorption enhancement and the hybrid modes of plasmon resonances of the core-shell structures are compared by using a measure that defines a size configuration. It is observed that a small volume fraction of the core sizes results in shell domination over the plasmon response. An additional study is conducted to discern the sensitivity of the refractive index of nanoparticles in different surrounding environments. With a selected core-shell size configuration of Ag-Au pairs, a significant absorption enhancement with a redshift of LSPR wavelength is observed for both Ag core-Au shell and Au core-Ag shell NPs. The absorption behavior of the bare metallic NPs and selected core-shell pairs in proximity to an external probe's tip is also analyzed. The gallium phosphide (GaP) and silicon (Si) tip usage are investigated with transverse electric (TE) and transverse magnetic (TM) wave polarizations. It is observed that the dominance of light polarization on the absorption enhancement of the NPs switches at different wavelengths, where the dielectric transition for tip materials occurs. These findings show the possible targeted uses of metallic core-shell nanoparticles in several areas such as nanomanufacturing, localized heating, bio-sensing, and material detection applications.
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An adaptive vent system for localized and customized thermal management in buildings
(ASME, 2020-05-01) Keskin, Cem; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar; Keskin, Cem
This paper introduces an innovative ventilation system that is capable of providing localized and customized thermal conditions in buildings. The system has diffusers with individually operable flaps that facilitate asymmetric air inlet to control air flow inside a room in an effective way. Moreover, the system involves distributed temperature sensors, a user interface, and a control unit that allows creation and management of "thermal subzones" within a room in accordance with the different preferences of occupants. As a specific case, the thermal management of a typical office in an academic building is considered. Both experimental and numerical studies were conducted to show that it is possible to achieve several degrees of temperature differences at different room locations in a transient and controllable fashion. The dynamic management of the temperature distribution in a room can prevent the waste of conditioning energy. It is shown that the system provides a practical and impactful solution by adapting to different user preferences (UPs) and by minimizing the resource use. In order to deal with the complexity of design, development, and operation of the system, it is considered as a cyber-physical-social system (CPSS). The core of the CPSS approach used here is an enhanced hybrid system modeling methodology that couples human dimension with formal hybrid dynamical modeling. Based on a coherent conceptual framing, the approach can combine the three core aspects, like cyber infrastructure, physical dynamics, and social/human interactions of modern building energy systems to accommodate the environmental challenges. Besides physics-based achievements (managing temperature distribution inside a room), the new AVS can also leverage user engagement and behavior change for energy efficiency in buildings by facilitating a new practice for occupants' interaction with heating, ventilation, and air conditioning (HVAC) system.
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Airflow characteristics and thermal comfort of air diffusers
(ASME, 2023) Eraslan, Tolga Arda; Keskin, Cem; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar; Eraslan, Tolga Arda; Keskin, Cem
Indoor environment quality control is very important for building operations as occupant of buildings spend up to 90% of their time indoors. After Covid-19 pandemic break out, indoor environment quality has become even more crucial to the society because of health concerns. Indoor Environmental Quality (IEQ) covers conditions such as air quality, lighting, thermal conditions, ergonomics inside a building and their effects on the occupant or occupants of the building. Thermal conditions and air quality are usually achieved with the mechanical or natural ventilation systems or by HVAC equipment. As buildings became more complex structures, different airflow distribution systems to be developed to fulfill such requirements. For this purpose, not only the airflow distribution systems need to be modified but also diffusers that provide which supplies/draws air to/from systems are to be improved. Detailed analysis of these subcomponents is needed to assure that such devices provide high levels of comfort effectiveness and energy efficiency. The objective of this study is to develop a comprehensive analysis for air characterization and indoor air regime of different diffusers (square diffuser, operable flap diffuser) and their effect on comfort level of occupants Fanger’s model of thermal comfort is used with CFD simulations and a tool is considered for the validation experiments. Using more than 16 thermal sensors including one on a mannequin head, on a table and at foot level, the readings were correlated by using anemometers to measure air flow at supply diffuser and at different operating levels. CFD simulations were according to different scenarios which are to provide a comparison between diffusers and understand indoor airflow regimes. The results considering the flow interaction between diffusers and surroundings showed a detailed visual illustration in CFD simulations and their relation to perceived comfort levels.
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Center for Energy, Environment and Economy From Nano to Giga - Research and Applications
(Özyeğin University, 2021-08) Mengüç, Mustafa Pınar; Saygı, Dilek; Ötkün, G. E.
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Colorization of passive radiative cooling coatings using plasmonic effects
(Elsevier, 2023-05) Pirouzfam, N.; Mengüç, Mustafa Pınar; Sendur, K.; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
Passive radiative cooling is a novel concept and is likely to be important for building and industrial energy ef-ficiency efforts, as it will significantly contribute to the reduction of thermal management costs for electronic equipment. In most studies, radiative cooling devices are not considered for their colors; although to find a large number of users, it must be attractive to designers or architects, who usually pay significant attention to aesthetic and decorative aspects of paints. Since the majority of the coatings reported in the literature are white, there is also a need to develop color-coordinated paints and coatings. Here, we propose an approach for designing a simple structure of colored radiative cooling devices assisted by a plasmonic structures. We show that they can be tuned as desired to produce different hues of colored coatings, while maintaining adequate radiative cooling power. To demonstrate the conflicting functions of color display and radiative cooling performance, we use a bowtie nanoantenna as a color-displaying structure to investigate how the structural factors affect the cooling performance and color display accordingly. We show that periodic high index-low index alternating layers (SiO2-TiO2) on top of a thin silver layer cause broadband reflection in visible and near-infrared spectrums, while to achieve narrowband absorption in the visible region, which leads to the desired colorization, the bowtie nanoantenna is utilized. We report that by changing the structural parameters of a nanoantenna, the resonance peaks are controlled to yield a narrowband absorption in the visible spectrum to create different colors. More-over, our results indicate that although adding coloration structure to a conventional radiative cooling system reduces the cooling power by around 30%, it is still reasonable high, around 60 W/m2, and is still suitable to be used for daytime radiative cooling where control over the color is needed. Acceptable cooling power while ability to control the coloration make the proposed colored radiative cooling a potential candidate to be used in various applications, both in high end buildings or for thermal management of electronic equipment.
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Computational near-field radiative transfer and nf-rt-fdtd algorithm
(Begell House Inc., 2020) Didari, A.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
Understanding the fundamentals of near-field radiative transfer is essential for future development of new sensors and energy harvesting devices. Simulations of such problems would require a coupled solution of the electromagnetic wave equations along with the expressions for thermal emission from a body at finite temperature. Versatile computational tools, which account for the intricate physics and the computational challenges of the problems, are likely to help to the future nanomanufacturing systems and processes. These simulation methodologies should be valid for one-, two-, and three-dimensional geometries with inhomogeneities and arbitrary edges and should be applicable to different materials. In this chapter, we briefly review the recent works on numerical methods used to solve the computational near-field radiative transfer (NFRT) problems. Each of these methods has its own advantages and disadvantages, and no single technique can provide the complete and robust solution for all problems at hand. Then we outline an algorithm based on the finite difference time domain (FDTD) method for one- and two-dimensional NFRT problems. For this, we discuss the details of NF-RT-FDTD algorithm and show how this approach can be applied to surfaces covered with particles as well as with thin films with inhomogeneities. We also present simulations for more complicated biomimetic structures inspired by nature for possible sensing and energy harvesting applications. © 2020 by Begell House, Inc.
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Concluding remarks and future directions
(Elsevier, 2023-01-01) Francoeur, M.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
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Coupled heat transfer analysis and experiments to evaluate the radiative cooling potential of concrete and green roofs for buildings
(Springer Nature, 2020-08) Family, Roxana; Çelik, S.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar; Family, Roxana
Improving building energy efficiency is one of the most important challenges towards the mitigation of climate change concerns. Buildings use significant amount of energy for cooling loads. Development of new night-time and day-time radiative cooling modalities by roofs is essential for reducing the energy consumption during the summer months. If a surface is desired to be kept cool while exposed to the sun, it should have (i) the maximum reflection of solar energy at visible wavelength range, and (ii) the maximum radiative emission from the surface at atmospheric radiation bands (8-13 mu m wavelength range). In this study, reinforced concrete panels and three different types of plant-covered roof layers were investigated for their potential use for passive cooling applications, including moss, cactus and green leaves. Fourier transform infrared spectroscopy (FTIR) measurements were conducted to determine the absorbance of different samples at infrared wavelengths. In addition, reverse heat leak method was used to determine the effective conductivity values (R-values). The power of cooling parameter of each sample was determined first, and after that a coupled radiation and conduction heat transfer analysis was carried out to evaluate their insulation potential. It was demonstrated that moss is a better candidate to be used as a radiative cooling material, and it is a better insulator than the other tested materials.
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Design methodology of a concentrating solar volumetric receiver
(ASME, 2023) Akba, Tufan; Baker, D.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar; Akba, Tufan
A volumetric receiver design process is proposed to respond wide range of power, outlet temperature, or mass flow rate needs. In the receiver model, concentrated solar radiation hits the inner surface cavity and heats the gaseous fluid passing through the porous media assembled between the cavity and the insulator. Porous media properties and receiver geometry are coupled in the design process to determine the best possible option. A two-step process starts with a parameter sweep to create a surrogate model. Then, gradient-based design optimization is performed using two different surrogate models to maximize the outlet air temperature for bounded design variables in receiver volume and outer surface temperature constraints. The proposed design process has the advantage of exploring more design options faster using the surrogate model and more accurate results using the base model in the plant-level simulations. The methodology is discussed by comparing the surrogate models and the model validation shows that over 95% accuracy is obtained using both surrogate models. Surrogate-based design optimization is compared as in solution time and the final results are compared with respect to the base receiver model.
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Discrete dipole approximation with surface interaction
(Elsevier, 2023-01-01) Loke, V. L. Y.; Ertürk, H.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
In this chapter, we discuss a methodology to determine absorption and scattering cross sections of particles of different size and shape placed on substrates. This approach is based on the principles of discrete dipole approximation (DDA); however, the interaction matrix between the dipoles is modified to include the effect of the semiinfinite surface by including dipole reflections represented by Sommerfeld integrals. Depending on the direction of an incident plane wave, the particle will be illuminated by the combination of the incident wave with the reflected, transmitted, or evanescent wave. In order to explore problems involving nanomanufacturing or sensing, a new DDA-SI algorithm is constructed as an open-source computational toolbox in a MATLAB environment. Later, two other algorithms (DDA-SI-v and zDDA-SI) were developed to increase the speed of calculations. All three algorithms were considered for atomic force microscopy-based manufacturing applications using dielectric and metallic nanoparticles. Examples of different cases are provided at the end of the chapter.
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Electromagnetic and light scattering XIX
(Elsevier, 2024-01) Shcherbakov, A. A.; Bi, L.; Yurkin, Maxim A.
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Impact of computational radiation transfer on science, engineering and society
(Begell House Inc., 2017) Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
In this presentation, we will present a journey on the development of physics of radiation transfer and the related computational methodologies. We will highlight many applications of radiation transfer on fundamental sciences and engineering disciplines. This talk will not be on the details of a single computational scheme, but on the impact of a fundamental area, developed over the decades by different communities, on the society in general. We will first give a historical outline about the use of optics and radiation transfer (light and heat) over the centuries. Then, we will outline a summary of computational techniques for different physical systems used in pre-and post-digital ages, and comment on how some of these areas cross-pollinated other fields.
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In memoriam: Richard J. Goldstein
(Begell House Inc., 2023) Madanan, U.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
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Investigation of soot formation of ethylene/air jet diffusion flame with rank correlated slw including ethylene and acetylene radiation
(Begell House Inc., 2023) Halvaşi, Berkay; Başol, Altuğ Melik; Mengüç, Mustafa Pınar; Ertunç, Özgür; Mechanical Engineering; BAŞOL, Altuğ Melik; MENGÜÇ, Mustafa Pınar; ERTUNÇ, Özgür; Halvaşi, Berkay
Radiation is significant, especially in sooting flames. The interaction between radiation and soot considerably affects the combustion regime. Spectral radiation models that account for the radiative effects of sooting flames are critical. This study numerically investigates the interaction between the radiation and soot formation on a sooting jet diffusion flame. A rank correlated spectral line-based weighted sum of gray gases (RC-SLW) global model is implemented in Ansys Fluent and used for the combustion modeling of a jet diffusion flame. RC-SLW model, including ethylene and acetylene radiation, shows considerable improvement in predicting soot volume fraction compared to the domain-based with single gray gas weighted sum of gray gases (WSGG) model in Ansys Fluent. Increasing the number of gray gases in the RC-SLW model from 5 to 22 reduces the error in the maximum soot volume fraction from 30% to 1%. It was found that the effect of ethylene and acetylene radiation in the RC-SLW model has a minor effect on soot formation. Simulations without the effect of ethylene and acetylene radiation in the RC-SLW model underpredict maximum soot volume fraction by 5%.
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Light, plasmonics and particles
(Elsevier, 2023) Mechanical Engineering; Mengüç, Mustafa Pınar; Francoeur, M.; MENGÜÇ, Mustafa Pınar
Light, Plasmonics and Particles focuses on the fundamental science and engineering applications of light scattering by particles, aerosols and hydrosols, and of localized plasmonics. The book is intended to be a self-contained and coherent resource volume for graduate students and professionals in the disciplines of materials science, engineering and related disciplines of physics and chemistry. In addition to chapters related to fundamental concepts, it includes detailed discussion of different numerical models, experimental systems and applications. In order to develop new devices, processes and applications, we need to advance our understanding of light-matter interactions. For this purpose, we need to have a firm grasp of electromagnetic wave phenomena, and absorption and scattering of waves by different size and shape geometrical objects. In addition, understanding of tunneling of waves based on electron and lattice vibrations and coupling with the thermal fluctuations to enhance near-field energy transfer mechanisms are required for the development of future energy harvesting devices and sensors.
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A Monte Carlo random walk-based methodology for calculation of sensitivity coefficients in inverse radiant boundary design problem
(Begell House Inc., 2023) Yıldız, Ersin; Başol, Altuğ Melik; Mengüç, Mustafa Pınar; Mechanical Engineering; BAŞOL, Altuğ Melik; MENGÜÇ, Mustafa Pınar; Yıldız, Ersin
This study presents a methodology for the solution of inverse boundary design problems involving transient heat conduction in solid objects imposed by radiant boundary condition. The inverse solution aims to find the required time-varying radiant wall temperature that provides the desired temperature histories at several selected design points inside the solid objects. Gradient-based optimization approach is employed, and a novel methodology is developed for the calculation of the sensitivity coefficients. The sensitivity coefficients are compared with the reference solution obtained from finite difference approximation. First, the inverse boundary design methodology was tested on two scenarios with known radiant wall temperature profiles. Using the true solutions of the problems, the validity of the developed methodology was verified. Next, the methodology was tested on a case where a constant cooling rate at a single design point was set as objective function. Results show that the methodology can successfully determine the required radiant wall temperature profile that fulfills the desired cooling rate.
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Near-field radiative transfer for biologically inspired structures
(Elsevier, 2023-01-01) Didari-Bader, A.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
The field of biomimetic nanophotonics has the potential to open up unprecedented pathways for the development of sophisticated and unique devices and systems as it brings different disciplines together, including biology, physics, optics, thermal sciences, design, and nanoscale manufacturing. Given the complexity of the field, it is crucial to develop the computational tools necessary to predict the interaction between different phenomena before delving into expensive laboratory studies. In this chapter, we explore biomimetic nanophotonic systems from the standpoint of thermal and computational sciences. Particularly, we focus on near-field radiative transfer for different structures by using finite-difference time domain algorithm for the solution of problems in complex geometries. We provide the results for two case studies, one inspired by the Morpho didius butterfly and the other one from neon tetra Paracheirodon innesi fish, showing that significant spectrally selective bands can be obtained. We expect that these approaches are eventually to be adapted for new manufacturing paradigms which may be useful for the development of next-generation sensors, energy harvesting devices, and radiative cooling mechanisms.
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The Ninth International Symposium on Radiative Transfer (RAD-19)
(Elsevier, 2021-09) Lemonnier, D.; Webb, B. W.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
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Overview of light, plasmonics, and particles
(Elsevier, 2023-01-01) Mengüç, Mustafa Pınar; Francoeur, M.; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
In this chapter, we present a short discussion about light and its importance in nature, human civilizations, and society, and provide some cultural discussions. We briefly mention the interconnections between electromagnetic wave propagation, absorption, scattering, plasmonics, thermal emission, and near-field radiative transfer. We also provide an overview of the chapters in the book to help the reader to start their pursuit of interdisciplinary studies of light, plasmonics, and particles.
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Preface
(Elsevier, 2023-01-01) Mengüç, Mustafa Pınar; Francoeur, M.; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
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