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.

Cooling Flow Simulation in the Enclosure of Mobile Generator

2004 ◽  
Author(s):  
J. Xie ◽  
R. S. Amano
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Rate ◽  
Hot Spots ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Cooling Flow ◽  
Simulation Results ◽  
Design Factors ◽  
Flow Study

A thermal and airflow simulation model is developed for three-dimensional cooling flow study of ventilation and heat transfer inside a mobile generator’s enclosure. The purpose of this design is to achieve better sound attenuation while keeping proper cooling of the engine and generator. This paper focuses its objectives on the adjustment and improvement of cooling performances of some design factors like vent size, vent positions, fan’s flow rate and airflow route based on the CFD approach. A zero-equation HVAC turbulence model was employed and the simulation results were compared with the standard k-ε model. Numerical results show that the proper distribution in the intake vents helps in achieving uniform cooling flow distributions by avoiding the occurrence of hot spots on the engine and generator surfaces. Pressure drop through muffler and radiator are both important factors. Effective flow path arrangement is also found to be one of the most fatal factors in the thermal and noise management.

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 Equation of State of Four- and Five-Dimensional Hard-Hypersphere Mixtures

Entropy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 469 ◽  
Author(s):  
Mariano López de Haro ◽  
Andrés Santos ◽  
Santos B. Yuste
Keyword(s):  
Molecular Dynamics ◽  
Monte Carlo Simulation ◽  
Equation Of State ◽  
Hard Sphere ◽  
Virial Coefficient ◽  
Three Dimensional ◽  
The Other ◽  
Third Virial Coefficient ◽  
Simulation Results ◽  
The One

New proposals for the equation of state of four- and five-dimensional hard-hypersphere mixtures in terms of the equation of state of the corresponding monocomponent hard-hypersphere fluid are introduced. Such proposals (which are constructed in such a way so as to yield the exact third virial coefficient) extend, on the one hand, recent similar formulations for hard-disk and (three-dimensional) hard-sphere mixtures and, on the other hand, two of our previous proposals also linking the mixture equation of state and the one of the monocomponent fluid but unable to reproduce the exact third virial coefficient. The old and new proposals are tested by comparison with published molecular dynamics and Monte Carlo simulation results and their relative merit is evaluated.

Numerical simulation of flow patterns in the forebay and suction sump of Tianshan pumping station

2014 ◽  
Vol 9 (4) ◽  
pp. 519-525
Author(s):  
Jun Li ◽  
Yongmei Cao ◽  
Chuanchang Gao
Keyword(s):  
Numerical Simulation ◽  
Yellow River ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Flow Patterns ◽  
The Yellow River ◽  
Technical Improvement ◽  
Pumping Station ◽  
Turbulence Flow ◽  
Simulation Results

Tianshan Pumping Station takes water from the Yellow River. A three-dimensional (3D) mathematical model of turbulence flow patterns in the forebay and suction sump was developed and a 3D turbulent flow simulation technique applied to numerical calculation of the flow pattern characteristics in both the original and rebuilt forebays of the pumping station. The numerical simulation results were analyzed and contrasted. The results showed that, with technical improvement, surface backflow was avoided, and bottom velocity in the forebay was increased while bottom velocity in the suction sump was unchanged. Because of this, there was no sediment deposition in the bottom of the forebay, and flow velocities in the forebay and suction sump were more evenly distributed.

scholarly journals Recovering the Damping Rates of Cyclotron Damped Plasma Waves from Simulation Data

2017 ◽  
Vol 21 (4) ◽  
pp. 947-980 ◽  
Author(s):  
Cedric Schreiner ◽  
Patrick Kilian ◽  
Felix Spanier
Keyword(s):  
Three Dimensional ◽  
Low Frequency ◽  
Plasma Waves ◽  
Simulation Data ◽  
Simple Method ◽  
Particle In Cell ◽  
Frequency Plasma ◽  
Damping Rate ◽  
Theoretical Predictions ◽  
Dimensional Simulation

AbstractPlasma waves with frequencies close to the particular gyrofrequencies of the charged particles in the plasma lose energy due to cyclotron damping. We briefly discuss the gyro-resonance of low frequency plasma waves and ions particularly with regard to particle-in-cell (PiC) simulations. A setup is outlined which uses artificially excited waves in the damped regime of the wave mode's dispersion relation to track the damping of the wave's electromagnetic fields. Extracting the damping rate directly fromthe field data in real or Fourier space is an intricate and non-trivial task. We therefore present a simple method of obtaining the damping rate Γ from the simulation data. This method is described in detail, focusing on a step-by-step explanation of the course of actions. In a first application to a test simulation we find that the damping rates obtained from this simulation generally are in good agreement with theoretical predictions. We then compare the results of one-, two- and three-dimensional simulation setups and simulations with different physical parameter sets.

scholarly journals 2D and 3D Potential Flow Simulation around NACA 0012 Airfoil with Ground Effect

2021 ◽  
Author(s):  
YavuzHakan Ozdemir ◽  
Baris Barlas
Keyword(s):  
Boundary Element ◽  
Potential Flow ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Ground Effect ◽  
Physical Problems ◽  
Constant Strength ◽  
Simulation Results ◽  
Naca 0012 ◽  
2D And 3D

Abstract The purpose of this paper is to develop a Boundary Element Based Method (BEM) for determining the steady potential about two and three dimensional airfoil. The numerical investigation of NACA 0012 airfoil with using Boundary Element Method is utilized. Two different physical problems of the NACA 0012 airfoil are examined: potential flow around airfoil in an unbounded fluid and potential flow prediction with ground effect. Computation of potential flow around the airfoil is investigated by the mixed constant strength source and constant strength dipole based panel method. Boundary Element Code is written in FORTRAN. To check the accuracy of the 2D boundary element based code, the validation studies are carried out by comparing the present results obtained for the NACA 0012 airfoil from the XFoil and other published simulation results. 3D results are also evaluating with the available experimental and other numerical simulation results. The numerical outcomes are examined in terms of pressure distribution and lifting force on the foil.

Design of finite-time guidance law based on observer and head-pursuit theory

2021 ◽  
pp. 095441002098456
Author(s):  
Chenqi Zhu
Keyword(s):  
Finite Time ◽  
Three Dimensional ◽  
Hypersonic Vehicle ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Reaching Law ◽  
Guidance Law ◽  
Fast Power ◽  
Simulation Results ◽  
Guidance Laws

In order to improve the guiding accuracy in intercepting the hypersonic vehicle, this article presents a finite-time guidance law based on the observer and head-pursuit theory. First, based on a two-dimensional model between the interceptor and target, this study applies the fast power reaching law to head-pursuit guidance law so that it can alleviate the chattering phenomenon and ensure the convergence speed. Second, target maneuvers are considered as system disturbances, and the head-pursuit guidance law based on an observer is proposed. Furthermore, this method is extended to a three-dimensional case. Finally, comparative simulation results further verify the superiority of the guidance laws designed in this article.

scholarly journals Prandtl Number in Classical Hard-Sphere and One-Component Plasma Fluids

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 821
Author(s):  
Sergey Khrapak ◽  
Alexey Khrapak
Keyword(s):  
Prandtl Number ◽  
Hard Sphere ◽  
Solid Phase ◽  
Freezing Point ◽  
Three Dimensional ◽  
Order Unity ◽  
Strongly Coupled ◽  
Dielectric Fluids ◽  
Weakly Coupled ◽  
Component Plasma

The Prandtl number is evaluated for the three-dimensional hard-sphere and one-component plasma fluids, from the dilute weakly coupled regime up to a dense strongly coupled regime near the fluid-solid phase transition. In both cases, numerical values of order unity are obtained. The Prandtl number increases on approaching the freezing point, where it reaches a quasi-universal value for simple dielectric fluids of about ≃1.7. Relations to two-dimensional fluids are briefly discussed.

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