Combined Experimental-Numerical Approach to Determine Radiation Properties of Particle Suspensions

2013 ◽  
Author(s):  
Jan Marti ◽  
Matthew Roesle ◽  
Aldo Steinfeld
Keyword(s):  
Monte Carlo Model ◽  
Numerical Approach ◽  
Particle Suspensions ◽  
Participating Media ◽  
Radiation Properties ◽  
Radiation Distribution ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Good Agreement ◽  
Sic Particle

A combination of experimental measurements with a numerical model is used to find the intensive radiation properties — extinction coefficient, scattering albedo and scattering phase function — of SiC particle suspensions with varying particle loadings. The experimentally determined angular radiation distribution of irradiated SiC samples is applied to fit a collision-based Monte Carlo model with a continuous participating media defining the particle suspension. A validation case with glass microspheres and Mie theory is used to verify the modeling procedure. Two types of SiC particles with dissimilar optical characteristics are examined and the respective radiation properties are determined for porosities between 0.70–0.95. The extinction coefficients of both types of SiC particle are in good agreement with the dependent scattering correlation of Kaviany and Singh.

Combined Experimental-Numerical Approach to Determine Radiation Properties of Particle Suspensions

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Jan Marti ◽  
Matthew Roesle ◽  
Aldo Steinfeld
Keyword(s):  
Numerical Approach ◽  
Particle Suspensions ◽  
Participating Media ◽  
Extinction Coefficients ◽  
Radiation Properties ◽  
Radiation Distribution ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Good Agreement ◽  
Sic Particle

A combination of experimental measurements with a numerical model is used to find the volume-averaged radiation properties—extinction coefficient, scattering albedo and approximated scattering phase function—of SiC particle suspensions with varying particle loadings. The experimentally determined angular radiation distribution of irradiated SiC samples is applied to fit a collision-based Monte Carlo (MC) model with a continuous participating media defining the particle suspension. A validation case with glass microspheres and Mie theory is implemented to verify the modeling procedure. Two types of SiC particles with dissimilar optical characteristics are examined and the respective radiation properties are determined for particle loadings between 0.05 and 0.30. The extinction coefficients of both types of SiC particle are in good agreement with the dependent scattering correlation of Kaviany and Singh.

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 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.

Combined Radiation and Conduction in Glass Foams

2001 ◽  
Author(s):  
Mark J. Varady ◽  
Andrei G. Fedorov
Keyword(s):  
Heat Transfer ◽  
Foam Layer ◽  
Combustion Gases ◽  
Radiation Properties ◽  
Numerical Iteration ◽  
Flux Approximation ◽  
Scattering Phase ◽  
Bottom Heat ◽  
Scattering Phase Function ◽  
Transfer Properties

Abstract Understanding of heat transfer in glass foams and the development of theoretical tools for predicting heat transfer properties of glass foams is critical to improving the efficiency of glass manufacturing. In this paper, combined radiation and conduction heat transfer in a semitransparent glass foam layer is analyzed. The foam layer is bounded by hot combustion gases on top and glass melt on bottom. Heat transfer is assumed to be one-dimensional perpendicular to the plane-parallel foam layer. A previously developed model is used to calculate effective extinction coefficients and scattering phase function of the foam layer using a void size distribution and assuming all voids to be spherical. These radiation properties are then used along with a Schuster-Schwarzchild two flux approximation to solve the radiative transfer equation (RTE). A method for obtaining the effective thermal conductivity of the foam layer is also presented. The RTE and the energy conservation equations are simultaneously solved using a numerical iteration procedure. The effect of foam thickness and bubble size on the temperature distribution in the foam layer is studied.

A Combined P1 and Monte Carlo Model for Radiative Transfer in Multi-Dimensional Anisotropically Scattering Media

2010 ◽  
Author(s):  
Leonid Dombrovsky ◽  
Wojciech Lipin´ski
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Phase Function ◽  
Monte Carlo Model ◽  
Reference Method ◽  
Computational Time ◽  
Scattering Media ◽  
Combined Method ◽  
Scattering Phase ◽  
Scattering Phase Function

A combined two-step computational method incorporating (1) transport approximation of the scattering phase function, (2) P1 approximation and the finite element method for computing the radiation source function at the first step, and (3) the Monte Carlo method for computing radiative intensity at the second step, is developed. The accuracy of the combined method is examined for model problems involving two multi-dimensional configurations of an anisotropically scattering medium. A detailed analysis is performed for a medium with scattering phase function described by a family of the Henyey–Greenstein functions. The accuracy of the two-step method is assessed by comparing the distribution of the radiative flux leaving the medium to that obtained by a reference complete Monte Carlo method. This study confirms the main results of previous papers on the errors of the two-step solution method. The combined method leads to a significant reduction in computational time as compared to the reference method, by at least 1 order of magnitude. Finally, possible applications of the combined method are briefly discussed.

Combined Radiation and Conduction in Glass Foams

2002 ◽  
Vol 124 (6) ◽  
pp. 1103-1109 ◽  
Author(s):  
Mark J. Varady ◽  
Andrei G. Fedorov
Keyword(s):  
Heat Transfer ◽  
Foam Layer ◽  
Combustion Gases ◽  
Radiation Properties ◽  
Numerical Iteration ◽  
Flux Approximation ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Transfer Properties ◽  
Isotropic Radiation

Understanding of heat transfer in glass foams and the development of theoretical tools for predicting heat transfer properties of glass foams is critical to improving the efficiency of glass manufacturing. In this paper, combined radiation and conduction heat transfer in a semitransparent glass foam layer is analyzed. The foam layer is thin and of the uniform thickness, bounded by hot combustion gases on top and glass melt on bottom, and exposed to isotropic radiation originating from hot refractories. Heat transfer is assumed to be one-dimensional perpendicular to the plane-parallel foam layer. A previously developed model is used to calculate effective extinction coefficients and scattering phase function of the foam layer using a void size distribution and assuming all voids to be spherical. These radiation properties are then used along with a Schuster-Schwarzchild two-flux approximation to solve the radiative transfer equation (RTE). A method for obtaining the effective thermal conductivity of the foam layer is also presented. The RTE and the energy conservation equations are simultaneously solved using a numerical iteration procedure. The effect of foam thickness and bubble size on the temperature distribution in the foam layer is studied.

scholarly journals Measuring Hydrometeors Using a Precipitation Microphysical Characteristics Sensor: Sampling Effect of Different Bin Sizes on Drop Size Distribution Parameters

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Xichuan Liu ◽  
Taichang Gao ◽  
Yuntao Hu ◽  
Xiaojian Shu
Keyword(s):  
Drop Size ◽  
Rain Rate ◽  
Monte Carlo Model ◽  
Rain Gauge ◽  
Sampling Schemes ◽  
Distribution Parameters ◽  
Optimum Sampling ◽  
Simulation Results ◽  
The Impact ◽  
Good Agreement

In order to improve the measurement of precipitation microphysical characteristics sensor (PMCS), the sampling process of raindrops by PMCS based on a particle-by-particle Monte-Carlo model was simulated to discuss the effect of different bin sizes on DSD measurement, and the optimum sampling bin sizes for PMCS were proposed based on the simulation results. The simulation results of five sampling schemes of bin sizes in four rain-rate categories show that the raw capture DSD has a significant fluctuation variation influenced by the capture probability, whereas the appropriate sampling bin size and width can reduce the impact of variation of raindrop number on DSD shape. A field measurement of a PMCS, an OTT PARSIVEL disdrometer, and a tipping bucket rain Gauge shows that the rain-rate and rainfall accumulations have good consistencies between PMCS, OTT, and Gauge; the DSD obtained by PMCS and OTT has a good agreement; the probability of N0, μ, and Λ shows that there is a good agreement between the Gamma parameters of PMCS and OTT; the fitted μ-Λ and Z-R relationship measured by PMCS is close to that measured by OTT, which validates the performance of PMCS on rain-rate, rainfall accumulation, and DSD related parameters.

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