scholarly journals Thermal Relaxation in Titanium Nanowires: Signatures of Inelastic Electron-Boundary Scattering in Heat Transfer

2017 ◽  
Vol 189 (3-4) ◽  
pp. 204-216 ◽  
Author(s):  
Teemu Elo ◽  
Pasi Lähteenmäki ◽  
Dmitri Golubev ◽  
Alexander Savin ◽  
Konstantin Arutyunov ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Relaxation ◽  
Inelastic Electron ◽  
Boundary Scattering

Anisotropic heat transfer prediction of multiscale wires using pulse laser thermal relaxation technique

2013 ◽  
Vol 555 ◽  
pp. 239-246 ◽  
Author(s):  
Jin W. Tan ◽  
Yue Cheng ◽  
Denis S.G. Yap ◽  
Feng Gong ◽  
Son T. Nguyen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pulse Laser ◽  
Thermal Relaxation ◽  
Relaxation Technique

Modeling and Simulation on Heat Transfer in Blood Vessels Subject to a Transient Laser Irradiation

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Xuelan Zhang ◽  
Liancun Zheng ◽  
Lin Liu ◽  
Xinxin Zhang
Keyword(s):  
Heat Transfer ◽  
Blood Vessels ◽  
Laser Irradiation ◽  
Numerical Solutions ◽  
Thermal Relaxation ◽  
Initial Time ◽  
Laser Exposure ◽  
Conduction Model ◽  
Heaviside Step Function ◽  
The Impact

Abstract This paper investigates heat transfer of blood vessels subject to transient laser irradiation, where the irradiation is extremely short times and has high power. The modified Fourier heat conduction model (Cattaneo–Christov flux) and Heaviside step function are used in describing the thermal relaxation and temperature jump characteristics in initial time. A novel auxiliary function is introduced to avoid three-level discretization and temporal–spatial mixed derivative, and the numerical solutions are obtained by Crank–Nicolson alternating direction implicit (ADI) scheme. Results indicate that the temperature distributions in blood vessels strongly depend on the blood property, the laser exposure time, the blood flowrate (Reynolds number) and the thermal relaxation parameter. The isothermal curve exhibits asymmetric characteristics due to the impact of blood flow, and the higher blood velocity leads to more asymmetric isotherm and less uniform thermal distribution. Further, the heat-flux relaxation phenomenon is also captured, and its effect on blood temperature becomes more noticeable as blood flows downstream of blood vessels.

ANALYTICAL SOLUTIONS OF NON-FOURIER PENNES AND CHEN–HOLMES EQUATIONS

2012 ◽  
Vol 05 (04) ◽  
pp. 1250022 ◽  
Author(s):  
WEIPING ZHU ◽  
FANGBAO TIAN ◽  
PENG RAN
Keyword(s):  
Heat Transfer ◽  
Analytical Solutions ◽  
Laplace Transformation ◽  
Solution Method ◽  
Thermal Relaxation ◽  
Blood Perfusion ◽  
Good Alternative ◽  
Tissue Temperature ◽  
Particular Solution ◽  
Insight Into

The analytical solutions of non-Fourier Pennes and Chen–Holmes equations are obtained using the Laplace transformation and particular solution method in the present paper. As an application, the effects of the thermal relaxation time τ, the blood perfusion wb, and the blood flow velocity v on the biological skin and inner tissue temperature T are studied in detail. The results obtained in this study provide a good alternative method to study the bio-heat and a biophysical insight into the understanding of the heat transfer in the biotissue.

scholarly journals Assessment of Hyperbolic Heat Transfer Equation in Theoretical Modeling for Radiofrequency Heating Techniques

2008 ◽  
Vol 2 (1) ◽  
pp. 22-27 ◽  
Author(s):  
Juan A López-Molina ◽  
Maria J Rivera ◽  
Macarena Trujillo ◽  
Fernando Burdío ◽  
Juan L Lequerica ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Transfer Equation ◽  
Cardiac Tissue ◽  
Thermal Relaxation ◽  
Propagation Speed ◽  
Biological Tissues ◽  
Heating Time ◽  
Theoretical Modeling ◽  
Rf Heating ◽  
Heat Transfer Equation

Theoretical modeling is a technique widely used to study the electrical-thermal performance of different surgical procedures based on tissue heating by use of radiofrequency (RF) currents. Most models employ a parabolic heat transfer equation (PHTE) based on Fourier’s theory, which assumes an infinite propagation speed of thermal energy. We recently proposed a one-dimensional model in which the electrical-thermal coupled problem was analytically solved by using a hyperbolic heat transfer equation (HHTE), i.e. by considering a non zero thermal relaxation time. In this study, we particularized this solution to three typical examples of RF heating of biological tissues: heating of the cornea for refractive surgery, cardiac ablation for eliminating arrhythmias, and hepatic ablation for destroying tumors. A comparison was made of the PHTE and HHTE solutions. The differences between their temperature profiles were found to be higher for lower times and shorter distances from the electrode surface. Our results therefore suggest that HHTE should be considered for RF heating of the cornea (which requires very small electrodes and a heating time of 0.6 s), and for rapid ablations in cardiac tissue (less than 30 s).

Numerical simulation of non-Fourier effects in combined heat transfer

2010 ◽  
Vol 225 (2) ◽  
pp. 429-436
Author(s):  
E Izadpanah ◽  
S Talebi ◽  
M H Hekmat
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Heat Conduction Equation ◽  
Splitting Method ◽  
Thermal Relaxation ◽  
Conduction Equation ◽  
Hyperbolic Heat Conduction ◽  
Wave Nature ◽  
Fourier Heat Conduction ◽  
Combined Heat Transfer

The non-Fourier effects on transient and steady temperature distribution in combined heat transfer are studied. The processes of coupled conduction and radiation heat transfer in grey, absorbing, emitting, scattering, one-dimensional medium with black boundary surfaces are analysed numerically. The hyperbolic heat conduction equation is solved by flux splitting method, and the radiative transfer equation is solved by P1 approximate method. The transient thermal responses obtained from non-Fourier heat conduction equation are compared with those obtained from the Fourier heat conduction equation. The results show that the non-Fourier effect can be important when the conduction to radiation parameter and the thermal relaxation time are larger. Further, the radiation effect is more pronounced at small values of single scattering albedo and conduction to radiation parameters. Analysis results indicate that the internal radiation in the medium significantly influences the wave nature.

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