Publication Cover
Numerical Heat Transfer, Part A: Applications
An International Journal of Computation and Methodology
Volume 71, 2017 - Issue 5
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Original Articles

Thermal analysis of laser-irradiated tissue phantoms using a novel separation of the variables-based discrete transfer method

, &
Pages 575-589 | Received 02 Aug 2016, Accepted 28 Nov 2016, Published online: 23 Mar 2017
 

ABSTRACT

Thermal analysis of tissue phantoms subjected to short pulse laser irradiation has been presented. The transient radiative transfer equation (RTE) has been solved using a novel separation of variables-based discrete transfer method (DTM) recently developed by the present authors (Nirgudkar et al. [Citation21]). As an advancement, the solution of RTE has been coupled with Pennes’ bioheat transfer equation for determining the temperature distribution. Homogenous as well as phantoms embedded with optical inhomogeneity have been considered. The numerical model has been verified against the results available in the literature. This study clearly reveals the influence of the nature of the embedded inhomogeneity and its relative contrast on the resultant temperature distribution inside the body of the tissue phantom.

Nomenclature

a=

anisotropy factor

c=

velocity of light in medium

Cv=

specific heat

G=

incident intensity

I=

intensity

k=

thermal conductivity

M=

number of discrete directions

=

unit vector normal to the surface

p=

scattering phase function

q=

heat flux

s=

distance travelled by beam

=

unit vector in s direction

t=

time

T=

temperature

tp=

pulse width of laser

Greek symbols=
σs=

Stefan-Boltzmann's constant

β=

extinction coefficient

=

emissivity

θ, ϕ=

polar and azimuthal angle

κ=

absorption coefficient

μ, ζ=

Direction cosines in x and y direction

ρ=

density

σ=

scattering coefficient

τ=

optical thickness

Ω=

solid angle

ω=

scattering albedo

ωb=

blood perfusion rate

Subscripts=
0=

reference or incident value

av=

average

b=

blood/black body

c=

collimated

d=

diffused

w=

wall

Superscripts=
D=

downstream

m=

index for a discrete direction

U=

upstream

*=

non-dimensional parameter

Nomenclature

a=

anisotropy factor

c=

velocity of light in medium

Cv=

specific heat

G=

incident intensity

I=

intensity

k=

thermal conductivity

M=

number of discrete directions

=

unit vector normal to the surface

p=

scattering phase function

q=

heat flux

s=

distance travelled by beam

=

unit vector in s direction

t=

time

T=

temperature

tp=

pulse width of laser

Greek symbols=
σs=

Stefan-Boltzmann's constant

β=

extinction coefficient

=

emissivity

θ, ϕ=

polar and azimuthal angle

κ=

absorption coefficient

μ, ζ=

Direction cosines in x and y direction

ρ=

density

σ=

scattering coefficient

τ=

optical thickness

Ω=

solid angle

ω=

scattering albedo

ωb=

blood perfusion rate

Subscripts=
0=

reference or incident value

av=

average

b=

blood/black body

c=

collimated

d=

diffused

w=

wall

Superscripts=
D=

downstream

m=

index for a discrete direction

U=

upstream

*=

non-dimensional parameter

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