Experimental and Numerical Study of Pentacene Molecular Beam Seeded in the Free Jet of Helium

2011 ◽  
Author(s):  
A. K. Rebrov ◽  
P. A. Skovorodko ◽  
T. Toccoli ◽  
M. Tonezzer ◽  
N. Coppedè ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Numerical Study ◽  
Free Jet

Numerical Study of the Mean and Filtered Characteristics of Turbulent Jets Impinging on Convex and Flat Surfaces Using LES

2012 ◽  
Author(s):  
Adra Benhacine ◽  
Zoubir Nemouchi ◽  
Lyes Khezzar ◽  
Nabil Kharoua
Keyword(s):  
Convex Surface ◽  
Numerical Study ◽  
Three Dimensional ◽  
Turbulent Jets ◽  
Scale Model ◽  
Wall Jet ◽  
Potential Core ◽  
Flat Surfaces ◽  
Free Jet ◽  
Eddy Simulation

A numerical study of a turbulent plane jet impinging on a convex surface and on a flat surface is presented, using the large eddy simulation approach and the Smagorinski-Lilly sub-grid-scale model. The effects of the wall curvature on the unsteady filtered, and the steady mean, parameters characterizing the dynamics of the wall jet are addressed in particular. In the free jet upstream of the impingement region, significant and fairly ordered velocity fluctuations, that are not turbulent in nature, are observed inside the potential core. Kelvin-Helmholtz instabilities in the shear layer between the jet and the surrounding air are detected in the form of wavy sheets of vorticity. Rolled up vortices are detached from these sheets in a more or less periodic manner, evolving into distorted three dimensional structures. Along the wall jet the Coanda effect causes a marked suction along the convex surface compared with the flat one. As a result, relatively important tangential velocities and a stretching of sporadic streamwise vortices are observed, leading to friction coefficient values on the curved wall higher than those on the flat wall.

Anisotropic Etching of Heavily Doped Polysilicon by a Hot Cl2 Molecular Beam

1990 ◽  
Vol 201 ◽  
Author(s):  
T. Ono ◽  
S. Hiraoka ◽  
K. Suzuki
Keyword(s):  
Etch Rate ◽  
Molecular Beam ◽  
Anisotropic Etching ◽  
Free Jet ◽  
Etching Condition ◽  
Heavily Doped ◽  
Nitrogen Radical

AbstractAnisotropic etching of n+ poly-Si is achieved using a hot Cl2 molecular beam and a sidewall protection technique. A hot molecular beam is produced by a free jet expansion of a gas heated in a furnace. A nitrogen radical beam is used to prevent the sidewall etching. The etch rate of n+ poly-Si is 4.3 nm/min at the anisotropic etching condition.

Translational freezing in free jet expansions, with special reference to molecular beam formation

1969 ◽  
Vol 47 (12) ◽  
pp. 2161-2165 ◽  
Author(s):  
Rodney L. LeRoy ◽  
Jacques M. Deckers
Keyword(s):  
Distribution Function ◽  
Transition Region ◽  
Molecular Beam ◽  
Collision Frequency ◽  
Collision Cross Section ◽  
Experimental Studies ◽  
Velocity Distribution Function ◽  
Free Jet ◽  
Beam Formation ◽  
Good Agreement

A theoretical model is described which can be used to calculate the velocity distribution function in the transition region of a free jet expansion. It makes use of a simple mechanism to account for the way in which collisions "perturb" the distribution function which would apply in the absence of collisions. The results are compared with experimental studies of argon beams isolated from free jet sources. If the collision frequency is calculated using a hard sphere collision cross section of (25 ± 5) Å2, good agreement with experimental beam intensity profiles is obtained. In the transition region computed values of the bulk mass velocity, and of the parallel and perpendicular temperatures, are intermediate between the values which would be found if the flow were collision-dominated or free molecular. In particular the perpendicular temperature varies slowly from a dependence on the −4/3 power of the distance from the source, approaching monotonically a −2 power dependence at large distances.

A numerical study of the nozzle/diffuser micropump

2008 ◽  
Vol 222 (3) ◽  
pp. 525-533 ◽  
Author(s):  
K-S Yang ◽  
I-Y Chen ◽  
K-H Chien ◽  
C-C Wang
Keyword(s):  
Numerical Study ◽  
Geometric Dimension ◽  
Jet Flow ◽  
Opening Angle ◽  
Cross Sectional ◽  
Free Jet ◽  
Chamber Length ◽  
Two Factors ◽  
Versus Amplitude ◽  
Free Jet Flow

This study numerically investigates the performance of micronozzle/diffuser pump subject to the influence of frequency, opening angle, geometric dimension, and amplitude. For the effect of geometric dimension, the effect of chamber length is far more important than that of chamber depth because it can provide much more effective pumping volume. It is found that the net flowrate of a micropump increased with pumping frequency and opening angle. However, a level-off phenomenon of the net flowrate versus amplitude is seen at amplitudes nearby 150–200 μm and at an opening angle above 10°. This phenomenon is associated with two factors that compensate with each other. One is the free jet flow from the outlet that overturns and blocks the flow from the inlet. The other is the reduction of the strength of jet flow at a larger amplitude owing to effective increase of cross-sectional area.

Numerical study of turbulent round free jet

2018 ◽  
Author(s):  
Niloy Das ◽  
S. M. Rakibul Islam ◽  
Sayeed Mohammed ◽  
Mohammad Nasim Hasan
Keyword(s):  
Numerical Study ◽  
Free Jet

Numerical study of MHD effect on liquid metal free jet under complex magnetic fields

2006 ◽  
Vol 81 (8-14) ◽  
pp. 1451-1458 ◽  
Author(s):  
Xiao-Yong Luo ◽  
Alice Ying ◽  
Mohamed Abdou
Keyword(s):  
Magnetic Fields ◽  
Liquid Metal ◽  
Numerical Study ◽  
Metal Free ◽  
Free Jet

Effects of the Shape of a Nozzle With Chevrons on the Dynamics of Turbulent Impinging Jet

2016 ◽  
Author(s):  
Sadek Horra ◽  
Zoubir Nemouchi ◽  
Lyes Khezzar
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Impinging Jet ◽  
Point Of View ◽  
Geometrical Parameters ◽  
Free Jet ◽  
Fundamental Point ◽  
Nozzle Shape ◽  
Heat And Fluid Flow ◽  
Plate Distance

This work is a numerical study of a turbulent impinging jet issuing from a nozzle with chevrons. The Reynolds number based on the jet exit velocity and nozzle diameter is equal to 5000 corresponding to a low Mach number of 0.0057 at the nozzle exit. The main objectives of the investigation, inspired by the work of Violato et al. (Int. J. of Heat and Fluid Flow, 37, 2012), are to highlight, from a fundamental point of view, the effects of the nozzle shape and the nozzle-to-plate distance on the mean parameters characterizing the dynamics of the flow in question. The nozzle configurations considered are a circular nozzle without chevrons and nozzles provided with 4 and 6 chevrons. The nozzle-to-plate distance ranges from 2 to 6 nozzle diameters. All the other flow conditions and geometrical parameters used in the different cases treated are identical. Interesting features of the flow are revealed by the obtained results of averaged three-dimensional fields of velocity and turbulent kinetic energy, particularly close to the wall. An attempt is made to bring additional insight into the phenomena in the free jet, the impingement region and the wall jet when using 4, 6 and no chevrons, for different nozzle-to-plate distances.

Numerical study of a free jet multinozzle source

1994 ◽  
Vol 223 (3) ◽  
pp. 255-262 ◽  
Author(s):  
Eugene V. Kuleznev ◽  
Vladimir I. Baranov ◽  
Dmitry N. Trubnikov
Keyword(s):  
Numerical Study ◽  
Free Jet
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