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.

Heat Transfer and Pressure Drop Correlation for Helicoidal Pipes of Rectangular Cross Section

2009 ◽  
Author(s):  
Christopher Katinas ◽  
Ahmad Fakheri
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Aspect Ratio ◽  
Friction Factor ◽  
Cross Section ◽  
Numerical Solutions ◽  
Rectangular Cross Section ◽  
Dean Number ◽  
Curvature Effects ◽  
The Impact

In this study, flow and heat transfer for laminar flow in curved channels of rectangular cross section is examined. The focus of the numerical solutions is on rectangular cross sections with an aspect ratio less than one, since little information is available for heat transfer in curved rectangular pipes whose width is greater than height. The study examines the impact of the aspect ratio and Dean number on both friction factor and Nusselt number. The results show that although both friction factor and Nusselt number increase as a result of curvature effects, the heat transfer enhancements significantly outweigh the friction factor penalty. Numerical solutions in this study consider the more realistic case of hydrodynamically developed and thermally developing flow.

scholarly journals Heat Transfer in a Porous Radial Fin: Analysis of Numerically Obtained Solutions

2017 ◽  
Vol 2017 ◽  
pp. 1-20 ◽  
Author(s):  
R. Jooma ◽  
C. Harley
Keyword(s):  
Heat Transfer ◽  
Systems Analysis ◽  
Numerical Solutions ◽  
Nonlinear Partial Differential Equation ◽  
Transformation Method ◽  
Dynamical Systems Analysis ◽  
Equation Modelling ◽  
The Stability ◽  
The Impact ◽  
State Case

A time dependent nonlinear partial differential equation modelling heat transfer in a porous radial fin is considered. The Differential Transformation Method is employed in order to account for the steady state case. These solutions are then used as a means of assessing the validity of the numerical solutions obtained via the Crank-Nicolson finite difference method. In order to engage in the stability of this scheme we conduct a stability and dynamical systems analysis. These provide us with an assessment of the impact of the nonlinear sink terms on the stability of the numerical scheme employed and on the dynamics of the solutions.

scholarly journals Finite Element Analysis of Variable Viscosity Impact on MHD Flow and Heat Transfer of Nanofluid Using the Cattaneo–Christov Model

Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 395 ◽  
Author(s):  
Liaqat Ali ◽  
Xiaomin Liu ◽  
Bagh Ali
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Finite Element ◽  
Differential Equations ◽  
Thermal Relaxation ◽  
Fluid Temperature ◽  
Flow And Heat Transfer ◽  
Flux Model ◽  
The Impact ◽  
Heat Flux Model

In this mathematical study, magnetohydrodynamic, time-independent nanofluid flow over a stretching sheet by using the Cattaneo–Christov heat flux model is inspected. The impact of the thermal, solutal boundary and gravitational body forces with the effect of double stratification on the mass flow and heat transfer phenomena is also observed. The temperature-dependent viscosity impact on heat transfer through a moving sheet with capricious heat generation in nanofluids have studied, and the viscosity of the fluid is presumed to deviate as the inverse function of temperature. With the appropriate transformations, the system of partial differential equations is transformed into a system of nonlinear ordinary differential equations. By applying the variational finite element method, the transformed system of equations is solved. The properties of the several parameters for buoyancy, velocity, temperature, stratification, and Brownian motion parameters have examined. The enhancement in the concentration and thermal boundary layer thickness of the nanofluid sheet due to the increment in the viscosity parameter, also increased the temperature and concentration of nanoparticles. Moreover, the fluid temperature declined with the increasing values of thermal relaxation parameter. This displays that the Cattaneo–Christov heat flux model provides a better assessment of temperature distribution. Moreover, confirmation of the code and precision of the numerical method has inveterate with the valuation of the presented results with previous studies.

Rotating flow of Oldroyd-B fluid over stretchable surface with Cattaneo – Christov heat flux

2017 ◽  
Vol 27 (10) ◽  
pp. 2207-2222 ◽  
Author(s):  
M. Mustafa ◽  
T. Hayat ◽  
A. Alsaedi
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Relaxation Time ◽  
Three Dimensional ◽  
Thermal Relaxation ◽  
Thermal Relaxation Time ◽  
Rotating Flow ◽  
Fluid Temperature ◽  
Conduction Model ◽  
Content Type

Purpose The purpose of this paper is to analyze the heat transfer effects on the stretched flow of Oldroyd-B fluid in a rotating frame. Cattaneo–Christov heat conduction model is considered, which accounts for the influence of thermal relaxation time. Design/methodology/approach Based on scale analysis, the usual boundary layer approximations are used to simplify the governing equations. The equations so formed have been reduced to self-similar forms by similarity transformations. A powerful analytic approach, namely, homotopy analysis method (HAM), has been applied to present uniformly convergent solutions for velocity and temperature profiles. Findings Suitable values of the so-called auxiliary parameter in HAM are obtained by plotting h-curves. The results show that boundary layer thickness has an inverse relation with fluid relaxation time. The rotation parameter gives resistance to the momentum transport and enhances fluid temperature. Thermal boundary layer becomes thinner when larger values of thermal relaxation time are chosen. Originality/value To the authors’ knowledge, this is the first attempt to study the three-dimensional rotating flow and heat transfer of Oldroyd-B fluid.

Melting and dynamic pressure: coupling of reactions, heat transfer and deformation

2021 ◽  
Author(s):  
Stefan Markus Schmalholz ◽  
Evangelos Moulas ◽  
Yuri Podladchikov
Keyword(s):  
Heat Transfer ◽  
Latent Heat ◽  
Numerical Solutions ◽  
Dynamic Pressure ◽  
Rock Deformation ◽  
Plate Boundaries ◽  
Melting Heat ◽  
Melt Migration ◽  
Melting Heat Transfer ◽  
The Impact

<p>Melting is a major process of plate tectonics, affecting divergent and convergent plate boundaries. Melting of rock is also a typical example of a coupled geological process, in which the associated transformation affects the heat transfer via the latent heat of fusion and the rock deformation via the volume change. However, petrological studies on melting usually focus on chemical aspects, such as differentiation of involved components, thermal studies usually focus only on the impact of latent heat on heat transfer, such as done in the classical Stefan problem of solidification. Similarly, studies focusing on lithosphere and mantle deformation usually only consider the impact on the effective viscosity, such as weakening due to partial melting, or the impact on buoyancy due to density changes. Many studies do, therefore, not consider coupling of melting, heat transfer and rock deformation. Indeed, a common assumption is that rock pressure, or mean stress, remains lithostatic during melting. While this assumption is attractive due to its simplicity, it is against the common knowledge derived from physical experiments and the well-established mechanical theories. Furthermore, theoretical models of melt migration would not work if pressure is everywhere lithostatic, or hydrostatic, because melt migration is driven by local deviations from the static stress state.</p><p>Here, we present simple mathematical models based on the fundamental laws of physics and thermodynamics (e.g. conservation of mass, momentum and energy) to study the fundamental coupling of melting, heat transfer and rock deformation, and to quantify dynamic pressure variations due to melting. We show both analytical and numerical solutions for these models. We discuss applications of these solutions to experiments and geological observations and estimate magnitudes of dynamic pressure resulting from melting under natural conditions.</p>

Inward Melting in a Vertical Tube Which Allows Free Expansion of the Phase-Change Medium

1982 ◽  
Vol 104 (2) ◽  
pp. 309-315 ◽  
Author(s):  
E. M. Sparrow ◽  
J. A. Broadbent
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Numerical Solutions ◽  
Melting Process ◽  
Vertical Tube ◽  
Conduction Model ◽  
Free Expansion ◽  
Melting Front ◽  
Quantitative Results ◽  
Change Temperature

Experiments on the melting of a phase-change medium in a vertical tube yielded quantitative results both for the heat transfer and the timewise evolution of the melting front. The upper surface of the phase-change medium was bounded by an insulated air space, which accommodated the volume changes which accompany the melting process. Numerical solutions based on a pure conduction model were also performed for comparison purposes. It was found that the rate of melting and the heat transfer are significantly affected by fluid motions in the liquid melt induced by the volume change and by natural convection, with the former being significant only at early times. For melting initiated with the solid at the phase-change temperature, the experimentally determined values of the energy transfer associated with the melting process were about 50 percent higher than those predicted by the conduction model. Furthermore, the measured values of the energy stored in the liquid melt were about twice the conduction prediction. A compact dimensionless correlation of the experimental results was achieved using the Fourier, Stefan, and Grashof numbers. Initial subcooling of the solid substantially decreased the rate of melting, with corresponding decreases in the energy transfers for melting and sensible heat storage.

scholarly journals Analytical and Numerical Investigation of Fe3O4–Water Nanofluid Flow over a Moveable Plane in a Parallel Stream with High Suction

Energies ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 198 ◽  
Author(s):  
A. J. Chamkha ◽  
A. M. Rashad ◽  
E. R. EL-Zahar ◽  
Hamed A. EL-Mky
Keyword(s):  
Heat Transfer ◽  
Numerical Solutions ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Partial Slip ◽  
Physical Parameters ◽  
Newtonian Heating ◽  
Ode System ◽  
The Impact ◽  
High Suction

In the current framework, a model is constituted to explore the impacts of high suction and partial slip on Fe3O4–water nanoliquid flow over a porous moveable surface in a parallel free stream. The mechanisms of heat transfer are also modeled in the existence of Newtonian heating effect. The obtaining PDEs are transformed into a non-linear ODE system employing appropriate boundary conditions to diverse physical parameters. The governing ODE system is solved using a singular perturbation technique that results in an analytical asymptotic solution as a function of the physical parameters. The obtained solution allows us to carry out an analytical parametric study to investigate the impact of the physical parameters on the nonlinear attitude of the system. The precision of the proposed method is verified by comparisons between the numerical and analytical results. The results confirm that the proposed technique yields a good approximation to the solution as well as the solution calculation has no CPU time-consuming or round off error. Numerical solutions are computed and clarified in graphs for the model embedded parameters. Moreover, profiles of the skin friction coefficient and the heat transfer rate are also portrayed and deliberated. The data manifests that both solid volume fraction and slip impact significantly alter the flow profiles. Moreover, an upward trend in temperature is anticipated for enhancing Newtonian heating strength. Additionally, it was found that both the nanofluid velocity and temperature distributions are decelerated when the solid volume fraction and suction parameters increase. Furthermore, a rise in slip parameter causes an increment in velocity profiles, and a rise in Biot number causes an increment in the temperature profiles.

Analysis of Heat and Moisture Transfer Beneath Freezer Foundations—Part I

2004 ◽  
Vol 126 (2) ◽  
pp. 716-725 ◽  
Author(s):  
Pirawas Chuangchid ◽  
Pyeonchan Ihm ◽  
Moncef Krarti
Keyword(s):  
Heat Transfer ◽  
Moisture Transfer ◽  
Experimental Tests ◽  
Frozen Soil ◽  
Heat And Moisture Transfer ◽  
Conduction Model ◽  
Coupled Heat Transfer ◽  
Time Required ◽  
Heat And Moisture ◽  
The Impact

This paper provides a numerical solution for simultaneous heat and moisture transfer within frozen soil beneath slab foundations of refrigerated warehouses. The developed solution is validated using data from experimental tests. A parametric analysis is then performed to determine the impact of slab insulation levels and to estimate the time required to reach steady-state ground-coupled heat transfer conditions. Finally, the solution is utilized to determine an effective soil thermal conductivity that could be used in a purely heat conduction model for ground-coupled heat transfer beneath freezers.

Chronic Laser Exposure Effects on Rabbit Retina

1972 ◽  
Vol 30 ◽  
pp. 54-55
Author(s):  
Burton B. Silver ◽  
Theodore Lawwill
Keyword(s):  
Laser Irradiation ◽  
Laser Light ◽  
Broad Band ◽  
Argon Laser ◽  
Atropine Sulfate ◽  
Ultrastructural Changes ◽  
Laser Exposure ◽  
Rabbit Retina ◽  
Histological Changes ◽  
Threshold Doses

Dutch-belted 1 to 2.5 kg anesthetized rabbits were exposed to either xenon or argon laser light administered in a broad band, designed to cover large areas of the retina. For laser exposure, the pupil was dilated with atropine sulfate 1% and pheny lephrine 10%. All of the laser generated power was within a band centered at 5145.0 Anstroms. Established threshold for 4 hour exposures to laser irradiation are in the order of 25-35 microwatts/cm2. Animals examined for ultrastructural changes received 4 hour threshold doses. These animals exhibited ERG, opthalmascopic, and histological changes consistent with threshold damage.One month following exposure the rabbits were killed with pentobarbitol. The eyes were immediately enucleated and dissected while bathed in 3% phosphate buffered gluteraldehyde.

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