scholarly journals PLUME-MoM 1.0: a new 1-D model of volcanic plumes based on the method of moments

2015 ◽  
Vol 8 (5) ◽  
pp. 3745-3790
Author(s):  
M. de' Michieli Vitturi ◽  
A. Neri ◽  
S. Barsotti
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Method Of Moments ◽  
Computational Cost ◽  
Sensitivity Analyses ◽  
Plume Height ◽  
New Model ◽  
Volcanic Plumes ◽  
Grain Distribution

Abstract. In this paper a new mathematical model for volcanic plumes, named PlumeMoM, is presented. The model describes the steady-state 1-D dynamics of the plume in a 3-D coordinate system, accounting for continuous variability in particle distribution of the pyroclastic mixture ejected at the vent. Volcanic plumes are composed of pyroclastic particles of many different sizes ranging from a few microns up to several centimeters and more. Proper description of such a multiparticle nature is crucial when quantifying changes in grain-size distribution along the plume and, therefore, for better characterization of source conditions of ash dispersal models. The new model is based on the method of moments, which allows description of the pyroclastic mixture dynamics not only in the spatial domain but also in the space of properties of the continuous size-distribution of the particles. This is achieved by formulation of fundamental transport equations for the multiparticle mixture with respect to the different moments of the grain-size distribution. Different formulations, in terms of the distribution of the particle number, as well as of the mass distribution expressed in terms of the Krumbein log scale, are also derived. Comparison between the new moments-based formulation and the classical approach, based on the discretization of the mixture in N discrete phases, shows that the new model allows the same results to be obtained with a significantly lower computational cost (particularly when a large number of discrete phases is adopted). Application of the new model, coupled with uncertainty quantification and global sensitivity analyses, enables investigation of the response of four key output variables (mean and standard deviation (SD) of the grain-size distribution at the top of the plume, plume height and amount of mass lost by the plume during the ascent) to changes in the main input parameters (mean and SD) characterizing the pyroclastic mixture at the base of the plume. Results show that, for the range of parameters investigated, the grain-size distribution at the top of the plume is remarkably similar to that at the base and that the plume height is only weakly affected by the parameters of the grain distribution.

scholarly journals PLUME-MoM 1.0: A new integral model of volcanic plumes based on the method of moments

2015 ◽  
Vol 8 (8) ◽  
pp. 2447-2463 ◽  
Author(s):  
M. de' Michieli Vitturi ◽  
A. Neri ◽  
S. Barsotti
Keyword(s):  
Grain Size ◽  
Standard Deviation ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Method Of Moments ◽  
Integral Model ◽  
Plume Height ◽  
New Model ◽  
Volcanic Plumes ◽  
Grain Distribution

Abstract. In this paper a new integral mathematical model for volcanic plumes, named PLUME-MoM, is presented. The model describes the steady-state dynamics of a plume in a 3-D coordinate system, accounting for continuous variability in particle size distribution of the pyroclastic mixture ejected at the vent. Volcanic plumes are composed of pyroclastic particles of many different sizes ranging from a few microns up to several centimeters and more. A proper description of such a multi-particle nature is crucial when quantifying changes in grain-size distribution along the plume and, therefore, for better characterization of source conditions of ash dispersal models. The new model is based on the method of moments, which allows for a description of the pyroclastic mixture dynamics not only in the spatial domain but also in the space of parameters of the continuous size distribution of the particles. This is achieved by formulation of fundamental transport equations for the multi-particle mixture with respect to the different moments of the grain-size distribution. Different formulations, in terms of the distribution of the particle number, as well as of the mass distribution expressed in terms of the Krumbein log scale, are also derived. Comparison between the new moments-based formulation and the classical approach, based on the discretization of the mixture in N discrete phases, shows that the new model allows for the same results to be obtained with a significantly lower computational cost (particularly when a large number of discrete phases is adopted). Application of the new model, coupled with uncertainty quantification and global sensitivity analyses, enables the investigation of the response of four key output variables (mean and standard deviation of the grain-size distribution at the top of the plume, plume height and amount of mass lost by the plume during the ascent) to changes in the main input parameters (mean and standard deviation) characterizing the pyroclastic mixture at the base of the plume. Results show that, for the range of parameters investigated and without considering interparticle processes such as aggregation or comminution, the grain-size distribution at the top of the plume is remarkably similar to that at the base and that the plume height is only weakly affected by the parameters of the grain distribution. The adopted approach can be potentially extended to the consideration of key particle–particle effects occurring in the plume including particle aggregation and fragmentation.

The effect of total grain-size distribution on the dynamics of turbulent volcanic plumes

2014 ◽  
Vol 394 ◽  
pp. 124-134 ◽  
Author(s):  
Frédéric Girault ◽  
Guillaume Carazzo ◽  
Steve Tait ◽  
Fabrizio Ferrucci ◽  
Édouard Kaminski
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Volcanic Plumes ◽  
Total Grain Size Distribution

Influence of SiO2 Content on Fractal of Grain Distribution in Low Silicon Sinter

2011 ◽  
Vol 391-392 ◽  
pp. 269-273
Author(s):  
Qing Jun Zhang ◽  
Li Mei Jiang ◽  
Wen Ling Mo ◽  
Yu Zhu Zhang
Keyword(s):  
Grain Size ◽  
Fractal Dimension ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Fractal Theory ◽  
Fractal Characteristic ◽  
Important Index ◽  
Grain Distribution

Grain size distribution in the sinter is an important index sign to measure the quality of sinter. In this paper, according to the fractal theory and the contrast experiment of sinter, the fractal characteristic of grain size distribution of sinter with low SiO2is discussed. The relation between the fractal dimension and content of SiO2is proposed. Combine with the SEM graphs of the sinter with low SiO2, the relation between the fractal dimension and microstructure of sinter with low SiO2is also analyzed. Pass to the quantificational description of the grain size distribution of sinter with low SiO2, to predict and optimize the grain size constitution of sinter, and offer a new idea, a new way for the further thorough research of sinter ore.

Variation of the Descriptive Grain Size Distribution Along Cores From the Sebkha of Sidi El Hani, Eastern Tunisia

2022 ◽  
pp. 197-214
Author(s):  
Elhoucine Essefi ◽  
Soumaya Hajji
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Method Of Moments ◽  
Statistical Treatment ◽  
Special Care ◽  
Statistical Parameters ◽  
Sedimentary Dynamics

In this chapter, cores were the object of descriptive classifications of the grain size distribution, which were meant to describe the grain size continuous variability within cores and to correlate between them. The statistical treatment of the crude data was done on the basis of two different methods (the method of moments statistics and the method of inclusive graphic statistics) to compute statistical parameters of the grain size distribution such as mean and median. The correlations between cores were done on the basis of sand/silt/clay percentages. Even though it has given special care to test different methods of studying the grain size distribution, this study has not deviated from its primary purpose of investigating the filling of the playa; correlations between different cores were meant to infer their sedimentary dynamics.

scholarly journals Advanced Numerical Modeling of Sediment Transport in Gravel-Bed Rivers

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 550 ◽  
Author(s):  
Van Bui ◽  
Minh Bui ◽  
Peter Rutschmann
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Morphological Changes ◽  
Relative Size ◽  
Size Fraction ◽  
New Model ◽  
Gravel Bed ◽  
Gravel Bed Rivers

Understanding the alterations of gravel bed structures, sediment transport, and the effects on aquatic habitat play an essential role in eco-hydraulic and sediment transport management. In recent years, the evaluation of changes of void in bed materials has attracted more concern. However, analyzing the morphological changes and grain size distribution that are associated with the porosity variations in gravel-bed rivers are still challenging. This study develops a new model using a multi-layer’s concept to simulate morphological changes and grain size distribution, taking into account the porosity variabilities in a gravel-bed river based on the mass conservation for each size fraction and the exchange of fine sediments between the surface and subsurface layers. The Discrete Element Method (DEM) is applied to model infiltration processes and to confirm the effects of the relative size of fine sediment to gravel on the infiltration depth. Further, the exchange rate and the bed porosity are estimated while using empirical formulae. The new model was tested on three straight channels. Analyzing the calculated results and comparing with the observed data show that the new model can successfully simulate sediment transport, grain sorting processes, and bed change in gravel-bed rivers.

scholarly journals Grain-size distribution analysis of Quaternary sediments from the southern part of the Lodz region in Poland: a computational-methods approach

Geologos ◽  
2011 ◽  
Vol 17 (4) ◽  
pp. 205-219 ◽  
Author(s):  
Lucyna Wachecka-Kotkowska ◽  
Paweł Kotkowski
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Computational Methods ◽  
Method Of Moments ◽  
Linear Interpolation ◽  
Unconsolidated Sediments ◽  
Distribution Analysis ◽  
Quaternary Sediments ◽  
Average Grain Size

Grain-size distribution analysis of Quaternary sediments from the southern part of the Lodz region in Poland: a computational-methods approachEighteen samples of Quaternary unconsolidated sediments from the Piotrków Plateau and the Radomsko Hills in central Poland have been analysed for their average grain size, sorting, skewness and kurtosis. The analysis was carried out by seven computational methods of interpolation and nine extrapolation methods. It appears that linear interpolation, the traditional method (DOS), and the Josek and Gradistat Programs give comparable results, but that quadratic interpolation and the method of moments should not be applied since they yield unreliable results. The method of moments gives unduly high or unduly low parameter values because of the application of different, i.e. incomparable measures in the applied formulae. It should be stressed that only extrapolation provides, if performed under the right conditions, the possibility to determine some parameters, in particular skewness values.

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