LIQUID-SOLID TRANSITION IN BIDISPERSE GRANULATES

2001 ◽  
Vol 04 (04) ◽  
pp. 379-388 ◽  
Author(s):  
STEFAN LUDING
Keyword(s):  
Distribution Function ◽  
Correlation Function ◽  
Volume Fraction ◽  
Size Distribution Function ◽  
Dissipative Systems ◽  
Simulation Data ◽  
Ordering Effects ◽  
Theoretical Predictions ◽  
Total Volume Fraction ◽  
Simulation Results

Simulation results of dense granulates with particles of different sizes are compared with theoretical predictions concerning the mixture pressure. An effective correlation function is computed which depends only on the total volume fraction and on the dimensionless width of the size-distribution function. From simulation data of elastic and weakly dissipative systems, one can predict how much disorder (size-dispersity) is necessary to avoid ordering effects due to crystallization. Finally, a global equation of state is proposed, which unifies both the dilute, disordered gas/fluid and the dense, solid regime.

scholarly journals SPATIAL STATISTICS FOR SIMULATED PACKINGS OF SPHERES

2011 ◽  
Vol 20 (3) ◽  
pp. 203 ◽  
Author(s):  
Alexander Bezrukov ◽  
Dietrich Stoyan ◽  
Monika Bargieł
Keyword(s):  
Distribution Function ◽  
Correlation Function ◽  
Spatial Statistics ◽  
Volume Fraction ◽  
Pair Correlation ◽  
Simulation Methods ◽  
Coordination Numbers ◽  
Contact Distribution ◽  
Contact Distribution Function ◽  
Random Packings

This paper reports on spatial-statistical analyses for simulated random packings of spheres with random diameters. The simulation methods are the force-biased algorithm and the Jodrey-Tory sedimentation algorithm. The sphere diameters are taken as constant or following a bimodal or lognormal distribution. Standard characteristics of spatial statistics are used to describe these packings statistically, namely volume fraction, pair correlation function of the system of sphere centres and spherical contact distribution function of the set-theoretic union of all spheres. Furthermore, the coordination numbers are analysed.

Domain-Spatial Correlation Function of Spherulitic Domain Evolution in Polymer Films

1997 ◽  
Vol 481 ◽  
Author(s):  
Tao Huang ◽  
Tomohiro Tsuji ◽  
M. R. Kamal ◽  
A. D. Rey
Keyword(s):  
Correlation Function ◽  
Spatial Correlation ◽  
Volume Fraction ◽  
Domain Size ◽  
Nucleation And Growth ◽  
Size Distribution Function ◽  
Domain Growth ◽  
Spatial Correlation Function ◽  
Time Dependent Domain ◽  
Spatio Temporal

ABSTRACTWe present a new theoretical model of nucleation and growth in term of a novel domainspatial correlation function. This model probes the patterns and spatio-temporal evolution of nucleation and growth process and agrees very well with experimental data. The dynamic domain-spatial correlation function directly and simultaneously explores the transformed volume fraction, the time-dependent domain size distribution function, and the spatial correlation function of domain core centers for the entire process, including the post-nucleation, domain growth and grain formation stages.

FLEXIBLE DISSIPATIVE PARTICLE DYNAMICS

2010 ◽  
Vol 21 (09) ◽  
pp. 1129-1148 ◽  
Author(s):  
Z. G. HUANG ◽  
T. M. YUE ◽  
K. C. CHAN ◽  
Z. N. GUO
Keyword(s):  
Distribution Function ◽  
Radial Distribution Function ◽  
Radial Distribution ◽  
Weighting Function ◽  
Local Density ◽  
Dissipative Particle Dynamics ◽  
Particle Dynamics ◽  
Theoretical Predictions ◽  
Simulation Results ◽  
Thermodynamic Variables

Dissipative Particle Dynamics (DPD) has been recognized as a powerful tool for simulating the dynamics of complex fluids on a mesoscopic scale. However, owing to the rigid thermodynamic behavior of the standard model, it has limitations when applied to real systems. Although refined models have been developed to improve the thermodynamic consistency of DPD, they are not without limitations and deficiencies. In this paper, we extend the power of DPD beyond its traditional limits so that it can cope with systems where temperature and pressure changes occur. This is accomplished using a refined model termed Flexible DPD (FDPD), which allows the equation of state (EOS) to be given in priori. As a basis for the development of FDPD, the generalized expression for the thermodynamic variables is derived by solving the Langevin equation of a particle. It is found that the radial distribution function will be approximately invariant under variable transformation if the action range of potential is changed appropriately according to local density. With this invariant character of RDF, and by choosing the force functions to be variable separable, equations relating thermodynamic variables with the functions for DPD interactions are derived, and the weighting function for achieving thermodynamic is designed correspondingly. A case study on the validation of the FDPD method has been undertaken on the adiabatic compression of N2 gas. The simulation results were compared with the theoretical predictions as well as to the simulation results of the ordinary DPD method. The invariant of radial distribution function is justified by the results of the simulation.

The Effect of a Non-Equipartition of Energy on Multi-component Flows

2002 ◽  
Vol 759 ◽  
Author(s):  
J. E. Galvin ◽  
S. R. Dahl ◽  
C. M. Hrenya
Keyword(s):  
Hard Sphere ◽  
Binary Systems ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Simple Shear Flow ◽  
Simulation Data ◽  
Theoretical Predictions ◽  
Simulation Results ◽  
Equipartition Of Energy ◽  
Accurate Stress

ABSTRACTRapid granular flows of two species with different material densities are examined via three-dimensional, hard-sphere simulations of simple shear flow. Simulation results are compared with existing theories for binary systems based on the kinetic theory analogy. The comparison between simulation data and theoretical predictions indicate that although non-equipartition is observed and well-predicted by the theory which accounts for its effects, the influence of non-equipartition on stress predictions is fairly small. The influence of non-Maxwellian effects, however, are critical for accurate stress predictions.

ANSYS-CFX simulation of the SRBTL test loop core with nanofluid coolant

Kerntechnik ◽  
2021 ◽  
Vol 86 (6) ◽  
pp. 445-453
Author(s):  
B. Khonsha ◽  
G. Jahanfarnia ◽  
K. Sepanloo ◽  
M. Nematollahi ◽  
I. Khonsha
Keyword(s):  
Heat Transfer ◽  
Volume Fraction ◽  
Pure Water ◽  
Reactor Core ◽  
Simulation Data ◽  
Ansys Cfx ◽  
Test Loop ◽  
Water Based ◽  
Simulation Results ◽  
Good Agreement

Abstract In the present study, CFD calculations are presented for the three types of water-based nanofluids Al2O3/water, CuO/water and TiO2/water with 0.1% volume fraction. These calculations are done with ANSYS-CFX and as geometry the SRBTL test loop as scaled down test loop for a VVER-1000 reactor core design is used. The goal of this study is to evaluate the CFD program against the SRBTL test loop core as a scaled core for applying water-based nanofluids as coolant. ANSYS-CFX simulation data are validated against the RELAP5/MOD3.2 simulation data for pure water. This comparison shows a good agreement. The simulation results for the nanofluids and water including Re number, temperature, viscosity, pressure drop and heat transfer coefficient through the SRBTL test loop core are compared. The results of the comparisons show that the SRBTL test loop core is suitable to extract experimental data of water-based nanofluids for using them as coolant in the VVER-1000 reactor.

Moire Fringes on Precipitates in Quenched and Aged Beryllium

1968 ◽  
Vol 26 ◽  
pp. 426-427
Author(s):  
F. J. Fraikor ◽  
A. W. Brewer
Keyword(s):  
Ternary Phase ◽  
Volume Fraction ◽  
Age Hardening ◽  
Orientation Relationships ◽  
Solute Content ◽  
Moiré Fringes ◽  
Moire Patterns ◽  
Total Volume Fraction ◽  
Diffraction Patterns ◽  
Moiré Patterns

A number of investigators have examined moire patterns on precipitate particles in various age-hardening alloys. For example, Phillips has analyzed moire fringes at cobalt precipitates in copper and Von Heimendahl has reported on moire fringes in the system Al-Au. Recently, we have observed moire patterns on impurity precipitates in beryllium quenched in brine from 1000°C and aged at various temperatures in the range of 500-800°C. This heat treatment of beryllium rolled from vacuum cast ingots produces the precipitation of both an fee ternary phase, AlFeBe4, and an hcp binary phase, FeBe11. However, unlike a typical age-hardening alloy, the solute content of this material is low (less than 1000 ppm of Fe and 600 ppm of Al) and hence the total volume fraction of precipitates is small. Therefore there is some difficulty in distinguishing the precipitates and their orientation relationships with the beryllium matrix since the weak precipitate spots generally do not appear on the diffraction patterns.

scholarly journals Research on Cavitation of the Rotating-Sleeve Distributing Flow System Considering Different Cam Groove Profiles

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2139
Author(s):  
Shanxiao Du ◽  
Jichao Hong ◽  
Hongxin Zhang ◽  
Qinghai Zhao ◽  
Tiezhu Zhang ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Flow System ◽  
Volumetric Efficiency ◽  
Piston Pump ◽  
Operating Frequency ◽  
Cavitation Model ◽  
Pump Chamber ◽  
Orthogonal Experiments ◽  
Simulation Results ◽  
Further Development

Reciprocating piston pumps are widely used in various fields, such as automobiles, ships, aviation, and engineering machinery. Conventional reciprocating piston pump distributing flow (RPPDF) systems have the disadvantages of a loose structure and low volumetric efficiency, as well as affected positively by the operating frequency. In this paper, a novel rotating-sleeve distributing flow (RSDF) system is presented for bridging these drawbacks, as well as structurally improved to overcome the inoperable and challenging problems in oil intake and discharge found in the experiment. Moreover, the Singhal cavitation model specifically for the RSDF system and four-cam groove profiles (CGPs) is established. To find the most suitable CGP to reduce the RSDF’s cavitation, the cavitation of the RSDF system was investigated, combining with simulations by taking into account the gap among the rotating sleeve, the pump chamber, and experiments on four presented CGPs. Simulation results based on vapor volume fraction, cavitation ratio, and volumetric efficiency show that the linear profile’s cavitation is the weakest. Finally, the correctness of the simulation is verified through orthogonal experiments. This research is of great significance to the further development of the RSDF system; more important, it has great potential to promote the reform of the RPPDF method.

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