scholarly journals Experimental measurements of macro-particle dispersion in grid turbulence and application to a stochastic numerical model for solid body turbulent diffusion

2011 ◽  
Author(s):  
A. Joly ◽  
F. Moulin ◽  
S. Cazin ◽  
A. Astruc ◽  
D. Violeau
Keyword(s):  
Numerical Model ◽  
Solid Body ◽  
Turbulent Diffusion ◽  
Particle Dispersion ◽  
Experimental Measurements ◽  
Grid Turbulence

Multifidelity Recursive Cokriging for Dynamic Systems' Response Modification

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Luigi Bregant ◽  
Lucia Parussini ◽  
Valentino Pediroda
Keyword(s):  
Numerical Model ◽  
Numerical Simulations ◽  
Dynamic Systems ◽  
System Optimization ◽  
The Other ◽  
Experimental Measurements ◽  
Reciprocal Influence ◽  
Tests And Measurements ◽  
Invaluable Tool ◽  
Mixed Approach

In order to perform the accurate tuning of a machine and improve its performance to the requested tasks, the knowledge of the reciprocal influence among the system's parameters is of paramount importance to achieve the sought result with minimum effort and time. Numerical simulations are an invaluable tool to carry out the system optimization, but modeling limitations restrict the capabilities of this approach. On the other side, real tests and measurements are lengthy, expensive, and not always feasible. This is the reason why a mixed approach is presented in this work. The combination, through recursive cokriging, of low-fidelity, yet extensive, numerical model results, together with a limited number of highly accurate experimental measurements, allows to understand the dynamics of the machine in an extended and accurate way. The results of a controllable experiment are presented and the advantages and drawbacks of the proposed approach are also discussed.

scholarly journals Rotation of the Primary Component of Algol

1980 ◽  
Vol 88 ◽  
pp. 223-224
Author(s):  
S. M. Rucinski
Keyword(s):  
Numerical Model ◽  
Angular Velocity ◽  
Least Squares ◽  
Solid Body ◽  
Primary Component ◽  
Rotation Parameter ◽  
Velocity Versus ◽  
Least Squares Solution

1.8 A° segment of the Algol A spectrum centered at 1075.55 A° line of Ni II was scanned repeatedely with the 0.05 A° resolution from the Copernicus satellite. The numerical model is described in which 37 out of the total 55 scans obtained during two eclipses were combined in a least-squares solution, to determine the period of rotation and degree of non-solid rotation of Algol A. The period of rotation suggests full synchronism of rotational and orbital motions; the equatorial velocity is Ve = 53 ± 3 km/s. The non-solid rotation parameter ‘s’ measuring the distribution of angular velocity versus stellar latitude in ω = ωe (1 - s + s cos2 ϑ) has been found equal s = 0.07 ± 0.25 indicating the rotation law not far from solid body.

Thermal Cycling Simulation during Remelting Process of the Steel ASTM A743-CA6NM

2014 ◽  
Vol 1082 ◽  
pp. 100-105
Author(s):  
Camila Almeida Martins ◽  
Jhon Jairo Ramirez-Behainne
Keyword(s):  
Numerical Model ◽  
Thermal Cycling ◽  
Material Properties ◽  
Three Dimensional ◽  
Fusion Line ◽  
Maximum Deviation ◽  
Experimental Measurements ◽  
Ansys Fluent ◽  
Simplifying Assumptions ◽  
Volume Method

This study aimed to model numerically the thermal cycling resulting from the steel ASTM A743-CA6NM remelting process. The problem was solved with the support of the commercial software ANSYS / FLUENT ® 14.5 for the three-dimensional case using the finite volume method. The following simplifying assumptions were adopted: heat loss by natural convection, absence of radiation, no phase change, concentrated heat source, and thermophysical properties independent of temperature. The results were analyzed for two different current intensities: 90A and 130A, and compared with experimental measurements. The peak temperatures of the thermocouples near the fusion line for the current of 130A were well represented by the numerical model, with a maximum deviation of 9.62%. In the case of the more remote thermocouples from the fusion line, the best results were obtained for the current of 90A, not exceeding 5% of deviation. In general, it was found that the tested body is heated faster than in simulations. This can be considered as a consequence of the simplification in material properties, which were assumed constants with temperature. The results of this study demonstrate that, given the adopted simplifications, the numerical model was able to satisfactorily reproduce the experimentally measured thermal cycles.

Solidification Heat Transfer and Base Separation Analysis in the Casting of an Energetic Material in a Projectile

2005 ◽  
Author(s):  
Dawei Sun ◽  
S. Ravi Annapragada ◽  
Suresh V. Garimella ◽  
Sanjeev Sing
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Numerical Model ◽  
Residual Stresses ◽  
Energetic Materials ◽  
Energetic Material ◽  
Complex Geometries ◽  
Experimental Measurements ◽  
Linear Temperature ◽  
High Prandtl Number

This paper investigates the problem of base separation in the casting of energetic materials in a projectile. Special challenges that arise in casting high Prandtl number energetic materials in projectiles of complex geometries are addressed. A comprehensive numerical model is developed by integrating finite volume and finite element methods to analyze the thermal and flow fields as well as the residual stresses. The predictions, which are confirmed by experimental measurements, suggest that sustenance of a linear temperature profile along the projectile axis can eliminate base separation, and also reduce residual stresses in the final casting.

scholarly journals ANALYTICAL AND CFD INVESTIGATION OF TURBULENT DIFFUSION MODEL FOR PARTICLE DISPERSION AND DEPOSITION

1970 ◽  
Vol 40 (1) ◽  
pp. 39-53
Author(s):  
Alamgir Hossain ◽  
Jamal Naser
Keyword(s):  
Diffusion Model ◽  
Turbulent Diffusion ◽  
Particle Deposition ◽  
Fluid Velocity ◽  
Particle Diameter ◽  
Particle Dispersion ◽  
Homogeneous Distribution ◽  
Lower Velocity ◽  
Different Depths ◽  
Diffusion Particle

A 2D analytical turbulent diffusion model for particle dispersion and deposition at different heights across the pipe flow and circumferential deposition has been developed. This liquid-solid turbulent diffusion model presented in this paper has emanated from an existing gas-liquid turbulent diffusion model. Simultaneously a comprehensive 3D numerical investigation has been carried out to study the above making of multiphase mixture model available in Fluent 6.1. In both studies different particles sizes and densities were used. The deposition was studied as a function of particle diameter, density and fluid velocity. The deposition of particles, along the periphery of the wall and at different depths, was also investigated. Both studies showed that the deposition of heavier particles at the bottom of the pipe wall was found to be higher at lower velocities and lower at higher velocities. The lighter particles were found mostly suspended with homogeneous distribution. Smaller particles were also suspended with marginal higher concentration near the bottom of the wall. This marginal higher concentration of the smaller particles was found to be slightly pronounced for lower velocity. The larger particles clearly showed deposition near the bottom of the wall. These analogies of particles are well discussed with the ratio between free flight velocity and the gravitational settling velocity. Key Words: Multiphase flow, turbulence diffusion, particle deposition, horizontal flow.   doi: 10.3329/jme.v40i1.3472 Journal of Mechanical Engineering, Vol. ME40, No. 1, June 2009 39-53

A Turbulent Model for Gas-Particle Jets

2000 ◽  
Vol 122 (3) ◽  
pp. 505-509 ◽  
Author(s):  
J. Garcı´a ◽  
A. Crespo
Keyword(s):  
Mixing Layer ◽  
Stokes Number ◽  
Particle Dispersion ◽  
Lagrangian Model ◽  
Grid Turbulence ◽  
Mean Velocity ◽  
Dissipation Term ◽  
Particle Flows ◽  
Integral Scales ◽  
Kolmogorov Constant

This work is concerned with turbulent diffusion in gas-particle flows. The cases studied correspond to dilute flows and small Stokes number, this implies that the mean velocity of the particles is very similar to that of the fluid element. The classical k-ε method is used to model the gas-phase, modified with additional terms for the k and ε equations, that takes into account the effect of particles on the carrier phase. The additional dissipation term included in the equation for k is due to the slip between phases at an intermediate scale, far from both the Kolmogorov and the integral scales. This term has a proportionality constant equal to 3/2 of Kolmogorov constant, C0. In this paper, a value of 3.0 has been used for this constant as suggested by Du et al., 1995, “Estimation of the Kolmogorov Constant C0 for the Langarian Structure Using a Second-Order Lagrangian Model of Grid Turbulence,” Phys. Fluids 7, (12), pp. 3083–3090. The additional source term for the ε equation is taken as proportional to ε/k, as is usually done. In all experiments analyzed the particles increased the dissipation of turbulent kinetic energy. A comparison is made between the results obtained with the model proposed in this work and the experiments of Shuen et al., 1985, “Structure of Particle-Laden Jets: Measurements and Predictions,” AIAA Journal, 23, No. 3, and Hishida et al., 1992, “Experiments on Particle Dispersion in a Turbulent Mixing Layer,” ASME Journal of Fluids Engineering, 119, pp. 181–194. [S0098-2202(00)02103-9]

scholarly journals Analysis of the State of Stress in Cathode Block of an Aluminium Electrolytic Cell During Formation of Connection with the Steel Pin by Cast Iron Pouring

2016 ◽  
Vol 61 (4) ◽  
pp. 1869-1874
Author(s):  
J. Piekło ◽  
M. Maj
Keyword(s):  
Cast Iron ◽  
Numerical Model ◽  
Electrolytic Cell ◽  
The State ◽  
Effect Of Temperature ◽  
Experimental Measurements ◽  
Carbon Block ◽  
Cathode Block ◽  
State Of Stress

Abstract The article presents various aspects of the analysis of the state of stress in carbon block induced by the effect of temperature when a steel pin is connected to the block by pouring a shaped groove with cast iron. Changes in the temperature and state of stress in the block were examined by FEM (Abaqus program). The numerical model was validated by experimental measurements of pin deflection during pouring of the groove with cast iron.

Experimental Measurements of Temperature Distribution in Three Dimensional Stacked Package

2007 ◽  
Author(s):  
Anand Desai ◽  
James Geer ◽  
Bahgat Sammakia
Keyword(s):  
Experimental Study ◽  
Heat Conduction ◽  
Steady State ◽  
Temperature Distribution ◽  
Numerical Model ◽  
Analytical Solution ◽  
Three Dimensional ◽  
Power Input ◽  
Experimental Measurements ◽  
Steady State Heat

This paper presents the results of an experimental study of steady state heat conduction in a three dimensional stack package. The temperatures are measured at different interfaces within the stacked package. Delphi devices are used in the experiment which enables controlled power input and surface temperature of the devices. The experiment is carried out for three different boundary conditions on the package. The power input in varied to study its effects. A numerical model is created to compare to the experimental results. The results are also compared with the analytical solution presented in Desai et al [5] and Geer et al [6]. The results indicate that the experimental, numerical and analytical solutions follow the same trend. The agreement between the experimental and numerical results improves when the lateral losses are taken into account.

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