scholarly journals Extended Generalized Riccati Equation Mapping for Thermal Traveling-Wave Distribution in Biological Tissues through a Bio-Heat Transfer Model with Linear/Quadratic Temperature-Dependent Blood Perfusion

2013 ◽  
Vol 04 (10) ◽  
pp. 1471-1484 ◽  
Author(s):  
Emmanuel Kengne ◽  
Fathi Ben Hamouda ◽  
Ahmed Lakhssassi
Keyword(s):  
Heat Transfer ◽  
Traveling Wave ◽  
Blood Perfusion ◽  
Biological Tissues ◽  
Transfer Model ◽  
Linear Quadratic ◽  
Temperature Dependent ◽  
Generalized Riccati Equation ◽  
Wave Distribution ◽  
Quadratic Temperature

Nonclassical Heat Transfer Models for Laser-Induced Thermal Damage in Biological Tissues

2011 ◽  
Author(s):  
Jianhua Zhou ◽  
J. K. Chen ◽  
Yuwen Zhang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Conduction ◽  
Temperature Gradient ◽  
Thermal Wave ◽  
Thermal Damage ◽  
Blood Perfusion ◽  
Biological Tissues ◽  
Phase Lag ◽  
Fourier Heat Conduction

To ensure personal safety and improve treatment efficiency in laser medical applications, one of the most important issues is to understand and accurately assess laser-induced thermal damage to biological tissues. Biological tissues generally consist of nonhomogeneous inner structures, in which heat flux equilibrates to the imposed temperature gradient via a thermal relaxation mechanism which cannot be explained by the traditional parabolic heat conduction model based on Fourier’s law. In this article, two non-Fourier heat conduction models, hyperbolic thermal wave model and dual-phase-lag (DPL) model, are formulated to describe the heat transfer in living biological tissues with blood perfusion and metabolic heat generation. It is shown that the non-Fourier bioheat conduction models could predict significantly different temperature and thermal damage in tissues from the traditional parabolic model. It is also found that the DPL bioheat conduction equations can be reduced to the Fourier heat conduction equations only if both phase lag times of the temperature gradient (τT) and the heat flux (τq) are zero. Effects of laser parameters and blood perfusion on the thermal damage simulated in tissues are also studied. The result shows that the overall effects of the blood flow on the thermal response and damage are similar to those of the time delay τT. The two-dimensional numerical results indicate that for a local heating with the heated spot being smaller than the tissue bulk, the variations of the non-uniform distributions of temperature suggest that the multi-dimensional effects of thermal wave and diffusion not be negligible.

Bio-Heat Transfer in a Model Skin Subject to a Train of Short Pulse Irradiation

2008 ◽  
Author(s):  
Jian Jiao ◽  
Zhixiong Guo
Keyword(s):  
Heat Transfer ◽  
Temperature Rise ◽  
Ultrashort Pulse ◽  
Short Pulse ◽  
Temperature Response ◽  
Biological Tissues ◽  
Skin Tissue ◽  
Discrete Ordinates ◽  
Transfer Model ◽  
Pulse Irradiation

Thermal analysis of biological tissues subject to a train of ultrashort pulse irradiations was made of developing a combined time-dependent radiation and conduction bio-heat transfer model. A model skin tissue stratified as three layers with different optical, thermal and physiological properties was considered. Temperature response of the skin tissue exposed to a single ultrashort pulse irradiation was firstly analyzed by the finite volume method in combination with the transient discrete ordinates method. This temperature rise was found to reach pseudo steady state within an extremely short time period in which thermal diffusion is negligible. Since the tissue properties were assumed to be constant during a train of pulse irradiation, this temperature rise subject to a single pulse can be employed for repeated pulses. In the same time, Pennes’ equation was employed to study the bio-heat transfer in the meso-time scale. The effects of pulse strengths and repetition rate on the temperature response in the multi-layer skin tissue were investigated.

A variable property heat transfer model for predicting soil temperature profiles during simulated wildland fire conditions

2008 ◽  
Vol 17 (2) ◽  
pp. 205 ◽  
Author(s):  
Ebenezer K. Enninful ◽  
David A. Torvi
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Wildland Fire ◽  
Heat Fluxes ◽  
Transfer Model ◽  
Temperature Dependent ◽  
Heat Penetration ◽  
Experimental Values ◽  
Temperature Dependent Properties ◽  
Plant Shoots

A numerical model of heat transfer in dry soil was developed to predict temperatures and depth of lethal heat penetration during cone calorimeter tests used to simulate wildland fire exposures. The model was used to compare predictions made using constant and temperature-dependent thermal properties with experimental results for samples of dry sand exposed to heat fluxes of 25, 50 and 75 kW m–2. Depths of lethal heat penetration predicted using temperature-dependent properties were within 2 to 10% of the values determined using measured temperatures, while predictions made using constant properties were within 10 to 21% of the experimental values. In both cases, predictions made by the model were within the 1-cm accuracy with which the depth of seeds and plant shoots in the soil can be determined in practice. The model generally over-predicted the depth of lethal heat penetration in dry or moist soil when temperature-dependent properties were used, and over-predicted the depth of lethal heat penetration in soils with a moisture content of greater than 10% if constant thermal properties were used.

METHOD OF FUNDAMENTAL SOLUTIONS FOR NONLINEAR SKIN BIOHEAT MODEL

2014 ◽  
Vol 14 (04) ◽  
pp. 1450060 ◽  
Author(s):  
ZE-WEI ZHANG ◽  
HUI WANG ◽  
QING-HUA QIN
Keyword(s):  
Steady State ◽  
Governing Equation ◽  
Blood Perfusion ◽  
Bioheat Transfer ◽  
Method Of Fundamental Solutions ◽  
Linear Quadratic ◽  
Temperature Dependent ◽  
Perfusion Rate ◽  
Blood Perfusion Rate ◽  
Transfer Problems

In this paper, the method of fundamental solution (MFS) coupling with the dual reciprocity method (DRM) is developed to solve nonlinear steady state bioheat transfer problems. A two-dimensional nonlinear skin model with temperature-dependent blood perfusion rate is studied. Firstly, the original bioheat transfer governing equation with nonlinear term induced by temperature-dependent blood perfusion rate is linearized with the Taylor's expansion technique. Then, the linearized governing equation with specified boundary conditions is solved using a meshless approach, in which the DRM and the MFS are employed to obtain particular and homogeneous solutions, respectively. Several numerical examples involving linear, quadratic and exponential relations between temperature and blood perfusion rate are tested to verify the efficiency and accuracy of the proposed meshless model in solving nonlinear steady state bioheat transfer problems, and also the sensitivity of coefficients in the expression of temperature-dependent blood perfusion rate is analyzed for investigating the influence of blood perfusion rate to temperature distribution in skin tissues.

Bio-Heat Transfer Model of Human Eye Subjected to Retinal Laser Irradiation

2010 ◽  
Author(s):  
Arunn Narasimhan ◽  
Kaushal Kumar Jha
Keyword(s):  
Heat Transfer ◽  
Laser Radiation ◽  
Numerical Model ◽  
Laser Irradiation ◽  
Laser Power ◽  
Blood Perfusion ◽  
Transient Temperature ◽  
Transfer Model ◽  
Two Dimensional ◽  
Human Eye

Retinopathy is a surgical process in which maladies of the human eye are treated by laser irradiation. A two-dimensional numerical model of the human eye geometry has been developed to investigate steady and transient thermal effects due to laser radiation. In particular, the influence of choroidal pigmentations and choroidal blood convection — parameterized as a function of choroidal blood perfusion are investigated in detail. The Pennes bio-heat transfer equation is invoked as the governing equation and a finite volume formulation is employed in the numerical method. The numerical model is validated with available experimental and two-dimensional numerical results. For a 500 μm diameter spot size, laser power of 0.2 W, with 100% absorption of laser radiation in the Retinal Pigmented Epithelium (RPE) region, the peak RPE temperature is observed to be 175 °C at steady state, with no blood perfusion in choroid. It reduces to 168.5 °C when the choroidal blood perfusion rate is increased to 23.3 kgm−3s−1. However, under transient simulations, the peak RPE temperature is observed to remain constant at 104 °C after 100 ms of the laser surgery period. A truncated three-dimensional model incorporating multiple laser irradiation spots is also developed to observe the spatial effect of choroidal blood perfusion. For a circular array of seven uniformly distributed spots of identical diameter and laser power of 0.2 W, steady and transient temperature evolution are presented with analysis.

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