Thermal Radiation Research Articles

Self-Thermal Management in Filtered Selenium-Terminated MXene Films for Flexible Safe Batteries.

Li-ion batteries with superior interior thermal management are crucial to prevent thermal runaway and ensure safe, long-lasting operation at high temperatures or during rapid discharging and charging. Typically, such thermal management is achieved by focusing on the separator and electrolyte. Here, the study introduces a Se-terminated MXene free-standing electrode with exceptional electrical conductivity and low infrared emissivity, synergistically combining high-rate capacity with reduced heat radiation for safe, large, and fast Li+ storage. This is achieved through a one-step organic Lewis acid-assisted gas-phase reaction and vacuum filtration. The Se-terminated Nb2Se2C outperformed conventional disordered O/OH/F-terminated materials, enhancing Li+-storage capacity by ≈1.5 times in the fifth cycle (221 mAh·g-1 at 1 A·g-1) and improving mid-infrared adsorption with low thermal radiation. These benefits result from its superior electrical conductivity, excellent structural stability, and high permittivity in the infrared region. Calculations further reveal that increased permittivity and conductivity along the z-direction can reduce heat radiation from electrodes. This work highlights the potential of surface groups-terminated layered material-based free-standing flexible electrodes with self-thermal management ability for safe, fast energy storage.

Investigating radiative heat transfer, varied wall thickness, and slip effects on Casson nanofluid flow over a stretched sheet with heat source

ABSTRACT Understanding the intricate interplay between variable fluid properties such as slip and thermal conductivity when flowing over porous surfaces is of utmost importance for a wide range of engineering applications. This investigation delves into this uncharted territory, connecting the analytical capabilities of HAM (Homotopy Analysis Method) to reveal captivating insights into the impact of these variables on the dynamics of Casson nanofluid flow. Besides, we documented the flow aspects which include thermal radiation, heat source, variable wall thickness and chemical reaction. We alter the partial differential flow-related conditions into nonlinear ordinary ones employing the similarity transformation approach. Then, using a popular semi-analytical technique known as the Homotopy Analysis Method (HAM), we were able to untangle them. This method yields to power series solutions to nonlinear differential equations. To illustrate the impact of the velocity, temperature and concentration profiles, parametric research has been done using tables and diagrams. In the limiting sense, the numerical results of our methodology are in great association with the outcomes of previous research. Finally, it is noted that higher values of the velocity slip parameter cause an enhancement in fluid velocity, while escalating values of the thermal slip parameter cause a decline in temperature distribution.

Enhanced Far-Field Thermal Radiation through a Polaritonic Waveguide

Enhanced Far-Field Thermal Radiation through a Polaritonic Waveguide

Dynamically tunable terahertz multi-band perfect absorber based on photosensitive silicon

Abstract A tunable narrowband terahertz absorber is proposed based on the photosensitive characteristics of silicon. When silicon is insulating without the pump beam, the absorber realizes three-frequency absorption at 0.731 THz, 1.145 THz, and 1.546 THz with absorptivity of 99.43%, 99.99%, and 99.98%, respectively. When the silicon is excited by the pump beam, it is conducting, and the absorber realizes double-frequency absorption at 0.852 THz, 1.536 THz, with 99.99% and 99.31%. The impedance matching theory explains the perfect absorption, and the electric field and surface current distributions are further discussed to elaborate the physical mechanisms. In addition, the effect of geometric parameters on the absorptivity is discussed. The absorber exhibits wide-angle absorption characteristics when light is polarized along the y-direction, and the absorptivity exhibits weak dependence on the polarization angle.The proposed absorber has promising applications in electromagnetic cloaking, narrow-band thermal radiation, and optoelectronic detection.

Non-linear thermal radiation and heat transfer effect on MHD flow of a micropolar fluid through a porous medium

Non-linear thermal radiation and heat transfer effect on MHD flow of a micropolar fluid through a porous medium

Numerical modeling of mixed convective nanofluid flow with fractal stochastic heat and mass transfer using finite differences

This study presents the first comprehensive numerical simulation of heat and mass transfer in fractal-like mixed convective nanofluid flows. The flow of non-Newtonian nanofluids over flat and oscillating sheets is modelled mathematically, and a finite difference scheme is used to solve this model. The two-stage scheme can tackle fractal and fractal stochastic mathematical models of partial differential equations. The consistency in the mean square is proved, and Fourier series stability analysis is adopted to find stability conditions for fractal stochastic partial differential equation. The scheme is applied to solve the unsteady Casson nanofluid flow over the flat and oscillatory sheet, which affects thermal radiation, heat source, and chemical reaction. The existence of the solution is also provided for the Navier-Stokes equation of the considered flow model using fractal time derivative. The graph illustrates that the proposed fractal technique achieves faster convergence than the Crank-Nicolson approach. Applications in energy systems, materials science, and environmental engineering are just a few of the domains that could benefit from a better understanding of mixed convective nanofluid flows with fractal features, and that is what this research study hopes to accomplish. Scientists and engineers may better develop efficient and environmentally friendly systems by simulating and analyzing these complicated processes with the suggested finite difference technique.

Thermal Marangoni convection in two-phase quadratic convective flow of dusty MHD trihybrid nanofluid with non-linear heat source

The current study examines the effect of heat generation on thermal Marangoni convective boundary layer flow of dusty trihybrid nanofluid across a flat surface with thermal radiation and non-linear mixed convection. We consider, two phase dusty liquid model with non-linear heat generation. The fluctuation of surface tension gradients leads to the discovery of Marangoni convection. It can be used for growing crystals, drying silicon wafers, stabilising soap films, and wielding. The main objective of this study is to ascertain the trihybrid nanofluid thermal mobility. A trihybrid nanofluid consisting of magnesium oxide (Mgo), titanium oxide (TiO2), silver (Ag) and water as the base fluid is used. This model can improve the efficiency and dependability of thermal systems in a variety of applications by helping to optimize heat transfer processes in materials processing, electronics cooling, and the creation of cutting-edge cooling technologies in energy systems. The existing PDEs are converted into nonlinear ODEs via similarity variables. The nonlinear ODEs are then solved numerically using shooting technique (RKF-45th approach). When the Marangoni convection parameter rises, higher surface tension gradients lead to stronger induced flows and more efficient heat transfer inside the liquid. As the temperature profiles of the dust and fluid phases drop, the distribution of these characteristics in the liquid becomes more homogeneous.

Williamson MHD Nanofluid Flow via a Porous Exponentially Stretching Sheet with Bioconvective Fluxes

The recent study concentrates on magnetohydrodynamics (MHD). Williamson fluid drifts over an exponentially extending sheet. The porous medium is also crucial to improving thermal efficiency. The flow pattern model considers the inspirations of Joule heating, heat generation, viscous dissipation, and thermal radiation. This study also comprises the activation energy, bio-convectional, and gyrotactic microorganism phenomena. Furthermore, the Brownian and thermophoresis effects of nanoparticles are taken into consideration. Using proper similarity transformation, PDEs of the impetus, temperature, concentricity, motility microbe density, and boundary constraints upgrade into a non-linearly ordinary differential equations (ODEs) mode. Using MATLAB, transformed non-dimensional ODEs are dealt with using shooting procedures and results of significant physical strictures using a built-in bvp4c solver. Finally, it is elaborated and briefly explored numerically and visually can find interesting physical strictures versus the velocity gradient, temperature gradient, solutal gradient of species, and microbes' gradient. Incorporating microorganisms and nanoparticles into Williamson fluids can create novel materials with tailored properties for diverse applications. However, it's crucial to consider stability, biocompatibility, and environmental impact when designing these advanced fluid systems.

MHD Maxwell dusty fluid in thermally stratified radiative flow with temperature-dependent thermal conductivity and Cattaneo-Christov model

It might be very important for the polymer processing industries to comprehend how Maxwell fluids behave on a stretched cylinder. Optimizing the extrusion and drawing processes can ensure the desired product qualities while avoiding faults. The objective of this study is heat transfer analysis on a Maxwell dusty fluid flow cylindrical surface with the Cattaneo-Christov concept. We immerse the cylinder in porous media, with a two-dimensional fluid regulating the flow. Our mathematical model further considers the effects of variable thermal conductivity, radiation, viscous and joule heating, magnetic field, thermal stratification, and slip velocity. Based on the presumptions,partial differential equations(PDE’s) have been used to evolve the mathematical model.Using similarity transformations, the PDE’s for heat and momentum for both phases are transformed into highly nonlinear ODE’s.The numerical results have been obtained on these ordinary differential equations by using the RKF-45 method. This issue's main characteristic is that it examines the scenario's liquid and dust phases throughout. Results are given both visually and tabularly for the major parameters over a velocity, temperature, skin friction coefficient, and Nusselt number. When we compared our method to a previously published paper, we discovered a decent match. The findings, which were obtained for our system, show that the velocity and thermal gradient of both the phases of fluid and dust behave in an opposite trend in favor of rising Maxwell parameter, where the curvature parameter makes the rise in the same manner. Furthermore, the thermal transport profiles for both phases decline for the rising thermal time relaxation parameter.

Imaging thick accretion disks and jets surrounding black holes

Based on the horizon-scale magnetofluid model developed in [1], we investigate the millimeter-wave images of a geometrically thick accretion disk or a funnel wall, i.e., the magnetofluid that encloses the base of the jet region, around a Kerr black hole. By employing the numerical method to solve the null geodesic and radiative transfer equations, we obtain the optical appearances at various observational angles and frequencies, generated by the thermal synchrotron radiation within the magnetofluid. For the thick disk, we specifically examine the impact of emission anisotropy on images, concluding that anisotropic synchrotron radiation could play an important role in the observability of the photon ring. For the funnel wall, we find that both the outflow and inflow funnel walls exhibit annular structures on the imaging plane. The outflow funnel wall yields a brighter primary image than the photon ring, whereas the inflow one does not. Based on our investigation, the inflow funnel wall model can not be ruled out by current observations of M87*.

Multimodal aircraft flight altitude inversion from SDGSAT-1 thermal infrared data

Accurately detecting and localizing high-speed aircraft is significant for monitoring global flight activities, conducting searches, and performing emergency rescues. Typically, the spatial position of an air target is obtained through active communication or multi-satellite observation. Here, we propose a multimodal flight altitude inversion method using a single thermal infrared payload (SDGSAT-1 TIS). Space-based longwave thermal infrared is a passive detection method that can measure the surface thermal radiation of objects and capture radiation differences caused by flying aircraft against the background, thereby providing an opportunity for their detection and location. Considering geographic location, time, climate, and aircraft size, we establish a framework to integrate the radiation transmission model with three-spectral-band remote sensing data. This proposed framework elucidates the relationship between flight altitude and top-of-atmosphere radiance, realizing the inversion from thermal infrared remote sensing images to altitude. Validated on 100 aircraft, the proposed framework achieved an average altitude measurement accuracy of 0.508 km compared with Flightradar24. This research provides a unique solution for the all-time passive localization of air targets.

Dissipative processes at the acoustic horizon

Abstract A transonic fluid flow generates an acoustic hole that is the hydrodynamic analogue of a gravitational black hole. Acoustic holes emit a detectable thermal radiation of phonons at a characteristic Hawking temperature. The crucial concept is that the spontaneous phonon emission at the horizon produces an irreversible heat increase at the expense of the bulk fluid kinetic energy. We show that such process can be described in terms of \textit{effective} shear and bulk viscosities that are defined close to the horizon.
We analyze this quantum friction process by resorting to a general kinetic theory approach as well as by the specific description of phonon emission as a tunneling process. The celebrated Kovtun, Son and Starinets (KSS) universal lower bound $\eta /s = 1 / 4 \pi $ of the shear viscosity coefficient to entropy density ratio, readily follows, and is extended to the longitudinal bulk viscosity at the horizon. We come to the same saturation of the KSS bound after considering the shear viscosity arising from a perturbation of the background metric at the acoustic horizon providing a -- in principle testable -- realization of the so called black hole \textit{membrane paradigm}.

Dynamically manipulating long-wave infrared polarized thermal radiation by a vanadium dioxide metasurface.

Dynamically manipulating the spectra and polarization properties of thermal radiation is the key to counter an infrared polarization imaging system (IPIS) under the different background environments. In this Letter, we propose a phase-change metasurface thermal emitter (PCMTE) composed of vanadium dioxide (VO2) dipole antenna arrays to dynamically manipulate polarized radiation spectra in the long-wave infrared (LWIR) region of 8-14 µm. During the thermally induced and reversible insulator-to-metal transition (IMT) in VO2, by simulating the LWIR images at different polarization angles for the PCMTE and background plates, the PCMTE can realize dynamically tunable LWIR camouflage; then, their degree of linear polarization (DoLP) can be calculated, which can demonstrate that the PCMTE can also achieve dynamically tunable LWIR polarization camouflage at the specific radiation angles and backgrounds. Our proposed PCMTE provides an effective scheme for adaptive IR polarization camouflage.

Evaluation of Thermal Radiation Blocking Effect of Water Mist Curtain in Fire of Hazardous Material Storage Tank

In this study, the thermal radiation blocking effect of a water mist curtain in a full-scale hazardous material storage tank fire was numerically simulated. A fire dynamics simulator (FDS) was used for the numerical simulation, and the accuracy of the heat flux prediction of the FDS was verified using an earlier experimental study on a full-scale hazardous material storage tank fire. Subsequently, a water mist curtain system was installed in a full-scale hazardous material storage tank, and the effects of fire source conditions and water mist curtain characteristics on the heat flux and thermal radiation blocking rate of the water mist curtain were examined. The results of the numerical simulation showed that the water mist curtain decreased the heat flux and increased the thermal radiation blocking rate when the fire source was a tank and dike and when the nozzle had a large spray angle and a small droplet size. Near the adjacent protected tank (in the height of 2∼14 m from the ground at the nozzle installation position), the thermal radiation blocking rate of the water mist curtain was measured to be 62.5∼72.4% and 33.5∼67.4% for the tank and dike fire and the tank fire, respectively, 62.5∼72.4% and 54.4∼65.3% for the spray angles of 180° and 90°, respectively, and 62.5∼72.4% and 71.2∼83.0% for the droplet sizes of 400 and 200 µm, respectively. This study confirmed that the water mist curtain could effectively block the thermal radiation from the fire tank to the adjacent tanks during a full-scale hazardous material storage tank fire.

New insights into MHD squeezing flows of reacting-radiating Maxwell nanofluids via Wakif's–Buongiorno point of view

AbstractThis work presents a computational investigation of a squeezing nanofluid flow under the influence of thermal radiation, magnetohydrodynamics (MHD), and chemical process in a constrained parallel-wall geometry. In this study, the non-Newtonian behavior of a rate-type (Maxwell) nanofluid is captured by rheological expressions that serve as the foundation for the flow formulation. This kind of thinking makes it possible to simulate the intricate nanofluid behavior that incorporates the elastic and viscous responses, which are useful in a variety of situations related to nanofluid dynamics, rheology, and materials science. Additionally, the transport equations are modeled properly using Wakif's–Buongiorno nanofluid model. The equations reflecting the dynamics of the nanofluid and heat-mass transport are developed based on admissible physical assumptions, such as the negligible viscous dissipation as well as the lower magnetic Reynolds number. After that, several similarity variables are introduced in these equations to get the dimensionless formulation form. Akbari–Ganji's method is used to carry out extensive computational simulations. Our results show that the increased squeezing parameters lead to larger horizontal and vertical velocities. On the other hand, the temperature showed a reverse relationship with the increasing squeezing parameters and exhibiting a cooling impact.

Kirchhoff’s Law of Thermal Radiation Has Not Been Violated

Although violation of Kirchhoff’s Law of Thermal Radiation has been claimed in a magneto-optic structure, it is shown that Kirchhoff’s Law of Thermal Radiation has not been violated, noting that violation of Kirchhoff’s Law of Thermal Radiation would imply that the Second Law of Thermodynamics has also been violated.

Shear and normal stresses of electroosmotic magnetized physiological nanofluid on curved artery with moderate Reynolds number: application on electroshock therapy

Purpose Studying the shear stress and pressure resulting on the walls of blood vessels, especially during high-pressure cases, which may lead to the explosion or rupture of these vessels, can also lead to the death of many patients. Therefore, it was necessary to try to control the shear and normal stresses on these veins through nanoparticles in the presence of some external forces, such as exposure to some electromagnetic shocks, to reduce the risk of high pressure and stress on those blood vessels. This study aims to examines the shear and normal stresses of electroosmotic-magnetized Sutterby Buongiorno’s nanofluid in a symmetric peristaltic channel with a moderate Reynolds number and curvature. The production of thermal radiation is also considered. Sutterby nanofluids equations of motion, energy equation, nanoparticles concentration, induced magnetic field and electric potential are calculated without approximation using small and long wavelengths with moderate Reynolds numbers. Design/methodology/approach The Adomian decomposition method solves the nonlinear partial differential equations with related boundary conditions. Graphs and tables show flow features and biophysical factors like shear and normal stresses. Findings This study found that when curvature and a moderate Reynolds number are present, the non-Newtonian Sutterby fluid raises shear stress across all domains due to velocity decay, resulting in high shear stress. Additionally, modest mobility increases shear stress across all channel domains. The Sutterby parameter causes fluid motion resistance, which results in low energy generation and a decrease in the temperature distribution. Originality/value Equations of motion, energy equation, nanoparticle concentration, induced magnetic field and electric potential for Sutterby nano-fluids are obtained without any approximation i.e. the authors take small and long wavelengths and also moderate Reynolds numbers.

Pulsatile flow of blood and Cattaneo Christov heat flux model in diseased arteries with variable properties

ABSTRACT The current effort is executed to interpret the heat transmission of combined stenosis and aneurysm in an artery, taking into account variable properties such as viscous dissipation and thermal radiation. We reduced the two directional energy and momentum equations to unidirectional flow by normalizing them under the mild stenotic assumption. After that, a mathematical framework for the physical problem is developed. An intricate nonlinear set of partial differential equations results from this formulation. A suitable numerical method of finite difference is employed on consequent equations to solve them. Afterward, graphical results predict the region of flow and the influence of involved parameters is shown in pictorial form. Furthermore, these solutions are employed to test how certain parameters, like streamlines, flow rate, and wall shear stress, affect blood flow. Using streamlines, we will also observe the general behavior of blood flow patterns.

Quazinormal modes and greybody factor of black hole surrounded by a quintessence in the S-V-T modified gravity as well as shadow

The purpose of this study is to investigate the quasinormal modes (QNMs), greybody factors (GFs) and shadows in a plasma of a black hole (BH) surrounded by an exotic fluid of quintessence type in a scalar-vector-tensor modified gravity. The effects of a quintessence scalar field and the modified gravity (MOG) field on the QNM, GF, and shadow are examined. Using the sixth-order WKB approach, we investigate the QNMs of massless scalar and electromagnetic perturbations. Our findings show that as the quintessence and the MOG parameter (ϵ and α) increase, the oscillation frequencies decrease significantly. Gravitational wave damping, on the other hand, decreases with increasing ϵ and α. In addition, we obtain an analytical solution for the transmission coefficients (GF) and demonstrate that more thermal radiation reaches the observer at spatial infinity as both the ϵ and α parameters increase. We also investigate the effect of the plasma background on the BH shadow and show that as the plasma background parameter increases, the shadow radius slightly shrinks. Nevertheless, the shadow radius increases as α and ϵ increase. Particularly intriguing is the fact that increasing ϵ has a greater impact on the shadow radius than increasing α, indicating that the quintessence parameter has a greater impact than the MOG parameter.

Insight into the dynamics of bioconvective Walter’s-B nanofluid flow subjected to Cattaneo–Christov heat flux and activation energy

In order to study the implementation of the generalized magnetohydrodynamic (MHD) bioconvective aspects of the Walter’s-B fluid flows over a convectively heated stretched sheet in the presence of activation energy and numerous boundary conditions, the non-homogeneous nanofluid flow model is used. Here, the nonlinear differential equations illustrating the current nanofluid flow model of non-Newtonian fluid explicitly include the concentration of both motile microbes and solid nanoparticles. Furthermore, the associated temperature, impact of thermal radiation and the Cattaneo–Christov heat flux model are discussed. The similarity transformations are formally displayed to transfer the consequential reduction in the mathematical complexity of the existing physical situation by converting partial differential equations (PDEs) into a nonlinear associated framework of ordinary differential equations (ODEs). Furthermore, the homotopy analysis method (HAM) through the MATLAB tool is used to numerically solve the dimensionless similarity equations. The results are extremely well demonstrated. In this manner, the significant engineering procedures are more accurately and entirely estimated before being reported. The results of the fixed physical factors of velocity, temperature, concentration, and microbe concentration profiles are effectively demonstrated through multiple types of illustrations and comprehensive explanations. The principal assumption is that the greater significance of the bioconvection Lewis and Peclet numbers can lead to a drop in the microbe concentration profile. It is observed that the concentration profile is reduced with the greater value of the concentration relaxation parameter.