Velocity distribution measurement

One characteristic of shear banded flow is the presence of fluctuations in the flow field. Such fluctuations also occur in some glassy colloidal materials at colloid volume fractions close to the glass transition. One such system is the soft gel formed by crowded monodisperse multiarm (122) star 1,4-polybutadienes in decane. Using NMR velocimetry Holmes et al. [23] found evidence for fluctuations in the flow behavior across the gap of a wide gap concentric cylindrical Couette device, in association with a degree of apparent slip at the inner wall. The timescale of these fluctuations appeared to be rapid (with respect to the measurement time per shear rate in the flow curve), in the order of tens to hundreds of milliseconds. As a result, the velocity distributions, measured at different points across the cell, exhibited bimodal behavior, as apparent in Figure 2.8.13. These workers interpreted their data... 

Velocity-distribution Measurements for Product Ions of Collision-induced Dissociations 3Sb... 

Figure 1.9 Typical velocity distributions measured in the horizontal-plane problem by Ben-novitsky [56] (a) relative obstructed cross section a>veg/a>0 = 0.19, and (b) a>veg/a>0 = 0.45. Line markings 1 - border of the vegetated area 2 - velocity distribution if vegetation is absent 3 -flume symmetry line.

Mean Velocity Characteristics for Constant Fluid Properties. Mean velocity distributions measured in turbulent boundary layers when the fluid properties are uniform (low speeds and small temperature differences between the free stream and surface) are described in the reviews of Refs. 78 and 79. At a given station, the turbulent boundary layer is composed of two regions with velocity profiles described by the law of the wall and the law of the wake after Coles [80, 81]. 

Velocity distribution measurements in the polystyrene slurries showed that k in the slurry is somewhat higher than the clear fluid value of 0.4. Using estimated y values, the Bagnold numbers were <450 in all cases and <40 for the fine particles. It appears Bagnold s criterion does not apply to these turbulent flows. 

The parameter sets P(x,y) and R(x,y) can be determined from the local tracer concentration and velocity distributions measured in each cross section of the column. 

Fig. 1 Nondimensional velocity distribution measured in a turbulent channel flow at two different Reynolds numbers...

Hydraulic tests to assess the flow distribution and measure vibration of tube bundle are carried out on a 60 degree sector model of SG (fig 13a). The velocity distribution measured in the inlet plenum was found matching with prediction of the 3D hydraulic calculations (fig 13b). Vibration measurements are carried out in the straight spans and expansion bend regions. Although the vibration level is found higher in the inlet span where cross flow takes place across the tube bundle, it is within the acceptable values based on structural mechanics analysis (fig 13c). 

The air velocity distribution, measured at 49 points over the cross section of the chamber at a height corresponding to the middle of the rack that holds the specimens, exhibited an average speed of 38.2 m/min with a standard deviation of 10.6 m/min. The concentration of (NH4)2S04 particles generated from a 0.01 M solution of the salt was found to be quite uniform over the cross section of the chamber (see Fig. 3). Variation of the deposition rate to surfaces being tested is accomplished by regulating the airflow velocity. 

The vortex development of a low-density polyethylene in different flat dies under various proeessing conditions has been analyzed by the Finite Element Method enploying the modified White-Metzner model as constitutive equation. The theoretical results are conpared with the velocity distributions measured by Laser-Doppler Velocimetry (LDV). 

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