Crack-particle interaction in a two-phase composite Part II: crack deflection

1995 ◽  
Vol 73 (1) ◽  
pp. 81-92 ◽  
Author(s):  
P. Lipetzky ◽  
Z. Knesl
Keyword(s):  
Particle Interaction ◽  
Crack Deflection ◽  
Composite Part ◽  
Two Phase

ON THE CAUCHY PROBLEM FOR THE GYRO-WATER-BAG MODEL

2011 ◽  
Vol 21 (09) ◽  
pp. 1839-1869 ◽  
Author(s):  
NICOLAS BESSE
Keyword(s):  
Fluid Model ◽  
Particle Interaction ◽  
Direct Consequence ◽  
Point Of View ◽  
Magnetized Plasma ◽  
Geometric Invariant ◽  
Two Phase ◽  
Bag Model ◽  
The Cauchy Problem ◽  
Kinetic Features

In this paper we prove the existence and uniqueness of classical solution for a system of PDEs recently developed in Refs. 60, 8, 10 and 11 to modelize the nonlinear gyrokinetic turbulence in magnetized plasma. From the analytical and numerical point of view this model is very promising because it allows to recover kinetic features (wave–particle interaction, Landau resonance) of the dynamic flow with the complexity of a multi-fluid model. This model, called the gyro-water-bag model, is derived from two-phase space variable reductions of the Vlasov equation through the existence of two underlying invariants. The first one, the magnetic moment, is adiabatic and the second, a geometric invariant named "water-bag", is exact and is just the direct consequence of the Liouville theorem.

Numerical Simulation of Grinding and Drying Performance of a Fluid-Energy Lignite Mill

2000 ◽  
Vol 123 (2) ◽  
pp. 303-310 ◽  
Author(s):  
J. Anagnostopoulos ◽  
G. Bergeles ◽  
B. Epple ◽  
P. Stegelitz
Keyword(s):  
Numerical Algorithm ◽  
Power Plants ◽  
Two Phase Flow ◽  
Dispersion Model ◽  
Particle Interaction ◽  
Particle Dispersion ◽  
Special Treatment ◽  
Phase Flow ◽  
Two Phase ◽  
Large Power

A numerical algorithm is developed for a detailed 3D simulation of the two-phase flow field in fluid-energy mills used for pulverization and drying of fossil fuels in large power plants. The gas phase equations are solved using finite differences and the control volume method, whereas a Lagrangian formulation with a stochastic particle dispersion model is adopted for the particulate phase. Fluid-particle interaction is taken into account to calculate the mass, momentum, and heat transfer between phases. Advanced numerical techniques for partially-blocked cells and local grid refinement have been utilized to achieve an accurate representation of the domain geometry and to enhance the accuracy of the results. Particle collisions, fragmentation mechanism, and moisture evaporation are simulated by corresponding models, whereas the special treatment employed for the rotating fan region provides the capability to solve the two-phase flow simultaneously in the entire rotating and nonrotating mill domain. The flow and the operation characteristics of a recently developed lignite mill are measured, and the numerical algorithm is used to predict the mill performance under various inlet profiles of the fuel mass flow rate. The predicted results are reasonable, and in agreement with the available measurements and observations, thus offering a deeper insight into the complex dynamic and thermal behavior of the two-phase flow in the mill.

What Can Be Learned From LES of Particle-Laden Turbulent Flows (Invited Talk)

2002 ◽  
Author(s):  
Olivier Simonin ◽  
Kyle D. Squires
Keyword(s):  
Turbulent Flows ◽  
Broad Class ◽  
Particle Interaction ◽  
Turbulent Channel Flow ◽  
Computational Techniques ◽  
Small Particles ◽  
Two Phase Flows ◽  
Two Phase ◽  
Eddy Simulation ◽  
Large Eddy

Numerical simulation continues to evolve as an important tool in the analysis and prediction of two-phase turbulent flows. Computations are playing an increasingly important role as both a means for study of the fundamental interactions governing a process or flow, as well as forming the backbone for engineering predictions of physical systems. At a practical level, computations for engineering applications continue to rely on solution of a statistically-averaged equation set. Many of the statistical correlations requiring closure in Reynolds-averaged models are often difficult or impossible to measure in experimental investigations of two-phase flows. Computational techniques that directly resolve turbulent eddies are an important component in evaluating closure models, while at the same time offering a useful approach for basic studies of fundamental interactions. The focus of the lecture is on numerical prediction and study of turbulent two-phase flows using computational techniques such as Large Eddy Simulation (LES) that directly resolve the large, energy-containing scales of the turbulent motion. Within this broad class, the subset of two-phase flows in which a dispersed phase is comprised of small particles and is present at low volume fractions is of primary interest, using Lagrangian computational techniques for the prediction of trajectories of a large ensemble of discrete particles. The scope of such an approach considered is on systems in which the ensemble comprising the particulate phase is large enough that direct resolution of the flow in the vicinity of each particle is not feasible and, consequently, models on fluid-particle interfacial transfer and particle-particle interaction must be imposed. The focus of the lecture is on numerical prediction and study of turbulent two-phase flows using computational techniques such as Large Eddy Simulation (LES) that directly resolve the large, energy-containing scales of the turbulent motion. Within this broad class, the subset of two-phase flows in which a dispersed phase is comprised of small particles and is present at low volume fractions is of primary interest, using Lagrangian computational techniques for the prediction of trajectories of a large ensemble of discrete particles. The scope of such an approach considered is on systems in which the ensemble comprising the particulate phase is large enough that direct resolution of the flow in the vicinity of each particle is not feasible and, consequently, models on fluid-particle interfacial transfer and particle-particle interaction must be imposed. The advantages and limitations of such a technique are first considered and its accuracy is evaluated by comparison with discrete particle simulations coupled with fluid turbulence predictions obtained using DNS (understood in the present context as solution of the carrier-phase flow without the use of explicit subgrid turbulence models). An overview and examples of the application of LES to prediction and scientific study of dispersed, turbulent two-phase flows is then presented for several representative flow configurations: statistically stationary and decaying particle-laden isotropic turbulence, homogeneous shear flow, fully-developed turbulent channel flow, and turbulent particle-laden round jet. In such flows, the detailed description possible using LES enables in-depth evaluations of statistical and structural features. In particular, the role of inter-particle collision in turbulent channel flow and more recent efforts focused on exploration and analysis of the spatial structure of the particle concentration and velocity fields in homogeneous turbulence are discussed.

Maximum entropy-based stochastic micromechanical model for a two-phase composite considering the inter-particle interaction effect

2015 ◽  
Vol 226 (9) ◽  
pp. 3069-3084 ◽  
Author(s):  
H. H. Zhu ◽  
Q. Chen ◽  
J. W. Ju ◽  
Z. G. Yan ◽  
F. Guo ◽  
...  
Keyword(s):  
Maximum Entropy ◽  
Interaction Effect ◽  
Micromechanical Model ◽  
Particle Interaction ◽  
Two Phase

GLOBAL WEAK SOLUTIONS FOR THE RELATIVISTIC WATERBAG CONTINUUM

2012 ◽  
Vol 22 (01) ◽  
pp. 1150001 ◽  
Author(s):  
NICOLAS BESSE
Keyword(s):  
Phase Space ◽  
Fluid Model ◽  
Particle Interaction ◽  
Direct Consequence ◽  
Two Phase ◽  
Kinetic Formulation ◽  
Resonant Wave ◽  
Defect Measure ◽  
Statistical Distribution Function ◽  
Kinetic Features

In this paper we consider the relativistic waterbag continuum which is a useful PDE for collisionless kinetic plasma modeling recently developed in Ref. 11. The waterbag representation of the statistical distribution function of particles can be viewed as a special class of exact weak solution of the Vlasov equation, allowing to reduce this latter into a set of hydrodynamic equations (with the complexity of a multi-fluid model) while keeping its kinetic features (Landau damping and nonlinear resonant wave-particle interaction). These models are very promising because they are very useful for analytical theory and numerical simulations of laser-plasma and gyrokinetic physics.10–16, 56, 57 The relativistic waterbag continuum is derived from two phase-space variable reductions of the relativistic Vlasov–Maxwell equations through the existence of two underlying exact invariants, one coming from physics properties of the dynamics is the canonical transverse momentum, and the second, named the "water-bag" and coming from geometric property of the phase-space is just the direct consequence of the Liouville Theorem. In this paper we prove the existence and uniqueness of global weak entropy solutions of the relativistic waterbag continuum. Existence is based on vanishing viscosity method and bounded variations (BV) estimates to get compactness while proof of uniqueness relies on kinetic formulation of the relativistic waterbag continuum and the associated kinetic entropy defect measure.

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