scholarly journals An investigation of low-energy photon reflection from the iron target

2004 ◽  
Vol 19 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Srpko Markovic ◽  
Rodoljub Simovic ◽  
Vladan Ljubenov
Keyword(s):  
Free Surface ◽  
Thomson Scattering ◽  
Photon Flux ◽  
Scattered Photon ◽  
Scattering Method ◽  
Scattering Function ◽  
Albedo Problem ◽  
Low Energies ◽  
Homogeneous Plane ◽  
Comparison Of The Results

For the photon transport kernel in form of the Thomson scattering function and a restrictive photon diffusion directed only toward free surface, several exact expressions of back scattered fluxes are demonstrated. The solving approach was established on a lemma proved by Placzek combined with the Fourier analytic inversion technique or the order of scattering method. Albedo problem in case of the homogeneous plane shield of iron subjected to the photons normally incident on the free surface is treated. Comparison of the results obtained by the analytical and Monte Carlo methods for the reflection of 40 and 60 keV photons from iron target confirms the domination of the single scattered photon flux and the strong influence of the scattering function anisotropy in reflection process at low energies.

scholarly journals Non-equilibrium Studies in Switching Arc Plasmas in Japan

2017 ◽  
Vol 4 (3) ◽  
pp. 225-233
Author(s):  
Y. Tanaka ◽  
K. Tomita ◽  
Y. Inada ◽  
A. Kumada ◽  
K. Hidaka ◽  
...  
Keyword(s):  
Research Work ◽  
Thomson Scattering ◽  
Field Application ◽  
Scattering Method ◽  
Equilibrium Studies ◽  
Comparison Results ◽  
Experimental Approaches ◽  
Arc Plasmas ◽  
Equilibrium Simulation ◽  
Non Equilibrium

This paper briefly introduce research work examples of non-equilibrium studies in switching arcs. In understanding arc behavior, one often assumes local thermodynamic equilibrium (LTE) condition in the arc plasma. However, actual arc plasmas are not completely and not always in LTE state because of strong temperature change temporally and spatially, and high electric field application etc. Recently, we have a collaboration work in numerical simulations and experimental approaches for decaying arcs without LTE assumption. First, our numerical model is presented for decaying arcs without chemical equilibrium assumption. Secondly, two experimental methods are introduced for measuring electron density in decaying arcs without LTE assumption: Laser Thomson Scattering method and the Schack-Hartmann method. Finally, comparison results is shown between the LTE simulation, the chemically non-equilibrium simulation, and the above experimental measurements.

Measurement of electron temperature in plasma using Thomson scattering method

2003 ◽  
Author(s):  
T. Shibuya ◽  
S. Tada ◽  
K. Kumita ◽  
A. Tonegawa ◽  
M. Wakaki ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Thomson Scattering ◽  
Scattering Method

Oil Scoop Simulation and Analysis Using CFD and SPH

2016 ◽  
Author(s):  
Evgenia Korsukova ◽  
Arno Kruisbrink ◽  
Hervé Morvan ◽  
Paloma Paleo Cageao ◽  
Kathy Simmons
Keyword(s):  
Free Surface ◽  
Coming Out ◽  
High Speed ◽  
Direct Injection ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Particle Collision ◽  
Engine Cooling ◽  
Comparison Of The Results ◽  
Oil Jet

The process of rotating scoops capturing oil coming out of a stationary jet nozzle was simulated with CFD (Computational Fluid Dynamics) and SPH (Smoothed Particles Hydrodynamics). The aim was to determine the efficiency of the oil capture, and the effects of varying parameters such as angular velocity of the scoops, the speed and direction of the oil jet and arrangement of the oil jets (in case of more than one jet). This configuration is found in engine cooling and/or lubricating systems: where oil scoops are used to deliver the oil to the places where direct injection is not possible. In CFD both two- and three-dimensional geometries were used; the models were then run using the Volume of Fluid method with the SST k-ω model. SPH is a meshless Lagrangian method for flow simulation, where the fluid is represented by particles. In addition to the conventional SPH formulation, three main highlights were introduced in the current work: the rotating ghost particles (representing the scoops), the particle collision model (Korzilius et al., 2014) and source and sink particles (representing the oil coming out from the nozzle and captured at the scoops respectively). The simulations allowed for the observation of the free surface of the oil jet (before, during, and after cutting of the jet by the blade), the pressure and velocity fields for the air and oil, and the efficiency of the system, defined as the ratio of oil outflow (via scoops) and inflow. This is a comparative study between CFD and SPH, where SPH is explored for a lubrication of a high-speed rotating component. The results of CFD and SPH, in particular the oil free surface and the efficiency, were then compared and validated with experimental results, demonstrating good agreement. The setup and comparison of the results obtained with the described techniques are presented in this work.

scholarly journals Dense flows of cohesive granular materials

2008 ◽  
Vol 596 ◽  
pp. 21-47 ◽  
Author(s):  
PIERRE G. ROGNON ◽  
JEAN-NOËL ROUX ◽  
MOHAMED NAAÏM ◽  
FRANÇOIS CHEVOIR
Keyword(s):  
Free Surface ◽  
Rheological Behaviour ◽  
Constitutive Law ◽  
Contact Network ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Plane Shear ◽  
Cohesive Forces ◽  
Homogeneous Plane ◽  
Dense Flows

Using molecular dynamic simulations, we investigate the characteristics of dense flows of model cohesive grains. We describe their rheological behaviour and its origin at the scale of the grains and of their organization. Homogeneous plane shear flows give access to the constitutive law of cohesive grains which can be expressed by a simple friction law similar to the case of cohesionless grains, but intergranular cohesive forces strongly enhance the resistance to the shear. Then we show the consequence on flows down a slope: a plugged region develops at the free surface where the cohesion intensity is the strongest. Moreover, we measure various indicators of the microstructure within flows which evidence the aggregation of grains owing to cohesion and we analyse the properties of the contact network (force distributions and anisotropy). This provides new insights into the interplay between the local contact law, the microstructure and the macroscopic behavior of cohesive grains. Movies are available with the online version of the paper.

A Preliminary Study on the Simulation of Vortex Flow in Pump Intake Based on LBM-VOF-LES Combined Model

2021 ◽  
Vol 143 (5) ◽  
Author(s):  
Miao Guo ◽  
Xuelin Tang ◽  
Xiaoqin Li ◽  
Fujun Wang ◽  
Xiaoyan Shi
Keyword(s):  
Free Surface ◽  
Lattice Boltzmann ◽  
Vortex Flow ◽  
Solid Wall ◽  
Flow Patterns ◽  
Vof Method ◽  
Surface Model ◽  
Strain Rate Tensor ◽  
Comparison Of The Results ◽  
Les Model

Abstract In this paper, the lattice Boltzmann method-large eddy simulation (LBM-LES) model was combined with the volume of fluid (VOF) method and used to simulate vortex flow in a typical pump intake. The strain rate tensor in the LES model is locally calculated utilizing nonequilibrium moments based on Chapman–Enskog expansion, and the bounce-back scheme is used for nonslip condition on the solid wall and VOF method for the free surface. The evolution of all kinds of cells on the free surface is based on the mass exchange in the VOF method, i.e., lattice Boltzmann-single phase (LB-SP) free surface model. The introduction of the external force terms is established through adding corresponding expressions on the right of the lattice Boltzmann equation (LBE), and by modifying the velocity. The predicted vortex flow patterns (core location and strength of the vortex) and velocity correlate with the experiments undertaken with the physical model. A comparison of the results demonstrates the feasibility and stability of the model and the numerical method in predicting vortex flows inside pump intakes. The model developed and presented in this paper provides a new analysis method of vortex flow patterns in pump intake from a mesoscopic perspective, enriches the relevant technologies, and makes corresponding contributions to further engineering applications.

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