Thermal Radiation

The paper presents an investigation of the influence of thermal radiation and viscous dissipation on the mixed convective flow due to a vertical plate immersed in a non-Darcy porous medium saturated with a Newtonian fluid. The physical properties of the fluid are assumed to be constant. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The governing partial differential equations are transformed into a system of ordinary differential equations and solved numerically using a shooting method. The results are analyzed for the effects of various physical parameters such as viscous dissipation, thermal radiation, mixed convection parameters, and the modified Reynolds number on dynamics. The heat transfer coefficient is also tabulated for different values of the physical parameters.

This report details experimental data useful in validating radiative transfer codes involving participating media, particularly for cases involving combustion. Special emphasis is on data for pool fires. Features sought in the references are: Flame geometry and fuel that approximate conditions for a pool fire or a well-defined flame geometry and characteristics that can be completely modeled; detailed information that could be used as code input data, including species concentration and temperature profiles and associated absorption coefficients, soot morphology and concentration profiles, associated scattering coefficients and phase functions, specification of system geometry, and system boundary conditions; detailed information that could be compared against code output predictions, including measured boundary radiative energy flux distributions (preferably spectral) and/or boundary temperature distributions; and a careful experimental error analysis so that code predictions could be rationally compared with experimental measurements. Reference data were gathered from more than 35 persons known to be active in the field of radiative transfer and combustion, particularly in experimental work. A literature search was carried out using key words. Additionally, the reference lists in papers/reports were pursued for additional leads. The report presents extended abstracts of the cited references, with comments on available and missing data for code validation, and comments on reported error. A graphic for quick reference is added to each abstract that indicates the completeness of data and how well the data mimics a large-scale pool fire. The references are organized into Lab-Scale Pool Fires, Large-Scale Pool Fires, Momentum-Driven Diffusion Flames, and Enclosure Fires. As an additional aid to report users, the Tables in Appendix A show the types of data included in each reference. The organization of the tables follows that used for the abstracts.

The full-spectrum correlated-k distribution method has been shown to be exact for thermal radiation in molecular gas-particulate mixtures which obey the correlation assumption. Unfortunately, this assumption breaks down for molecular gases with strong temperature or concentration gradients. There has previously been no way to effectively quantify the model-form uncertainty introduced by the failure of the correlation assumption. This paper examines the effect of temperature gradients in CO 2 and proposes a technique to generate probability density functions for the gray-gas absorption coefficients used in the full-spectrum correlated-k distribution method. The uncertainty in the absorption coefficients may then be propagated forward to ascertain confidence intervals for important quantities such as heat flux or intensity distributions.

The article discusses ideas about the role of so-called greenhouse gases in changing the temperature of the earth's atmosphere. A detailed analysis of the essence of the problem raises questions to which the existing theory does not give a satisfactory answer. When analyzing temperature changes, we are talking about the discrepancy between the temperature of the surface layer of the atmosphere and the temperature of the earth's surface water, the inconsistency of temperature values measured by different methods, and the accuracy of averaged values. When discussing the role of greenhouse gases, the validity of choosing different bands in the spectrum for calculating absorption coefficients is considered. The role of substances that absorb infrared radiation but are not included in the IPCC list of greenhouse gases is discussed. The main questions to the existing theory are the lack of proof of the correspondence between the absorption of infrared radiation of a certain wavelength and heat absorption, as well as the lack of a satisfactory explanation for heat absorption by all gases in the atmosphere. In this regard, the existing theory of the greenhouse effect cannot be considered justified.

Observations have confirmed the formation of dust grains in the metal-rich ejecta of SN 1987A. In this paper the grain formation in the ejecta is reinvestigated on the basis of the revised hydrodynamical model and elemental composition of the ejecta, and of the theory of homogeneous nucleation and grain growth. The adopted abundance distribution in the ejecta, inferred from the behavior of the bolo metric light curve around its maximum and the early emergence of X-rays and )I-rays, results in the sequential formation of Alz0 3 , MgSi03 and Fe30 4 grains respectively in the ejecta at 1.0 M 0 :S; Mr :s;4.4 M0 as the gas cools down. In the inner region at Mr:S; 1.0 M 0 , on the other hand, the latent heat deposited during the grain growth retards the formation of dust grains. The observed enhancement of 10 Ilm flux at -day 465 after the explosion being assigned to the thermal radiation from Al z 0 3 grains formed in the ejecta, MgSi0 3 grains start to form at -day 550, and Fe30 4 grains at -day 620, and the grains cease to form at -day 730 in the region at 1.0 M 0 :s; Mr:S; 4.4 M 0' The total mass of dust grains formed in this region is -0.23 M 0' The radii of grains newly formed in the ejecta are typically -10 A for Al z 0 3 and Fe 3 0 4 , and -70 A for MgSi0 3 grains. The calculated grain radius smaller than 0.01 Ilm satisfies the constraint on the grain size in the ejecta imposed by the analysis of the blue-shifted optical lines. Comparing the observed infrared light curve with the calculated one based on both the condensation calculation and the observed 10 Ilm flux, we suggest that: 1) The condensation efficiency of dust grains in the ejecta is greater than 0.3, or the clumps occupies the fraction of at least -20% of the ejecta on the average. 2) The grain number density in the clumps is less than 5 times that of the uniform ejecta. 3) The observed infrared luminosity is attributed to the thermal radiation from dust grains in the optically thick part of the ejecta.

In this paper, we investigate numerically the flow and heat transfer characteristics of a viscous incompressible electrically conducting micropolar fluid between two infinite uniformly stretching disks, taking the radiation and viscous dissipation effects into consideration. The transformed self similar coupled ordinary differential equations are solved using quasi-linearization method. The study may be beneficial in flow and thermal control of polymeric processing.

For prediction of incident radiative heat fluxes on the furnace walls of a boiler, one of the most accurate radiation models, the zone method of analysis, has been employed to analyze radiative heat transfer in the freeboard of large pulverized fuel utility boilers. By using this model, the behavior of the temperature and heat flux within the furnace and on the heat surfaces is investigated. The existing formula for the velocity field of a turbulent jet exit from the burner orifice is used to model the velocity field of the combusted fuel from the burner. Comparing model's predictions with experimental measured radiative fluxes on the walls showed the accuracy of the method.

Open spaces in tropical climates are highly exposed to solar radiation. These conditions will influence the outdoor energy budget, leading to an increased heat island effect and reduced human thermal comfort. Trees, however, can influence the microclimate through radiation control that indirectly reduces direct radiation uptake and glare by humans and buildings. This condition affects building energy budget and human thermal comfort. This study compares the effectiveness of Mesua ferrea L. and Hura crepitans L. in shade creation and radiation modification in improving human thermal comfort. The study employed two methods: (i) a field measurement procedure and (ii) a computer-based sun-shading analysis using ECO-TECT. The results from this study indicate that both M. ferrea L. and H. crepitans L. contribute significantly to direct thermal radiation modification below their canopies. The average solar filtration under the tree canopy for M. ferrea L. was 93%, with 5% canopy transmissivity, 6.1% of leaf area index (LAI) and 35% of shade area. For H. crepitans L. the average heat filtration under the canopy was 79%, with transmissivity of 22%, LAI of 1.5 and 52% of shade area. Thus, the study found that M. ferrea L. was more significant as a thermal radiation filter than H. crepitans L., due to the former's denser foliage cover and branching habit. This significant filtration capability contributes to reduce more terrestrial radiation, cooling the ground surfaces by promoting more latent heat, reducing air temperature by promoting more evapotranspiration and effectively improves outdoor thermal comfort in tropical open spaces.

The numerical evaluation of the net radiative heat transfer rate in a single zone, non absorbing furnace enclosure is reported. In this analysis, simplified mathematical furnace model namely, the long furnace model is used to determine furnace performance. The formulation assumes some known temperature values. Thus, heat transfer equations were set up and solved numerically. A FORTRAN computer program was developed and debugged. Results obtained from this study compare favourably well with the results from the traditional graphical method. Also, the computer program developed can handle variations in furnace operating conditions, temperatures, thermal properties and dimensions.

A summary of the Low Earth Orbital Environment, its impact on the Photovoltaic Power systems of the space station and the solutions implemented to resolve the environmental concerns or issues are described. Low Earth Orbital Environment (LEO) presents several concerns to the Photovoltaic power systems of the space station. These concerns include atomic oxygen interaction with the polymeric substrate of the solar arrays, ionized environment effects on the array operating voltage, the effects of the meteoroids and debris impacts and penetration through the different layers of the solar cells and their circuits, and the high energy particle and radiation effects on the overall solar array performance. Potential solutions to some of the degrading environmental interactions that will provide the photovoltaic power system of the space station with the desired life are also summarized.

A better mechanical resistance and improved thermal conductivity, as compared to mono nanoliquids, can be attained by the ethylene glycol-based hybrid nanofluids. These fluids have substantial uses in several engineering systems. The main focus, in the recent work, is to assess the dynamics of the ethylene glycol-based hybrid nano-structured fluid via the computational fluid dynamics (CFD) and machine learning (ML) approaches. The nano-composition of single-walled carbon nanotubes (SWCNTs) and titanium dioxide (TiO 2) in the ethylene glycol causes the hybrid mixture SWCNTs-TiO 2 /EG. A CFD model, for the simulation procedure, is developed by incorporating the similarity coordinates to the governing partial differential equations. This model comprises of a dimensionless system having prime parameters of the problem. The numerical results are appraised by means of a comparison between the present and the existing results. The levenberg marquardt (LM) technique is a powerful tool to predict the flow and thermal properties. The complex correlations between the input parameters and fluid flow properties can be interpreted with the help of CFD as well as LM neural network. The results of this work might provide a basis for the design and development of highperformance heat exchangers and thermal management systems.

We present an updated and newly compiled radio-continuum data base for Macquarie/AAO/Strasbourg Hα (MASH) planetary nebulae (PNe) detected in the extant largescale 'blind' radio-continuum surveys [NRAO VLA Sky Survey (NVSS), Sydney University Molonglo Sky Survey/Molonglo Galactic Plane Surveys (SUMSS/MGPS-2) and Parkes-MIT-NRAO (PMN)] and, for a small number of MASH PNe, observed and detected in targeted radio-continuum observations. We found radio counterparts for approximately 250 MASH PNe. In comparison with the percentage of previously known Galactic PNe detected in the NVSS and MGPS-2 radio-continuum surveys and according to their position on the flux density angular diameter and the radio brightness temperature evolutionary diagrams we conclude, unsurprisingly, that the MASH sample presents the radio-faint end of the known Galactic PNe population. Also, we present radio-continuum spectral properties of a small sub-sample of MASH PNe located in the strip between declinations -30 • and -40 • , that are detected in both the NVSS and MGPS-2 radio surveys.

The ballistic limit of isotropic elastic scattering in an infinite slab of thickness L is studied using rigorous lower bounds for the transmission-time distribution. In this model particles with velocity v enter the slab normal to its face. They then scatter isotropically with mean free path A, . In the ballistic limit, where A, /L ~~, the transmission-time distribution moments (t ) might be expected to converge to those of the input distribution, properly translated in time. It is shown, however, that all moments with n )2 diverge as c"L v "A. " . Comparison between Monte Carlo simulations and rigorous, analyt- ic lower bounds for the moments show excellent agreement in the ballistic limit. It is conjectured that the anomalous asymptotic behavior of the moments is completely due to trajectories involving at most two scattering events.

The present paper investigates the effects of thermal radiation, joule heating on an unsteady hydro magnetic free convective flow of a viscous electrically conductive Newtonian and polar fluid past a semi-infinite vertical plate embedded in a porous media in the presence of heat absorption, chemical reaction, slip flow and Dufour effect. Analytical perturbation solutions are obtained for the velocity, temperature and concentration fields as well as for the skin friction coefficient, Nusselt number and Sharewood number. The results are presented in graphical forms to study the effects of various parameters.

We study under what conditions the thermal peeling is present for dissipative local and quasi-local anisotropic spherical matter configurations. Thermal peeling occurs when different signs in the velocity of fluid elements appear, giving rise to the splitting of the matter configuration. The evolution is considered in the quasi-static approximation and the matter contents are radiant, anisotropic (unequal stresses) spherical local, and quasi-local fluids. The heat flux and the associated temperature profiles are described by causal thermodynamics consistent with this approximation. It is found that both types of configurations can exhibit thermal peeling when most of the radiated energy emerges from the first half of the distribution, and thermal peeling appears to be associated with extreme astrophysical scenarios (highly relativistic and very energetic gravitational system).

When using vision systems that employ multiple spectral bandwidths, such as visible and Long-Wave Infrared (LWIR) bands, the calibration object's appearance can significantly impact the matching of common features in the images. To address this issue, a robust calibration technique is necessary to work with reflections and the degraded appearance of the calibration pattern over time. In this paper, we propose a novel stereo calibration technique that can be used for visible-thermal imaging systems for remote sensing applications (e.g., mounted on Unmanned Aerial Vehicles, UAVs). Proposed method can be used on a generic calibration pattern, and we exploit computer vision algorithms to accurately estimate the intrinsic and extrinsic parameters. The algorithm can mitigate specular reflections and contrast inversion issues that may degrade the calibration accuracy. The calibration technique is designed to be versatile as it operates also in outdoor environments, hence it can be especially useful for UAV applications since on-field re-calibration is often needed. The proposed method has been validated using two different calibration patterns and compared with state-of-the-art techniques.

Microorganisms play a vital role to understand the ecological system and so it is very important to understand the behavior of microorganism due to different parameters. In the present paper, we implement a mathematical model to understand the influence of the thermal radiation on the gyrotactic microorganism imbedded in water based nanofluid flow over a wedge. The Brownian motion and thermoforetic effects take place due to nanofluid. The governing equations based on the conservation of mass, momentum, energy, nanoparticle concentration and concentration of gyrotactic micro-organism are simplified to a set of coupled, non-linear ordinary differential equations using the similarity transformations. The transformed equations are then solved comfortably using a numerical method namely fourth order Runge-Kutta method. The numerical results accomplished in thepresent investigation are validated and are in good agreement with the prevously published results of some noteworthy researchers ...

An analysis has been carried out to examine the two-dimensional and magnetohydrodynamic (MHD) flow of thixotropic fluid over a stretched surface. The thermal radiation effect in the heat transfer is considered when the thermal conductivity is not constant. Conservation of mass, momentum and energy leads to the governing partial differential equations of the present study. The resulting equations are solved for convergent series solutions. Numerical values of the skin-friction coefficient are presented and analyzed.

We present a simple and general procedure for calculating the thermal radiation coming from any stationary metric. The physical picture is that the radiation arises as the quasiclassical tunneling of particles through a gravitational barrier. We study three cases in detail: the linear accelerating observer (Unruh radiation), the nonrotating black hole (Hawking radiation), and the rotating/orbiting observer (circular Unruh radiation). For the linear accelerating observer we obtain a thermal spectrum with the usual Unruh temperature. For the nonrotating black hole we obtain a thermal spectrum, but with a temperature twice that given by the original Hawking calculations. We discuss possible reasons for the discrepancies in temperatures as given by the two different methods. For the rotating/orbiting case the quasiclassical tunneling approach indicates that there is no thermal radiation. This result for the rotating/orbiting case has experimental implications for the experimental detect...

The Composite Infrared Spectrometer (CIRS) is a remote-sensing Fourier Transform Spectrometer (FTS) on the Cassini orbiter that measures thermal radiation over two decades in wavenumber, from 10 to 1400 cm -1 (1 mm to 7µm), with a spectral resolution that can be set from 0.5 to 15.5 cm -1 . The far infrared portion of the spectrum (10-600 cm -1 ) is measured with a polarizing interferometer having thermopile detectors with a common 4-mrad field of view (FOV). The middle infrared portion is measured with a traditional Michelson interferometer having two focal planes (600-1100 cm -1 , 1100-1400 cm -1 ). Each focal plane is composed of a 1 ×10 array of HgCdTe detectors, each detector having a 0.3-mrad FOV. CIRS observations will provide three-dimensional maps of temperature, gas composition, and aerosols/condensates of the atmospheres of Titan and Saturn with good vertical and horizontal resolution, from deep in their tropospheres to high in their mesospheres. CIRS's ability to observe atmospheres in the limb-viewing mode (in addition to nadir) offers the opportunity to

Indoor thermal environment in air conditioned spaces is most important factor while considering comfort level. We know that air distribution methods are used for comfort purpose which is important for finding the perfect indoor environment condition. If indoor conditions are satisfied, the comfort level has been determined. Some important parameter such as humidity level, air temperature and velocity, noise, indoor air quality can be taking into account for designing a thermal comfort environment. Various methods can be used numerically and experimentally to determine value of these parameter which is important for indoor thermal environment. Here theoretical review has been made for it. Design of a thermally comfortable indoor environment requires detailed information about distribution of air velocity, air temperature, relative humidity, and mean radiant temperature and about heating/cooling load in a space. In this paper we study a review on the indoor environment in a conditione...

The phenomenon of ablation is a process of thermal protection with several applications, mainly, in mechanical and aerospace engineering. Ablative thermal protection is applied using special materials (named ablative materials) externally on the surface of a structure in order to isolate it against thermal effects. The ablative phenomenon is a complex process involving phase changes with partial or total loss of the material. So the position of the boundary is initially unknown. The governing equations of the process form a non-linear system of coupled partial differential equations. The one-dimensional analysis of an ablative process on the plate is performed by using the generalized integral transform technique – GITT for solution of the system of governing equations. By application of this solution technique, the system of partial differential equations is transformed into a system of infinite ordinary differential equations that can be solved after the truncation of that system ...

The molecular ion of acetophenone is shown to undergo unimolecular dissociation to the benzoyl cation in an ICR cell at low pressures and in the vicinity of 333 K with rate constants in the range of 2 to 4 s−1. Pressure and temperature dependence of this process reveal that the process is primarily induced by absorption of thermal radiation driving ions to energies above the dissociation limit. Collisional effects also enhance this dissociation by a mechanism that attempts to restore a full Boltzmann distribution of the molecular ions.

The molecular ion of acetophenone is shown to undergo unimolecular dissociation to the benzoyl cation in an ICR cell at low pressures and in the vicinity of 333 K with rate constants in the range of 2 to 4 s−1. Pressure and temperature dependence of this process reveal that the process is primarily induced by absorption of thermal radiation driving ions to energies above the dissociation limit. Collisional effects also enhance this dissociation by a mechanism that attempts to restore a full Boltzmann distribution of the molecular ions.

International audienceIf Hydrogen is expected to be highly valuable, some improvements should be conducted, mainly regarding the storage safety. To prevent from high pressure hydrogen composite tanks bursting, the comprehension of the thermo-mechanics phenomena in the case of fire should be improved. To understand the kinetic of strength loss, the heat flux produced by fire of various intensities should be assessed. This is the objective of this real scale experimental campaign, which will allow studying in future works, the strength loss of composite high-pressure vessels in similar fire conditions to the ones determined in this study. Fire calibration tests were performed on metallic cylinder vessels. These tests with metallic cylinders are critical in the characterization of the thermal load of various fire sources (pool fire, propane gas fire, hydrogen gas fire) so as to evaluate differences related to different thermal load. Radiant panels were also used as thermal source for r...

Unsteady magneto-hydrodynamic heat and mass transfer analysis of hybrid nanofluid flow over stretching surface with chemical reaction, suction, slip effects and thermal radiation is analyzed in this problem. Combination of carbon nanotubes and silver nanoparticles are taken as hybrid nanoparticles and water is considered as base fluid. Using similarity transformation method, the governing equations are changed into system of ordinary differential equations. These equations together with boundary conditions are numerically evaluated by using finite-element method. The influence of various pertinent parameters on the profiles of fluids concentration, temperature, and velocity is calculated and the outcomes are plotted through graphs. The values of non-dimensional rates of heat transfer, mass transfer and velocity are also analyzed, and the results are depicted in tables. Temperature sketches of hybrid nanofluid intensified in both steady and unsteady cases as volume fraction of both nanoparticles rises.

This communication deliberates the time-reliant and Darcy–Forchheimer flow of water-based CNTs/gold nanoparticles past a Riga plate. In addition, nonlinear radiation, heat consumption and multiple slip conditions are considered. Entropy generation is computed through various flow parameters. A suitable transformation with symmetry variables is invoked to remodel the governing mathematical flow models into the ODE equations. The homotopy analysis scheme and MATLAB bvp4c method are imposed to solve the reduced ODE equations analytically and numerically. The impact of sundry flow variables on nanofluid velocity, nanofluid temperature, skin friction coefficient, local Nusselt number, entropy profile and Bejan number are computed and analyzed through graphs and tables. It is found that the nanofluid velocity is reduced by greater porosity and slip factors. The thickness of the thermal boundary layer increases with increasing radiation, temperature ratio, and heat consumption/generation p...

In this study, two dimensional mixed convective MHD stagnation point flow of Casson fluid past an infinite plate in porous medium is considered. Effects of thermophoresis, Brownian motion, non-linear thermal radiation, heat generation and chemical reaction are considered. The governing differential equations are modified using similarity transformation. System of ODE is solved using HAM. Effects of different vital parameters on velocity, temperature and concentration profiles are shown graphically. The numerical values of the velocity, temperature and concentration gradient are also obtained in tabular form. It is illustrated that, mixed convection parameter λ, buoyancy force parameter N, non-linear thermal radiation parameter Nr and heat generation parameter H tends to improve motion of the fluid throughout the flow field. It is also seen that, heat and mass transfer process improve with Brownian motion Nb and thermophoresis parameter Nt. Brownian motion and thermophoresis parameters have negative impacts on temperature gradient.

The objective of this paper is to investigate the effect of the addition of nanoparticles to soft tissue phantoms, aiming at the enhancement of photothermal therapy for cancer. The phantoms were made of Polyvinyl chloride-plastisol (PVC-P), with two different nanoparticles, namely, titanium dioxide nanoparticles (TiO 2 ) and silica nanoparticles (SiO 2 ). A phantom without nanoparticles and a phantom containing a thermal paste were also manufactured for comparison purposes. The PVC-P phantom is transparent to the near infrared laser light, whereas the addition of titanium dioxide nanoparticles modified the optical properties enhancing the local heating, as demonstrated through experiments with a laser-diode and an infrared camera.

In this study, we analyse the effects of thermal radiation on unsteady natural convective flow of a nanofluid past an impulsively started infinite vertical plate. The nanofluid contains heat treatable nickel chromium iron alloy (Nimonic 80A) nanoparticles with Ethylene Glycol as base fluid. The partial differential equations governing the flow are solved numerically by MATALB pde solver package. The effects of various parameters on velocity and temperature profiles, as well as Nusselt number and Skin friction coefficient are examined and presented graphically .It is found that rate of heat transfer increases by increase in thermal radiation and change of particle shape. Also we observed that the decrease in radiation parameter leads to fall the value of skin friction coefficient. Shape of nanoparticles doesn't effects velocity of the fluid.

Time-resolved optical and thermal analyses of laser diode arrays reveals temperature induced chirp and the presence of anomalous hot spots. I. INTRODUCTION An important need, especially for space-borne applications, is the early identification and rejection of laser diode arrays which may fail prematurely. Temperature has been identified as an important parameter in the performance of a Laser Diode Arrays (LDA). The lifetime of LDAs decrease exponentially with increasing temperature(1). This has led to the development of two techniques, temporally-resolved thermography, from which the time resolved temperature of the output facet of the device is measured and Temporally- resolved and Spectrally-Resolved (TSR) optical output from which the temperature of the active region of the device can be measured (2, 3). This is in addition to power monitoring on long-term burn stations. A numerical model of the thermal properties of the device has also been constructed from which the time-evolu...

An exact analytical description of the internal radiative field inside an emitting-absorbing gray semi-transparent medium enclosed in a two-dimensional parallelogram cavity is proposed. The expressions of the incident radiation and the radiative flux field are angularly and spatially discretized with a double Gauss quadrature, and the temperature field is obtained by using an iterative process. Some numerical solutions are tabulated and graphically presented as the benchmark solutions. Temperature and two components of the radiative flux are finally sketched on the whole domain. It is shown that the proposed method gives perfectly smooth results.

The present work analyzes the influence of a first-order homgeneous chemical reaction and thermal radiation on hydromagnetic free convection heat and mass transfer for a viscous fluid past a semi-infinite vertical moving porous plate embedded in a porous medium in the presence of thermal diffusion and heat generation. The fluid is considered to be a gray, absorbing-emitting but non-scattering medium, and the Rosseland approximation is used to describe the radiative heat flux in the energy equation. The plate moves with constant velocity in the direction of fluid flow while the free stream velocity is assumed to follow the exponentially increasing small perturbation law. A uniform magnetic field acts perpendicular to the porous surface, which absorbs the fluid with a suction velocity varying with time. The dimensionless governing equations for this investigation are solved analytically using two-term harmonic and non-harmonic functions. The effects of various parameters on the velocity, temperature and concentration fields as well as the skin-friction coefficient, Nusselt number and the Sherwood number are presented graphically and in tabulated forms.

is paper reports multiple slip effects on MHD unsteady flow heat and mass transfer over a stretching sheet with Soret effect; suction/injection and thermal radiation are numerically analyzed. We consider a time-dependent applied magnetic field and stretching sheet which moves with nonuniform velocity. Suitable similarity variables are used to transform governing partial differential equations into a system of coupled nonlinear ordinary differential equations. e transformed equations are then solved numerically by applying an implicit finite difference method with quasi-linearization technique. e influences of the various parameters on the velocity temperature and concentration profiles as well as on the skin friction coefficient and Sherwood and Nusselt numbers are discussed by the aid of graphs and tables.

Aims. In a previous study we suggested that the broad-band emission and variability properties of BL Lacertae can be accounted for by a double synchrotron emission component with related inverse-Compton emission from the jet, plus thermal radiation from the accretion disc. Here we investigate the matter with further data extending over a wider energy range. Methods. The GLAST-AGILE Support Program (GASP) of the whole earth blazar telescope (WEBT) monitored BL Lacertae in 2008-2009 at radio, near-IR, and optical frequencies to follow its flux behaviour. During this period, high-energy observations were performed by XMM-Newton, Swift, and Fermi. We analyse these data with particular attention to the calibration of Swift UV data, and apply a helical jet model to interpret the source broad-band variability. Results. The GASP-WEBT observations show an optical flare in 2008 February-March, and oscillations of several tenths of mag on a few-day time scale afterwards. The radio flux is only mildly variable. The UV data from both XMM-Newton and Swift seem to confirm a UV excess that is likely caused by thermal emission from the accretion disc. The X-ray data from XMM-Newton indicate a strongly concave spectrum, as well as moderate (∼4-7%) flux variability on an hour time scale. The Swift X-ray data reveal fast (interday) flux changes, not correlated with those observed at lower energies. We compare the spectral energy distribution (SED) corresponding to the 2008 low-brightness state, which was characterised by a synchrotron dominance, to the 1997 outburst state, where the inverse-Compton emission was prevailing. A fit with an inhomogeneous helical jet model suggests that two synchrotron components are at work with their self inverse-Compton emission. Most likely, they represent the radiation from two distinct emitting regions in the jet. We show that the difference between the source SEDs in 2008 and 1997 can be explained in terms of pure geometrical variations. The outburst state occurred when the jet-emitting regions were better aligned with the line of sight, producing an increase of the Doppler beaming factor. Conclusions. Our analysis demonstrates that the jet geometry can play an extremely important role in the BL Lacertae flux and spectral variability. Indeed, the emitting jet is probably a bent and dynamic structure, and hence changes in the emitting regions viewing angles are likely to happen, with strong consequences on the source multiwavelength behaviour.

The detection of a bright optical emission measured with good temporal resolution during the prompt phase makes GRB 060111B a rare event that is especially useful for constraining theories of the prompt optical emission. We discuss some interesting properties of this burst in comparison with other GRBs for which an optical peak emission has been observed.

This work examines the theoretical analysis of the nonlinear thermal radiation therapy that involves microwave heating of the hyperthermia tumor cell. The heat transfer is carried out in a porous medium and is time dependent. Non-dimensionalized variables and quantities were used as the main modeled equations alongside the Dirichlet boundary conditions for physical interpretation. The dimensionless equation accurately predicts the blood temperature distributions within the tissues, by using stable and unconditional convergent finite difference of semi-implicit type. Tumor cells death occurred due to increased cells sensitivity to non-linear thermal radiation and blood flow emanating from the hyperthermia treatment. The results showed that applying high metabolic heat of 3.97X10 5 W m -3 on tumor cells have a therapeutic effect.

In this article, we have examined the three-dimensional flow of heat and mass transport of carbon nanotube–based nanoliquid over a rotating stretchable disk. A uniform magnetic field [Formula: see text] is applied in a transverse direction to the flow of nanofluid. Moreover, we have considered carbon nanotube nanoparticles termed as single-walled carbon nanotubes within the base liquid (water). In addition, at the boundaries of current problem, the effect of velocity slip and thermal convection is deliberated. The heat transport mechanism is also incorporated thermal radiation. The pertinent strong nonlinear ordinary differential system after utilizing the appropriate variables is intended. Homotopy analysis method technique is employed to estimate the analytical results for velocities and thermal fields. For the sake of comparison, the numerical method ND-Solve solution is also obtained. The results are found to be in an excellent agreement. Various graphs have been plotted in orde...

An investigation is made for analyzing the behavior of MHD flow phenomena of a non-Newtonian fluid over a non-linear radially stretching sheet by using numerical technique. Magnetic field is considered in normal direction to the stretching sheet. With use of similarity transformations, the pdes are transformed into odes. The solution of theses odes are performed by using fourth order Runge - Kutta method along with shooting technique. The significance of different physical parameters characterizes the flow phenomena are analyzed with the use of graphs. The Jeffrey parameter  and magnetic parameter  has significant effect on velocity and temperature distribution over a non-linear stretching sheet. It is noticed that, the higher magnetic parameter results the increase in entropy generation number where the opposite nature is noticed in the case of Bejan number.  

A national combustion code (NCC) is under development under the sponsorship of NASA-Lewis Research Center. A part of this program is to develop a radiative heat transfer module to include the effects of radiative heat transfer (both gaseous and particle radiation) in the flow solution procedure. The module being developed has the capability to perform radiative heat transfer analysis in three-dimensional non-gray enclosures and includes the non-gray interaction of the multiple gaseous species, H 2 O, CO 2 , and CO respectively. It also includes models for luminous radiation from soot. The analysis procedure at present uses a finite volume methodology (FVM) in body fitted coordinates (BFC) for radiative transfer along with the weighted-sum-of-gray gases (WSGG) concept for treating the non-gray gases. This will be modified to be applicable to unstructured grids in the near future. The methodology provides the divergence of radiative heat flux at each cell of the FVM grid for inclusion in the flow solver. It also provides the radiative heat flux and intensity of radiation at each cell. The objective of this paper is to assess the methodology developed using the reacting flow test data and to validate the methodology for application to combustors.

Verification and Validation of Commercial Version of the Code Work in co-operation with ANL and other participanb to improve the models rn Verm and Validate new models within me framework of the release version of the CHAD code A stancLalone FORTRAN 90 code to calculate view factors for radiation mudel is developed at ORNL under a previous CRADA by Williams et al. (Ref, 3) This is based on the FACET m o d e developed at LLNL by Shapiro (Ref. 4). The integration to CHAD has been accomplished by another routine that computes the source terms to the energy equation. Some of the tasks, which need to be performed for the completion of tasks listed along with work plan. are: a) Evaluate the current thermal radiation algorithm as compared to others in the literature to see whether the net-radiation model is efficient and accurate enough for underhood simulations. b) Paralldize the stand-alone routine to have reducec wall-clmk times for view-factor calculations. With the use of SCALAPACK routines available and HPF compilers, this step can be easily achieved The parallelization procedure will he done using Shared Memory Parallilkation (SMP) in the beginning and later extend to Distributed Memory Parallelization (OMP) using Message Passing Interface (MPI). c) Validation and verification of the view factor calculations and if possible the validation of thermal radiation m d e l in totality coupled to CHAD or STAR-CD. d) Explore more intelligent and inbuilt approach to lump computational elements into radiation elements rather than the need to do them manually. On a same note. a provision should be provided to only deal with the most crttical elements based on criteria like (line-of-sight, surface properties like temperature & radiatiori properties). The problem being addressed is similar to the ones found in the stirdies of Computational Geometry and Radiosity in Computer Graphics. A rigorous s u m y of available literature in those fields can give enough insight addressing this problem. Work plan described above is expected to produce a working and validated thermal radiation model completely integrated into the CHAD code with possiMe migration to STAR-CD. The capability will no1 nnly b~ hetpful in studying the Underhood problem but also in any ROW where heat-transfer rates due to thermal radiation can be significant. Comparison of thermal Radiation lllkdek commonty wed: Over the past 3-4 decades thermal radiation modeling has received attentionthis is due to both the need for some applications and also the ability to incorporate thermal radiation effects with the advent of super computers The mcst popular choims for simulating radiative heat transfer are (Rsf. 1 8 2): a) Net-Radiation Modet Provides input to online routine User-Srcs and LU factors for efficient linear solver The geometric view factors can be calculated from Eq. 1. The straight way of integration IS to discretize in the following manner. , .

We study a thermo-diffusive combustion model for premixed flames propagating in reactive gaseous mixtures which contain inert dust. As observed by Joulin, radiative transfer of heat may significantly enhance the flame temperature and its propagation speed. The Joulin effect is at its most pronounced in the parameter regime where the medium is very transparent while radiative flux dominates convection. In this asymptotic regime, where in the limit the flame temperature achieves its upper bound, we determine the law that describes the relation between the propagation speed of the flame and the control parameters. Finally we present strong numerical evidence for the validity of the asymptotic analysis.

The construction of an 8-element array camera which uses tapered light pipes to couple radiation onto Ga:Ge bolometers is described. The camera is designed for broad-band thermal infrared imaging observations between 5 and 35 |xm on the Wyoming Infrared Observatory (WIRO) 2.34-m telescope. Electroforming and low-temperature casting techniques are shown to be useful for the construction of close-packed arrays. The performance of the array is discussed and a typical image taken with the camera is presented.

Scattered electromagnetic waves from material bodies of different forms contain, in an intricate way, precise information on the intrinsic, geometrical and physical properties of the objects. Scattering theories, ever deepening, aim to provide dependable interpretation and prediction to the complicated interaction of electromagnetic radiation with matter. There are well-established multiple-scattering formulations based on classical electromagnetic theories. An example is the Generalized Multi-particle Mie-solution (GMM), which has recently been extended to a special version ̶ the GMM-PA approach, applicable to finite periodic arrays consisting of a huge number (e.g., >>10 6 ) of identical scattering centers [1]. The framework of the GMM-PA is nearly complete. When the size of the constituent unit scatterers becomes considerably small in comparison with incident wavelength, an appropriate array of such small element volumes may well be a satisfactory representation of a material entity having an arbitrary structure. X-ray diffraction is a powerful characterization tool used in a variety of scientific and technical fields, including material science. A diffraction pattern is nothing more than the spatial distribution of scattered intensity, determined by the distribution of scattering matter by way of its Fourier transform [1]. Since all linear dimensions entered into Maxwell's equations are normalized by wavelength, an analogy exists between optical and X-ray diffraction patterns. A large set of optical diffraction patterns experimentally obtained can be found in the literature [e.g., 2,3]. Theoretical results from the GMM-PA have been scrutinized using a large collection of publically accessible, experimentally obtained Fraunhofer diffraction patterns. As far as characteristic structures of the patterns are concerned, theoretical and experimental results are in uniform agreement; no exception has been found so far. Closely connected with the spatial distribution of scattered intensities are cross sections, such as for extinction, scattering, absorption, and radiation pressure, as a critical type of key quantity addressed in most theoretical and experimental studies of radiative scattering. Cross sections predicted from different scattering theories are supposed to be in general agreement. For objects of irregular shape, the GMM-PA solutions can be compared with the highly flexible Discrete Dipole Approximation (DDA) [4,5] when dividing a target to no more than ~10 6 unit cells. Also, there are different ways to calculate the cross sections in the GMM-PA, providing an additional means to examine the accuracy of the numerical solutions and to unveil potential issues concerning the theoretical formulations and numerical aspects. To solve multiple scattering by an assembly of material volumes through classical theories such as the GMM-PA, the radiative properties of the component scatterers, the complex refractive index in particular, must be provided as input parameters. When using a PA to characterize a material body, this involves the use of an adequate theoretical tool, an effective medium theory, to connect Maxwell's phenomenogical theory with the atomistic theory of matter. In the atomic theory, one regards matter as composed of interacting particles (atoms and molecules) embedded in the vacuum [6]. However, the radiative properties of atomic-scaled particles are known to be substantially different from bulk materials. Intensive research efforts in the fields of cluster science and nanoscience attempt to bridge the gap between bulk and atom and to understand the transition from classical to quantum physics. The GMM-PA calculations, which place virtually no restriction on the component-particle size, might help to gain certain insight into the transition.

: An experimental analysis and computational modelling of thermal radiation from an INCONEL601 wire-mesh porous burner has been conducted. It has been found that within a bandwidth between 2 microns and 20 microns, the infrared radiation in the 2-5 microns waveband is the dominant band. Optimal operating conditions, as determined by the surface temperature and radiant intensity, are a function of the equivalence ratio and the firing rate. The location of the flame front is also influenced by these parameters. For fuel-rich mixtures the flame is usually located above the surface and the flame stability is sensitive to external perturbations. A maximum surface temperature of approximately 1223K, and a radiation intensity of 50 W/Sr, has been measured. It has also been shown that INCONEL601, despite its high emissivity, can be used as an effective radiation shield. By placing a piece of the wire-mesh in front of burning MTV pyrotechnic composition, the infrared radiation was significan...