APPLICATIONS OF RADIATION
Chairman: S.T. Surzhikov
NEAR INFRARED SPECTROSCOPY AND IMAGING
Matthew R. Jones
Department of Aerospace & Mechanical Engineering
The University of Arizona
Tucson, Arizona 85721 USA
Advances in the area of opto-electronics which allow the detection of low intensity light
have increased interest in the study of light propagation in turbid media. One of the most
exciting applications of these emerging technologies is the use of near infrared
spectroscopy and imaging in medicine. Since the absorption of photons by biological
tissues is low in the 700-900 nm spectral region, it is feasible to use near infrared radiation
as a medical probe. Few advancements have had a greater impact on medical science than
the development of techniques to non-invasively determine the internal structure of
biological tissues. Many view the development of near infrared spectroscopy and imaging
techniques as the next important step in the continued improvement of this vital area of
medical science. The use of near infrared radiation has two primary advantages over the use
of x-rays. The first advantage is that near infrared light is non-ionizing, so it is safer than
x-rays. The second advantage is that the near infrared absorption spectra of biological
tissue depends on the functional status of the tissue, so near infrared spectroscopy and
imaging can provide functional as well as structural information. However, unlike x-rays,
near infrared radiation is highly scattered by biological tissues. Therefore, image
reconstruction and spectroscopic techniques capable of extracting useful information from
multiply scattered light are necessary. This paper describes some techniques that are being
developed to measure the optical properties and to obtain images of biological tissues from
an analysis of multiply scattered radiation.
RADIATION AND THERMOPHORESIS INTERACTION IN LAMINAR FREE CONVECTION
Yaman Yener and Hanlin Weng
Northeastern University, Boston, MA 02115, U.S.A.
CEA-Saclay, 91191 Gif/Yvette Cedex, France
The interaction between radiation and thermophoresis in laminar free convection
along a vertical cold surface is investigated. The fluid is a radiatively nonparticipating
constant-property gas containing emitting, absorbing and isotropically scattering gray
aerosol particles. The radiative properties of the gas-aerosol mixture are considered to be
proportional to the local concentration of particles in the mixture. The vertical surface,
maintained isothermal at a temperature lower than the fluid bulk temperature, assumed to
be opaque, gray, and diffusely emitting and diffusely reflecting. Formal relations
developed by the use of the Galerkin method are presented for the solution of the radiation
part of the problem. An iterative numerical solution scheme is implemented by making use
of the Keller block elimination method to solve the momentum, energy and particle
concentration equations. Various results are presented in graphical forms to demonstrate
the effects of thermophoresis and radiation on the velocity, temperature and particle
RADIATIVE HEAT TRANSFER IN A LAYER OF ANISOTROPIC SCATTERING FOG SUBJECTED TO COLLIMATED IRRADIATION
Institute of Fluid Science, Tohoku University
Aoba-ku, Katahira 2-1-1, Sendai 980-77, Japan
The radiation element method by ray emission model, REM2, is applied to plane parallel and
anisotropic scattering participating media. The proposed method, REM2, is applicable to arbitrary
thermal conditions in radiation elements and at boundary surfaces. The boundary surfaces can be
specular and/or diffuse. Both collimated and diffuse incident irradiation can be adopted at a boundary
surface. The proposed method can be used to analyze a variety of thermal and boundary conditions,
simply by changing the parameters of the radiation elements.
The provisos method  requires that the participating medium is isotropic. In order to include
anisotropic scattering media, a delta function approximation is applied. Gas absorption due to
participating gases such as H2O and CO2 is taken into account by employing a statistical narrow-band
The proposed method is applied to a modeled fog consisting of water droplets, humid air layers and a
specular boundary surface subjected to an oblique collimated flux.
In the Pacific Ocean near the coast of Sendai in Japan, fog is observed on the sea surface during the
summer. This fog is formed because a cold current in the sea interacts with warm humid air, resulting the
formation of mist in the air. In order to simplify the model, mono-dispersed water droplets of diameter
suspended in the humid air are considered. The modeled fog is illustrated in Fig. 1. The
thickness of the fog layer is xl m and the number density of water droplets is np m-3.
A collimated solar flux of intensity qc,s is irradiated onto the fog layer at an incident angle of . The
specular reflectivity of the interface between the sea surface and the fog layer is approximated by the
normal reflectivity of water. The value can be determined using electromagnetic theory and the complex
refractive index of water .
The solar flux transmitted through the modeled fog becomes smaller as and xl X np increase. The
transmitted solar flux is calculated for both isotropic and anisotropic scattering phase functions. The flux
of isotropic scattering particles shows smaller value than that with an anisotropic phase function.
The direction of radiation flux for a long wavelength of infrared region is from water surface towards the
sky, and its intensity is about 5 to 10 % of transmitted solar flux. The radiation flux for a long
wavelength is affected by gas absorption. This is negligible for the case of large particle number density
and low partial pressure of water vapor. The radiation flux becomes smaller for the case of small particle
density and humid air.
The temperature close to the sea surface is higher than that of the upper fog layer. The temperature jump
at the interface between the sea and the fog layer is large for a optically thin fog.
- Maruyama, S. and Aihara, T., Radiation Heat Transfer of Arbitrary Three-Dimensional Absorbing, Emitting and Scattering Media and Specular and Diffuse Surfaces, ASME J. Heat Transfer, Vol. 119, pp. 129-136, (1997).
- Maruyama, S., Radiation Heat Transfer Between Arbitrary Three-Dimensional Bodies with Specular and Diffuse Surfaces, Numerical Heat Transfer, Part A, Vol. 24, pp. 181-196, (1993).
Fig. 2 Analysis model of the sea fog irradiated by solar radiation.
OPTICAL DIAGNOSTICS OF PARTICLES IN HIGH-TEMPERATURE FLOWS
Olga S.Vaulina, Anatoli P.Nefedov, Oleg F.Petrov, Alez l. Samarian
High Energy Density Research Center
Russian Academy of Sciences, IVTAN. Izhorskaya. 13/19.
Moscow, 127412, Russia
A combination of novel methods for determining the temperature,
mean size, concentration and spectral refractive index of
particles in high-temperature flows is presented. The technique is
based on empirical inverting the forward-scattering transmittance
and spectral emission-absorption measurements. The measurements
are successfully inverted for the SiO2, CeO2, and ash particles in
combustion flows. The particle temperature, concentration, mean
size, and complex refractive index are retrieved.