Surface normal velocity distribution of sputtered Zr-atoms for light-ion irradiation

1982 ◽  
Vol 194 (1-3) ◽  
pp. 555-559 ◽  
Author(s):  
H.L. Bay ◽  
W. Berres ◽  
E. Hintz
Keyword(s):  
Velocity Distribution ◽  
Ion Irradiation ◽  
Normal Velocity ◽  
Surface Normal

Pure Design Method for Aerofoils in Cascade

1969 ◽  
Vol 11 (5) ◽  
pp. 454-467 ◽  
Author(s):  
K. Murugesan ◽  
J. W. Railly
Keyword(s):  
Exact Solution ◽  
Velocity Distribution ◽  
Design Problem ◽  
Design Method ◽  
Tangential Velocity ◽  
Surface Velocity ◽  
Normal Velocity ◽  
Blade Design ◽  
Blade Shape

An extension of Martensen's method is described which permits an exact solution of the inverse or blade design problem. An equation is derived for the normal velocity distributed about a given contour when a given tangential velocity is imposed about the contour and from this normal velocity an initial arbitrarily chosen blade shape may be successively modified until a blade is found having a desired surface velocity distribution. Five examples of the method are given.

Turbulent structure in free-surface jet flows

1995 ◽  
Vol 291 ◽  
pp. 223-261 ◽  
Author(s):  
D. T. Walker ◽  
C.-Y. Chen ◽  
W. W. Willmarth
Keyword(s):  
Reynolds Number ◽  
Free Surface ◽  
Froude Number ◽  
Tangential Velocity ◽  
Rate Of Change ◽  
Normal Velocity ◽  
Reynolds Stresses ◽  
Velocity Fluctuations ◽  
Surface Normal ◽  
Surface Disturbances

Results of an experimental study of the interaction of a turbulent jet with a free surface when the jet issues parallel to the free surface are presented. Three different jets, with different exit velocities and jet-exit diameters, all located two jet-exit diameters below the free surface were studied. At this depth the jet flow, in each case, is fully turbulent before significant interaction with the free surface occurs. The effects of the Froude number (Fr) and the Reynolds number (Re) were investigated by varying the jet-exit velocity and jet-exit diameter. Froude-number effects were identified by increasing the Froude number from Fr = 1 to 8 at Re = 12700. Reynolds-number effects were identified by increasing the Reynolds number from Re = 12700 to 102000 at Fr = 1. Qualitative features of the subsurface flow and free-surface disturbances were examined using flow visualization. Measurements of all six Reynolds stresses and the three mean velocity components were obtained in two planes 16 and 32 jet diameters downstream using a three-component laser velocimeter. For all the jets, the interaction of vorticity tangential to the surface with its ‘image’ above the surface contributes to an outward flow near the free surface. This interaction is also shown to be directly related to the observed decrease in the surface-normal velocity fluctuations and the corresponding increase in the tangential velocity fluctuations near the free surface. At high Froude number, the larger surface disturbances diminish the interaction of the tangential vorticity with its image, resulting in a smaller outward flow and less energy transfer from the surface-normal to tangential velocity fluctuations near the surface. Energy is transferred instead to free-surface disturbances (waves) with the result that the turbulence kinetic energy is 20% lower and the Reynolds stresses are reduced. At high Reynolds number, the rate of evolution of the interaction of the jet with the free surface was reduced as shown by comparison of the rate of change with distance downstream of the local Reynolds and Froude numbers. In addition, the decay of tangential vorticity near the surface is slower than for low Reynolds number so that vortex filaments have time to undergo multiple reconnections to the free surface before they eventually decay.

A P.I.V. Processing Technique for Directly Measuring Surface-Normal Velocity Gradient at a Free Surface

2005 ◽  
Author(s):  
Tuy N. M. Phan ◽  
Chuong V. Nguyen ◽  
John C. Wells
Keyword(s):  
Free Surface ◽  
Channel Flow ◽  
Velocity Gradient ◽  
Open Channel ◽  
Open Channel Flow ◽  
Processing Technique ◽  
High Mass ◽  
Normal Velocity ◽  
Uniform Compression ◽  
Surface Normal

Compressive surface-normal velocity gradient at a free surface leads to high mass transfer across a free surface. Our research aims to directly measure this velocity gradient at the free surface by proposing an advanced Particle Image Velocimetry (PIV) technique and simultaneously evaluate its applicability. This technique, PIV/IG (Interface Gradiometry), was proposed by Nguyen et al. (2004) to directly measure wall velocity gradient with high S.N.R. Herein, we adapt this technique to measure the compressive surface-normal velocity gradient at the free surface of open channel flow with minimal fluctuation of water surface. We validate this technique in a two-component PIV configuration by synthetic PIV images corresponding to uniform compression, linearly-varying compression, and a velocity field based on DNS data of open channel flow at friction Reynolds number Reτ = 240 and zero Froude number. The results clearly show that this technique works much better than the velocity differentiation method. The effect of template size on the measured value is evaluated.

Prediction of Surface Normal Velocity for an Arbitrary Acoustic Source Using an Equivalent Phased Array Method

1999 ◽  
Vol 38 (Part 1, No. 7A) ◽  
pp. 4233-4235
Author(s):  
Tomoki Yokoyama ◽  
Tetsuro Teshima ◽  
Akio Hasegawa
Keyword(s):  
Phased Array ◽  
Normal Velocity ◽  
Acoustic Source ◽  
Surface Normal

Modification of Near-Wall Turbulent Structure in Channel Flow by Dosing a Small Amount of Polymer Solution

2017 ◽  
Author(s):  
Yushi Okamura ◽  
Tomohiro Kurose ◽  
Yasuo Kawaguchi
Keyword(s):  
Velocity Distribution ◽  
Polymer Solution ◽  
Polymer Concentration ◽  
Water Soluble ◽  
Polymer Additives ◽  
Normal Velocity ◽  
Water Soluble Polymer ◽  
Low Speed ◽  
Wide Range ◽  
Near Wall

The phenomenon known as Toms effect can impart viscoelasticity to a water flow when a small amount of water-soluble polymer is added. The resulting viscoelastic fluid generates viscoelastic stress in the flow, dramatically reducing the turbulent stress. In this study, the spatial distribution of velocity is measured using a stereo-PIV method in the streamwise-spanwise plane parallel to the wall. Modification of the near wall turbulence by the polymer solution blown slowly from a permeable wall was investigated by analyzing the velocity distribution acquired by stereo-PIV measurements. Experimental results reveal that streamwise local mean velocity decreases as the dosed polymer concentration increases. The skewness factor at this height shifts from 0 to positive by adding the polymer, which indicates intensified turbulent coherent structure. Moreover, the spatial two-point correlation function calculated from streamwise velocity fluctuations maintains its high correlation with the streamwise direction. It is consistent with the finding from the instantaneous velocity distribution, which shows that the flection of low-speed streaks is suppressed. Next, it is revealed that the normal velocity at the wall for low-speed fluid is decreased dramatically by polymer additives. Moreover, applying the quadrant analysis, it is confirmed that ejection events are suppressed with decreasing normal velocity at the wall. Suppression of ejection motion affects to the turbulence in the log law layer. We conclude that this is one reason that turbulence is suppressed in a wide range of the shear layer by polymer additives present only in the vicinity of the wall.

A Pressure Index for Predicting the Effect of Flow Profiles on Orifice Meter Performance

1966 ◽  
Vol 88 (1) ◽  
pp. 93-100 ◽  
Author(s):  
H. S. Ghazi
Keyword(s):  
Velocity Distribution ◽  
Discharge Coefficient ◽  
Prediction Method ◽  
Wall Pressure ◽  
Normal Velocity ◽  
Pressure Measurements ◽  
Pressure Index ◽  
Flow Profiles

The influence of upstream non-normal velocity distributions on orifice meters is studied experimentally. Several parameters, based on the velocity distribution, were found to correlate with the discharge coefficient. A pressure index, based on wall-pressure measurements, was also shown to correlate with the discharge coefficient. An examination of a proposed prediction method using the pressure index, showed that it appears possible to predict the performance of orifice meters when the approach profiles are non-normal.

Sign in / Sign up

Export Citation Format

Share Document