Analytic Models for Temperature Distribution Near a Nanoantenna

2013 ◽  
Author(s):  
Casey N. Brock ◽  
Greg Walker ◽  
Zack Coppens
Keyword(s):  
Temperature Distribution ◽  
Boundary Conditions ◽  
Surface Temperature ◽  
Temperature Fields ◽  
Analytic Model ◽  
Superposition Model ◽  
Metallic Structures ◽  
Temperature Variations ◽  
Temperature Distributions ◽  
Analytic Models

Thermoplasmonic structures produce highly localized temperature fields. For simplicity, researchers often use a superposition of representative spheres to model the temperature in the non-conductive region (presumably a substrate) near the metallic structures deposited on the substrate. The superposition model provides reasonable solutions, but direct comparison to experiments is difficult because local temperature variations at the nanoscale are not accessible. Moreover, the model requires several approximations. Therefore, we compare this model to other analytic models to determine the efficacy of the superposition approach in capturing temperature distributions close to the surface of the substrate and to capture realistic boundary conditions. Results indicate that a 3D analytic model can relax approximations required for the superposition model and show that the superposition model consistently over-predicts the surface temperature.

scholarly journals Research on Flow and Temperature Fields in Aircraft Engines

2014 ◽  
Vol 8 (1) ◽  
pp. 731-738 ◽  
Author(s):  
Guochang Zhao ◽  
Daniel X. Zhao ◽  
Jing Li ◽  
Xia Du ◽  
Xianyi Tong ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Boundary Conditions ◽  
Analytical Solutions ◽  
Temperature Fields ◽  
Dimensionless Temperature ◽  
Wedge Flow ◽  
Dimensionless Velocity ◽  
Temperature Distributions ◽  
Wall Boundary Conditions

The similarity criteria which ensure the similarity between flow and temperature fields of both the lowtemperature turbine cavity model and the actual high-temperature turbine cavity are derived and then verified using numerical simulation of two different sized rotor-stator system turbine cavities. The analytical solution of threedimensional dimensionless velocity distribution and the numerical solutions of both the three-dimensional dimensionless velocity and temperature distributions of the free disk flow field are obtained. Using these solutions as a foundation, the analytical solutions of the dimensionless temperature distribution within the boundary layer of the isothermal and nonisothermal free disk model are obtained. The numerical and analytical solutions of velocity and temperature are compared to ensure that the solutions are consistent with each other. The analytical solutions of the dimensionless velocity and temperature fields within the laminar boundary layer of the wedge flow are obtained. The approximation solutions of the dimensionless temperature of the wedge flow under subsonic speed and isothermal wall boundary conditions and the dimensionless temperature of the wedge flow under supersonic speed and adiabatic wall boundary conditions are provided. The velocity and temperature distributions of the airflow outside the strut are obtained through numerical simulation and the pattern of changes in the velocity and temperature within the laminar boundary layer of the strut is revealed. Numerical simulation on gas jet cooling and regenerative cooling for the strut are simulated and shown to be effective for thermal protection. Using a strut with rough internal surface and aviation kerosene as the cooling medium is effective at cooling. The experiment fixture used to simulate the outlet temperature of the combustor and the experimental fixture used to simulate the dynamic temperature of the compressor are designed and built. The dynamic temperature of the compressor airflow is measured using combined thermocouples. Experimental results show that the dynamic error caused by the thermal inertia of the thermocouple can be eliminated by the compensation algorithm.

scholarly journals Calculations of Velocity and Temperature in a Polar Glacier using the Finite-Element Method

1979 ◽  
Vol 24 (90) ◽  
pp. 131-146 ◽  
Author(s):  
Roger LeB. Hooke ◽  
Charles F. Raymond ◽  
Richard L. Hotchkiss ◽  
Robert J. Gustafson
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Temperature Distribution ◽  
Differential Equations ◽  
Boundary Conditions ◽  
Velocity Distribution ◽  
Vertical Velocity ◽  
Measured Temperature ◽  
Temperature Distributions ◽  
Flow Law

AbstractNumerical methods based on quadrilateral finite elements have been developed for calculating distributions of velocity and temperature in polar ice sheets in which horizontal gradients transverse to the flow direction are negligible. The calculation of the velocity field is based on a variational principle equivalent to the differential equations governing incompressible creeping flow. Glen’s flow law relating effective strain-rateε̇ and shear stressτbyε̇ = (τ/B)nis assumed, with the flow law parameterBvarying from element to element depending on temperature and structure. As boundary conditions, stress may be specified on part of the boundary, in practice usually the upper free surface, and velocity on the rest. For calculation of the steady-state temperature distribution we use Galerkin’s method to develop an integral condition from the differential equations. The calculation includes all contributions from vertical and horizontal conduction and advection and from internal heat generation. Imposed boundary conditions are the temperature distribution on the upper surface and the heat flux elsewhereFor certain simple geometries, the flow calculation has been tested against the analytical solution of Nye (1957), and the temperature calculation against analytical solutions of Robin (1955) and Budd (1969), with excellent results.The programs have been used to calculate velocity and temperature distributions in parts of the Barnes Ice Cap where extensive surface and bore-hole surveys provide information on actual values. The predicted velocities are in good agreement with measured velocities if the flow-law parameterBis assumed to decrease down-glacier from the divide to a point about 2 km above the equilibrium line, and then remain constant nearly to the margin. These variations are consistent with observed and inferred changes in fabric from fine ice with randomc-axis orientations to coarser ice with single- or multiple-maximum fabrics. In the wedge of fine-grained deformed superimposed ice at the margin,Bincreases again.Calculated and measured temperature distributions do not agree well if measured velocities and surface temperatures are used in the model. The measured temperature profiles apparently reflect a recent climatic warming which is not incorporated into the finite-element model. These profiles also appear to be adjusted to a vertical velocity distribution which is more consistent with that required for a steady-state profile than the present vertical velocity distribution.

scholarly journals Thermal conductivity of porous ice in hailstone shells

1996 ◽  
Vol 42 (141) ◽  
pp. 195-200
Author(s):  
Guoguang Zheng ◽  
Roland List
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Linear Dependence ◽  
Internal Heat ◽  
Density Range ◽  
Surface Temperature Distribution ◽  
Temperature Distributions ◽  
Evolving Surface

AbstractThe thermal conductivity and diffusivity of porous ice accreted on spherical and spheroidal hailstone models were measured over a density range of 620–915 kg m−3. By scanning the evolving surface temperature distributions during cooling in a cold airflow the thermal conductivity was varied in iterative fashion until the internal heat flux produced the correct surface temperature distribution. The results indicate a linear dependence of the thermal conductivity,ki, and diffusivity,αi, on density. For example, lowering the density by 10% lowerskiby 15%. Within the range of cloud conditions, the density variations affect the thermal parameters more than temperature does. The results also indicate a continuous decrease of the thermal conductivity from bulk ice via consolidated porous ice to loosely packed snow.

scholarly journals Temperature Measurement Technologies and Their Application in the Research of Fuel Cells

2003 ◽  
Author(s):  
Mao Hai Wang ◽  
Hang Guo ◽  
Chong Fang Ma ◽  
Fang Ye ◽  
Jian Yu ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Temperature Distribution ◽  
Thermal Imaging ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Temperature Fields ◽  
Infrared Thermal Imaging ◽  
Exterior Surface ◽  
Temperature Distributions ◽  
Exchange Membrane

Fuel cells have attracted extensive attention throughout the world in recent years for their high efficiency and high environmental compatibility. Temperature plays a key role in achieving high performance of fuel cells because it deeply influences the activity of catalyst, dehydration of solid polymer membrane, mass transfer and heat management of fuel cells. The temperature distribution has close relationship with current density distribution and lifetime of fuel cells because the uniformity of temperature distribution is a quite important problem for fuel cells. In this paper, a review of temperature measurement technologies that can be used to measure temperature distribution of fuel cells was presented. The measurement of cathode exterior surface temperature fields of a hydrogen proton exchange membrane fuel cell under various operational conditions was conducted by using the technology of infrared thermal imaging. The proton exchange membrane fuel cell structure was designed for uniformity of input heat. A NEC TH5102 thermo tracer was applied to measure the cathode exterior surface temperature distributions of the cell with 5cm2 active area. The experimental results showed that the infrared thermal imaging is an effective method to measure the exterior temperature fields of the PEMFC. The cathode temperature distributions of the cell varied with cell temperatures and flow rates.

scholarly journals Calculations of Velocity and Temperature in a Polar Glacier using the Finite-Element Method

1979 ◽  
Vol 24 (90) ◽  
pp. 131-146 ◽  
Author(s):  
Roger LeB. Hooke ◽  
Charles F. Raymond ◽  
Richard L. Hotchkiss ◽  
Robert J. Gustafson
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Temperature Distribution ◽  
Differential Equations ◽  
Boundary Conditions ◽  
Velocity Distribution ◽  
Vertical Velocity ◽  
Measured Temperature ◽  
Temperature Distributions ◽  
Flow Law

AbstractNumerical methods based on quadrilateral finite elements have been developed for calculating distributions of velocity and temperature in polar ice sheets in which horizontal gradients transverse to the flow direction are negligible. The calculation of the velocity field is based on a variational principle equivalent to the differential equations governing incompressible creeping flow. Glen’s flow law relating effective strain-rate ε̇ and shear stress τ by ε̇ = (τ/B)n is assumed, with the flow law parameter B varying from element to element depending on temperature and structure. As boundary conditions, stress may be specified on part of the boundary, in practice usually the upper free surface, and velocity on the rest. For calculation of the steady-state temperature distribution we use Galerkin’s method to develop an integral condition from the differential equations. The calculation includes all contributions from vertical and horizontal conduction and advection and from internal heat generation. Imposed boundary conditions are the temperature distribution on the upper surface and the heat flux elsewhereFor certain simple geometries, the flow calculation has been tested against the analytical solution of Nye (1957), and the temperature calculation against analytical solutions of Robin (1955) and Budd (1969), with excellent results.The programs have been used to calculate velocity and temperature distributions in parts of the Barnes Ice Cap where extensive surface and bore-hole surveys provide information on actual values. The predicted velocities are in good agreement with measured velocities if the flow-law parameter B is assumed to decrease down-glacier from the divide to a point about 2 km above the equilibrium line, and then remain constant nearly to the margin. These variations are consistent with observed and inferred changes in fabric from fine ice with random c-axis orientations to coarser ice with single- or multiple-maximum fabrics. In the wedge of fine-grained deformed superimposed ice at the margin, B increases again.Calculated and measured temperature distributions do not agree well if measured velocities and surface temperatures are used in the model. The measured temperature profiles apparently reflect a recent climatic warming which is not incorporated into the finite-element model. These profiles also appear to be adjusted to a vertical velocity distribution which is more consistent with that required for a steady-state profile than the present vertical velocity distribution.

Thermal conductivity of porous ice in hailstone shells

1996 ◽  
Vol 42 (141) ◽  
pp. 195-200
Author(s):  
Guoguang Zheng ◽  
Roland List
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Linear Dependence ◽  
Internal Heat ◽  
Density Range ◽  
Surface Temperature Distribution ◽  
Temperature Distributions ◽  
Evolving Surface

AbstractThe thermal conductivity and diffusivity of porous ice accreted on spherical and spheroidal hailstone models were measured over a density range of 620–915 kg m−3. By scanning the evolving surface temperature distributions during cooling in a cold airflow the thermal conductivity was varied in iterative fashion until the internal heat flux produced the correct surface temperature distribution. The results indicate a linear dependence of the thermal conductivity, ki, and diffusivity, αi, on density. For example, lowering the density by 10% lowers ki by 15%. Within the range of cloud conditions, the density variations affect the thermal parameters more than temperature does. The results also indicate a continuous decrease of the thermal conductivity from bulk ice via consolidated porous ice to loosely packed snow.

scholarly journals Development of a Simplified Regression Equation for Predicting Underground Temperature Distributions in Korea

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2894
Author(s):  
Sung-Woo Cho ◽  
Pyeongchan Ihm
Keyword(s):  
Temperature Distribution ◽  
Surface Temperature ◽  
Amplitude Ratio ◽  
Ground Surface ◽  
Regression Equation ◽  
Ground Temperature ◽  
Coefficient Of Determination ◽  
Outdoor Temperature ◽  
Geothermal Heat ◽  
Temperature Distributions

The Korea Meteorological Administration (KMA) measures outdoor temperature and ground surface temperature at 95 observation points, but monthly ground temperatures by depth, which are important for using geothermal heat, are only provided for nine points. Since the ground temperature is known in the vicinity of only nine observation points, it is very difficult to predict underground temperature in the field. This study develops a simplified regression equation for predicting underground temperature distributions, compares the prediction results with the experimental data of Korea’s representative areas and the data measured in this study, and examines the validity of the developed regression equation. The regression equation for predicting temperature amplitudes at ground depths of 1.0, 3.0, and 5.0 m was derived using the amplitude ratio of outdoor temperature and surface temperature provided by KMA at nine points in Korea from 2006 to 2015. The coefficient of determination was as high as 0.93 (95% confidence level). In addition, the field-measured ground temperature distribution at a depth of 3 m was in good agreement with the predicted ground temperature distribution in Changwon districts for the whole of 2017.

Holocene sea surface temperature variations recorded in corals from Kikai Island, Japan

2017 ◽  
Vol 51 (4) ◽  
pp. e9-e14 ◽  
Author(s):  
Hiroto Kajita ◽  
Atsuko Yamazaki ◽  
Takaaki Watanabe ◽  
Chung-Che Wu ◽  
Chuan-Chou Shen ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Sea Surface ◽  
Temperature Variations

scholarly journals 3D Thermal Monitoring of Jointed Rock Masses through Infrared Thermography and Photogrammetry

2021 ◽  
Vol 13 (5) ◽  
pp. 957
Author(s):  
Guglielmo Grechi ◽  
Matteo Fiorucci ◽  
Gian Marco Marmoni ◽  
Salvatore Martino
Keyword(s):  
Surface Temperature ◽  
Infrared Thermography ◽  
Point Cloud ◽  
Engineering Geology ◽  
Point Clouds ◽  
Jointed Rock ◽  
Geometric Accuracy ◽  
Rock Masses ◽  
Natural Systems ◽  
Temperature Distributions

The study of strain effects in thermally-forced rock masses has gathered growing interest from engineering geology researchers in the last decade. In this framework, digital photogrammetry and infrared thermography have become two of the most exploited remote surveying techniques in engineering geology applications because they can provide useful information concerning geomechanical and thermal conditions of these complex natural systems where the mechanical role of joints cannot be neglected. In this paper, a methodology is proposed for generating point clouds of rock masses prone to failure, combining the high geometric accuracy of RGB optical images and the thermal information derived by infrared thermography surveys. Multiple 3D thermal point clouds and a high-resolution RGB point cloud were separately generated and co-registered by acquiring thermograms at different times of the day and in different seasons using commercial software for Structure from Motion and point cloud analysis. Temperature attributes of thermal point clouds were merged with the reference high-resolution optical point cloud to obtain a composite 3D model storing accurate geometric information and multitemporal surface temperature distributions. The quality of merged point clouds was evaluated by comparing temperature distributions derived by 2D thermograms and 3D thermal models, with a view to estimating their accuracy in describing surface thermal fields. Moreover, a preliminary attempt was made to test the feasibility of this approach in investigating the thermal behavior of complex natural systems such as jointed rock masses by analyzing the spatial distribution and temporal evolution of surface temperature ranges under different climatic conditions. The obtained results show that despite the low resolution of the IR sensor, the geometric accuracy and the correspondence between 2D and 3D temperature measurements are high enough to consider 3D thermal point clouds suitable to describe surface temperature distributions and adequate for monitoring purposes of jointed rock mass.

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