Absorption/Scattering Coefficients and Scattering Phase Functions in Reticulated Porous Ceramics

1996 ◽  
Vol 118 (1) ◽  
pp. 79-87 ◽  
Author(s):  
T. J. Hendricks ◽  
J. R. Howell
Keyword(s):  
Wavelength Range ◽  
Phase Function ◽  
Theoretical Models ◽  
Porous Ceramics ◽  
Physical Structure ◽  
Radiative Properties ◽  
Discrete Ordinates ◽  
Scattering Coefficients ◽  
Scattering Phase ◽  
Phase Functions

Spectral absorption and scattering coefficients and spectral scattering phase functions have been derived for partially stabilized zirconia (PS ZrO2) and oxide-bonded silicon carbide (OB SiC) reticulated porous ceramics (RPCs) across the wavelength range 0.4–5.0 μm. These spectral radiative properties were investigated and quantified for 10 ppi (pores/inch), 20 ppi, and 65 ppi materials. Radiative properties were recovered from spectral hemispherical reflectance and transmittance measurements using inverse analysis techniques based upon discrete ordinates radiative models. Two dual-parameter phase functions were investigated for these materials: one based on the physical structure of reticulated porous ceramics and the other a modified Henyey–Greenstein phase function. The modified Henyey–Greenstein phase function provided the most consistent spectral radiative properties. PS ZrO2 radiative properties exhibited strongly spectrally dependent behavior across the wavelength range studied. OB SiC radiative properties exhibited radiative behavior that was relatively independent of wavelength across the wavelength spectrum studied. OB SiC also demonstrated consistently higher absorption coefficients than PS ZrO2 at all wavelengths. Spectral scattering albedos of PS ZrO2 were discovered to be in the range 0.81–0.999 and increased as ppi rating increased, while those for OB Sic were lower in the range 0.55–0.888 and decreased as ppi rating increased. The average extinction efficiencies for 0.4–5.0 μm were discovered to be 1.45 for Ps ZrO2 and 1.70 for OB SiC. Extinction coefficients were discovered to correlate well with geometric optics theoretical models and electromagnetic wave/fiber interaction models based on independent scattering and absorption mechanisms.

Effect of Configuration on the Radiative Properties of High Density Fiber Composites

2009 ◽  
Author(s):  
Siu-Chun Lee
Keyword(s):  
Phase Function ◽  
Fiber Composites ◽  
High Density ◽  
Radiative Properties ◽  
Numerical Analyses ◽  
Fiber Bundles ◽  
Scattering Coefficients ◽  
Polar Orientation ◽  
Scattering Phase ◽  
Scattering Phase Function

The influence of the geometric arrangement of fiber bundles on the radiative properties of high density woven fiber composites are examined in this paper. Of particular interest is the effect of the polar orientation of fiber bundles on the angular variation of the extinction and scattering coefficients and scattering phase function. The configuration effect is examined by numerical analyses on four types of cross-ply composites with fiber bundles at specific polar inclinations. The numerical analyses utilized the theoretical model that accounts for dependent scattering within, and uncorrelated scattering between, the dense fiber bundles. The extinction and scattering coefficients and scattering phase function are shown to depend strongly on the spatial orientation of the fiber bundles. These results indicate the feasibility of customizing the radiative properties and thus radiative transport by tailoring the geometric configuration of the fiber bundles.

scholarly journals Tomographic Characterization of a Semitransparent-Particle Packed Bed and Determination of its Thermal Radiative Properties

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
S. Haussener ◽  
W. Lipiński ◽  
J. Petrasch ◽  
P. Wyss ◽  
A. Steinfeld
Keyword(s):  
Packed Bed ◽  
Distribution Functions ◽  
Radiative Properties ◽  
Two Phase ◽  
Scattering Coefficients ◽  
Thermal Radiative Properties ◽  
High Temperature Processes ◽  
Phase Medium ◽  
Scattering Phase ◽  
Phase Functions

A two-phase medium consisting of densely packed large nonspherical semitransparent particles in a transparent fluid is considered. Its 3D digital geometry is obtained by computer tomography and employed to numerically calculate its porosity, specific surface, pore and particle size distributions, and the representative elementary volume for continuum domain. The collision-based Monte Carlo method is applied to calculate the probability distribution functions for attenuation path length and direction of incidence at the fluid-solid interface for each phase, which, in turn, are used to derive the extinction and scattering coefficients and the scattering phase functions. The methodology is applied to a packed bed of CaCO3 particles, used in industrially relevant high-temperature processes. Spectral and directional dependencies of the radiative properties are analyzed.

scholarly journals A Method for Deriving the Mean Volume Scattering Phase Function for Zodiacal Dust

1985 ◽  
Vol 85 ◽  
pp. 215-218
Author(s):  
S.S. Hong
Keyword(s):  
Linear Combination ◽  
Phase Function ◽  
Dust Particles ◽  
Zodiacal Light ◽  
Volume Scattering ◽  
Zodiacal Dust ◽  
Scattering Phase ◽  
The Mean ◽  
Scattering Phase Function ◽  
Phase Functions

AbstractA linear combination of 3 Henyey-Greenstein phase functions is substituted for the mean volume scattering phase function in the zodiacal light brightness integral. Results of the integral are then compared with the observed brightness to form residuals. Minimization of the residuals provides us with the best combination of Henyey-Greenstein functions for the scattering phase function of zodiacal dust particles.

scholarly journals Spectral Radiative Properties of a Liquid n-Octane Droplet in the Midinfrared Region

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Liang Zhao ◽  
Chaoyu Jing ◽  
Yu Jin ◽  
Jiangping Chen ◽  
Ke Yin ◽  
...  
Keyword(s):  
Refractive Index ◽  
Wavelength Range ◽  
Optical Constants ◽  
Absorption Efficiency ◽  
Efficiency Factor ◽  
Radiative Properties ◽  
Droplet Radius ◽  
Scattering Efficiency ◽  
Scattering Coefficients ◽  
Increasing Temperature

The optical constants of a liquid hydrocarbon such as liquid n-octane are basic material properties that may be used to evaluate their thermal radiation transfer capabilities. In this study, the ellipsometry method was used to measure the optical constants of liquid n-octane in the midinfrared wavelength range of 2.0–16.0 μm at temperatures of 20, 50, and 80°C. Experimental analyses indicate the significant effect of temperature on the refractive index, although it has little effect on the absorption index. With increasing temperature, the refractive index shows a linear decrease, and reduced density leads to weaker absorption intensities. The radiative properties of n-octane droplets, including the absorption and scattering efficiency factors of single droplets with droplet radii r = 10, 20, 50, and 100 μm and the absorption and scattering coefficients in a droplets-air system of droplet volume fractions fv = 2%, 3%, and 4%, were calculated using Mie theory. The numerical results indicate that, with increasing temperature, the absorption efficiency factor slightly decreases, and the variation trend of the scattering efficiency factor is more complicated. With increasing droplet radius, the absorption efficiency factor increases within the studied wavelength range, except for certain absorption peaks, but the scattering efficiency factor tends to decrease. While the absorption is greater, the scattering is weaker for a given droplet radius. With an increasing volume fraction of n-octane droplets, the absorption and scattering coefficients increase linearly within the studied wavelength range.

scholarly journals On the relationship between the scattering phase function of cirrus and the atmospheric state

2014 ◽  
Vol 14 (10) ◽  
pp. 14109-14157 ◽  
Author(s):  
A. J. Baran ◽  
K. Furtado ◽  
L.-C. Labonnote ◽  
S. Havemann ◽  
J.-C. Thelen ◽  
...  
Keyword(s):  
Model Prediction ◽  
Phase Function ◽  
Weather Prediction ◽  
Ice Crystals ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Nwp Model ◽  
Phase Functions ◽  
The Relationship ◽  
Good Agreement

Abstract. This is the first paper to investigate the relationship between the scattering phase function of cirrus and the relative humidity with respect to ice (RHi), using space-based solar radiometric angle-dependent measurements. The relationship between RHi, and the complexity of ice crystals has been previously studied using data from aircraft field campaigns and laboratory cloud chambers. However, to the best of our knowledge, there have been no studies to date that explore this relationship, through the use of remotely sensed space-based angle-dependent solar radiometric measurements. In this paper, a case study of semi-transparent cirrus is used to explore the possibility of such a relationship. Moreover, for the first time, RHi fields predicted by a high-resolution numerical weather prediction (NWP) model are combined with satellite retrievals of ice crystal complexity. The NWP model was initialised at midnight, on the 25 January 2010, and the mid-latitude RHi field was extracted from the NWP model at 13:00 UTC. At about the same time, there was a Polarization and Anisotropy of Reflectance for Atmospheric science coupled with Observations from a Lidar (PARASOL) overpass, and the PARASOL swath covered the NWP model predicted RHi field. The cirrus case was located over Scotland, and over the North Sea. From the satellite channel based at 0.865 μm, the directionally averaged and directional spherical albedos were retrieved between the scattering angles of about 80° and 130°. An ensemble model of cirrus ice crystals is used to predict phase functions that vary between phase functions that exhibit optical features (called pristine), to featureless phase functions. For each of the PARASOL pixels, the phase function that best minimised differences between the spherical albedos was selected. This paper reports a positive correlation between the scattering phase function and RHi. That is, the pristine and completely featureless phase functions are found to be correlated with RHi < 100%, and RHi> 100%, respectively. Moreover, it is demonstrated that the NWP model prediction of the vertical profile of RHi is in good agreement with independent aircraft-based physical retrievals of RHi. Furthermore, the NWP model prediction of the cirrus cloud-top height and its vertical extent is also found to be in good agreement with aircraft-based lidar measurements.

scholarly journals On the interpretation of an unusual in-situ measured ice crystal scattering phase function

2012 ◽  
Vol 12 (19) ◽  
pp. 9355-9364 ◽  
Author(s):  
A. J. Baran ◽  
J.-F. Gayet ◽  
V. Shcherbakov
Keyword(s):  
Phase Function ◽  
Asymmetry Parameter ◽  
Ice Crystals ◽  
Climate Modelling ◽  
Ice Crystal ◽  
Ice Particles ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Phase Functions

Abstract. In-situ Polar Nephelometer (PN) measurements of unusual ice crystal scattering phase functions, obtained near the cloud-top of a mid-latitude anvil cloud, at a temperature of about −58 °C, were recently reported by Gayet et al. (2012). The ice crystal habits that produced the phase functions consisted of aggregates of ice crystals and aggregates of quasi-spherical ice particles. The diameters of the individual quasi-spherical ice particles were estimated to be between about 15 μm and 20 μm. The measured-averaged scattering phase functions were featureless, at scattering angles less than about 100°, but an ice bow-like feature was noted between the scattering angles of about 120° to 160°. The estimated asymmetry parameter was 0.78 ± 0.04. In this paper, the averaged scattering phase function is interpreted in terms of a weighted habit mixture model. The model that provides the best overall fit to the measured scattering phase function comprises of highly distorted ten-element hexagonal ice aggregates and quasi-spherical ice particles. The smaller quasi-spherical ice crystals are represented by Chebyshev ice particles of order 3, and were assumed to have equivalent spherical diameters of 24 μm. The asymmetry parameter of the best overall model was found to be 0.79. It is argued that the Chebyshev-like ice particles are responsible for the ice bow-like feature and mostly dominate the scattered intensity measured by the PN. The results from this paper have important implications for climate modelling (energy balance of anvils), cloud physics and the remote sensing of cirrus properties.

Numerical Study on the Influence of Radiative Properties in Porous Media Combustion

2001 ◽  
Vol 123 (5) ◽  
pp. 951-957 ◽  
Author(s):  
Isabel Malico ◽  
Jose´ Carlos F. Pereira
Keyword(s):  
Porous Media ◽  
Numerical Study ◽  
Species Conservation ◽  
Radiative Properties ◽  
Isotropic Scattering ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Experimental Values ◽  
Phase Functions ◽  
Porous Media Combustion

The importance of radiation and of radiative properties (extinction coefficient, scattering albedo and scattering phase function) in inert porous media combustion was numerically assessed. The two-dimensional mass, momentum, solid and gas energy, and species conservation equations were solved. Emission, absorption and scattering by the porous media were taken into consideration and the S6 approximation was used to solve the radiative transfer equation. The temperature profiles are very sensitive to a perturbation in the radiative coefficients, particularly when the scattering albedo is increased. When compared to the isotropic scattering assumption, using zero, large diffuse spheres’, linear-anisotropic and modified Henyey–Greenstein phase functions leads to an average temperature difference no bigger than 7 percent. When radiation is neglected, the predicted temperature profile is not in agreement with the available experimental values.

scholarly journals On the interpretation of an unusual in-situ measured ice crystal scattering phase function

2012 ◽  
Vol 12 (5) ◽  
pp. 12485-12502 ◽  
Author(s):  
A. J. Baran ◽  
J.-F. Gayet ◽  
V. Shcherbakov
Keyword(s):  
Phase Function ◽  
Asymmetry Parameter ◽  
Ice Crystals ◽  
Climate Modelling ◽  
Ice Crystal ◽  
Ice Particles ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Phase Functions

Abstract. In-situ Polar Nephelometer (PN) measurements of unusual ice crystal scattering phase functions were recently reported by Gayet et al. (2012). The ice crystal habits that produced the phase functions were small chain-like aggregates, which had on their surfaces, smaller quasi-spherical ice crystals. The measured-averaged phase functions were featureless, at scattering angles less than about 100°, but an ice bow-like feature was noted between the scattering angles of about 120° to 160°. The estimated asymmetry parameter was 0.78 ± 0.04. In this paper, the phase function is interpreted in terms of a weighted habit mixture model. The best-fit model comprises of highly distorted ten element hexagonal ice aggregates, and the smaller quasi-spherical ice crystals are represented by Chebyshev ice particles. The weighted mean asymmetry parameter was found to be 0.81. It is argued that the Chebyshev-like ice particles are responsible for the ice bow-like feature and mostly dominate the scattered intensity measured by the PN. The results of this paper have important implications for climate modelling (energy balance of anvils) and the remote sensing of cirrus properties.

Spatially Resolved Lateral Transmission Measurements to Characterize Changes in the Scattering Coefficient and the Anisotropy Factor

2018 ◽  
Vol 72 (5) ◽  
pp. 757-764
Author(s):  
Sabrina Stocker ◽  
Florian Foschum ◽  
Alwin Kienle
Keyword(s):  
Phase Function ◽  
Light Propagation ◽  
Scattered Light ◽  
Scattering Coefficient ◽  
Polystyrene Microsphere ◽  
Reflectance Measurement ◽  
Scattering Coefficients ◽  
Spatially Resolved ◽  
Scattering Phase ◽  
Scattering Phase Function

A new setup is described to characterize the scattering coefficient and the scattering phase function of liquid media. The setup utilizes the basic idea of a spatially resolved reflectance measurement combined with a sophisticated illumination geometry. The sample is illuminated parallel and close to the interface of the sample and a glass window to get information from single scattered and multiple scattered light. By illuminating the sample with a fiber orientated with the axis parallel to the glass surface, small distances to the source can be examined unimpeded by the illumination beam. The derived information is, for example, not only sensitive to the concentration of the scatterers but also to the size of the scattering particles. We present the setup including the theory to describe the light propagation in the whole configuration using Monte Carlo simulations. The validation has been done with polystyrene microsphere dispersions with different scattering coefficients. As application for the developed setup, we show measurements of different milk samples which vary in concentration of fat, protein, and in fat droplet size during homogenization process. By measuring milk, we show the ability of the sensor to determine information about the scattering phase function without diluting the sample. For sensors in the dairy industry, a measurement with no pre-processing and no diluting of the sample is worthwhile, because this can be used to determine the fat and protein concentration on-line.

scholarly journals On the relationship between the scattering phase function of cirrus and the atmospheric state

2015 ◽  
Vol 15 (2) ◽  
pp. 1105-1127 ◽  
Author(s):  
A. J. Baran ◽  
K. Furtado ◽  
L.-C. Labonnote ◽  
S. Havemann ◽  
J.-C. Thelen ◽  
...  
Keyword(s):  
Phase Function ◽  
Ice Crystals ◽  
The North ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Nwp Model ◽  
Phase Functions ◽  
The Relationship ◽  
Good Agreement

Abstract. This is the first paper to investigate the relationship between the shape of the scattering phase function of cirrus and the relative humidity with respect to ice (RHi, using space-based solar radiometric angle-dependent measurements. The relationship between RHi and the complexity of ice crystals has been previously studied using data from aircraft field campaigns and laboratory cloud chambers. However, to the best of our knowledge, there have been no studies to date that explore this relationship through the use of remotely sensed space-based angle-dependent solar radiometric measurements. In this paper, one case study of semi-transparent cirrus, which occurred on 25 January 2010 off the north-east coast of Scotland, is used to explore the possibility of such a relationship. Moreover, for the first time, RHi fields predicted by a high-resolution numerical weather prediction (NWP) model are combined with satellite retrievals of ice crystal complexity. The NWP model was initialised at midnight, on 25 January 2010, and the mid-latitude RHi field was extracted from the NWP model at 13:00 UTC. At about the same time, there was a PARASOL (Polarization and Anisotropy of Reflectance for Atmospheric science coupled with Observations from a Lidar) overpass, and the PARASOL swath covered the NWP-model-predicted RHi field. The cirrus case was located over Scotland and the North Sea. From the satellite channel based at 0.865 μm, the directionally averaged and directional spherical albedos were retrieved between the scattering angles of about 80 and 130°. An ensemble model of cirrus ice crystals is used to predict phase functions that vary between phase functions that exhibit optical features (referred to as pristine) and featureless phase functions. For each of the PARASOL pixels, the phase function that best minimised differences between the spherical albedos was selected. This paper reports, for this one case study, an association between the most featureless phase function model and the highest values of NWP-predicted RHi (i.e. when RHi > 1.0). For pixels associated with NWP-model-predicted RHi < 1, it was impossible to generally discriminate between phase function models at the 5% significance level. It is also shown that the NWP model prediction of the vertical profile of RHi is in good agreement with dropsonde, in situ measurements and independent aircraft-based physical retrievals of RHi. Furthermore, the NWP model prediction of the cirrus cloud-top height and its vertical extent is also found to be in good agreement with aircraft-based lidar measurements.

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