Rapid Granular Flow Down Inclines

1994 ◽  
Vol 47 (6S) ◽  
pp. S240-S244 ◽  
Author(s):  
James T. Jenkins
Keyword(s):  
New York ◽  
Free Surface ◽  
Granular Flow ◽  
Academic Press ◽  
Mean Velocity ◽  
Fluctuation Velocity ◽  
Dense Flows ◽  
The Mean ◽  
Collisional Regime

As an example of the activity in the field of rapid granular flow, we sketch an analysis of a rapid granular flow of identical frictionless spheres that is driven by gravity down an incline. The flow is assumed to be dense, collisional, steady, and fully developed. Because we employ conditions at the base of the flow that are appropriate for a bumpy, frictionless boundary, the analysis is slightly more complicated than that of Savage (1983a, in Theory of Dispersed Multiphase Flow, RE Meyer (ed), Academic Press, New York, 339-358). Because we restrict our attention to dense flows, it is somewhat simpler than that of Richman and Marciniec (1990, J Appl Mech57, 1036-1043). It is essentially that of the dense collisional regime considered by Anderson and Jackson (1992, J Fluid Mech241, 145-168). We outline the determination of the profiles of the mean velocity, fluctuation velocity, and concentration through the depth of the flow and indicate how the boundary conditions provide relations between the depth of the flow, the angle of inclination, the fluctuation velocity at the base of the flow, and the mean velocity at the free surface.

The flow of liquid in a stream from the standard turbine impeller

1979 ◽  
Vol 44 (3) ◽  
pp. 700-710 ◽  
Author(s):  
Ivan Fořt ◽  
Hans-Otto Möckel ◽  
Jan Drbohlav ◽  
Miroslav Hrach
Keyword(s):  
Reynolds Number ◽  
Kinematic Viscosity ◽  
Momentum Flux ◽  
Relative Size ◽  
Mean Velocity ◽  
Axial Profile ◽  
The Mean ◽  
Hot Film ◽  
Turbine Impeller

Profiles of the mean velocity have been analyzed in the stream streaking from the region of rotating standard six-blade disc turbine impeller. The profiles were obtained experimentally using a hot film thermoanemometer probe. The results of the analysis is the determination of the effect of relative size of the impeller and vessel and the kinematic viscosity of the charge on three parameters of the axial profile of the mean velocity in the examined stream. No significant change of the parameter of width of the examined stream and the momentum flux in the stream has been found in the range of parameters d/D ##m <0.25; 0.50> and the Reynolds number for mixing ReM ##m <2.90 . 101; 1 . 105>. However, a significant influence has been found of ReM (at negligible effect of d/D) on the size of the hypothetical source of motion - the radius of the tangential cylindrical jet - a. The proposed phenomenological model of the turbulent stream in region of turbine impeller has been found adequate for values of ReM exceeding 1.0 . 103.

Prediction of the Maximum Number of Repetitions and Repetitions in Reserve From Barbell Velocity

2018 ◽  
Vol 13 (3) ◽  
pp. 353-359 ◽  
Author(s):  
Amador García-Ramos ◽  
Alejandro Torrejón ◽  
Belén Feriche ◽  
Antonio J. Morales-Artacho ◽  
Alejandro Pérez-Castilla ◽  
...  
Keyword(s):  
Body Mass ◽  
General Equation ◽  
Bench Press ◽  
Body Height ◽  
Strong Relationship ◽  
Training Set ◽  
Mean Velocity ◽  
The Mean ◽  
Acceptable Reliability

Purpose: To provide 2 general equations to estimate the maximum possible number of repetitions (XRM) from the mean velocity (MV) of the barbell and the MV associated with a given number of repetitions in reserve, as well as to determine the between-sessions reliability of the MV associated with each XRM. Methods: After determination of the bench-press 1-repetition maximum (1RM; 1.15 ± 0.21 kg/kg body mass), 21 men (age 23.0 ± 2.7 y, body mass 72.7 ± 8.3 kg, body height 1.77 ± 0.07 m) completed 4 sets of as many repetitions as possible against relative loads of 60%1RM, 70%1RM, 80%1RM, and 90%1RM over 2 separate sessions. The different loads were tested in a randomized order with 10 min of rest between them. All repetitions were performed at the maximum intended velocity. Results: Both the general equation to predict the XRM from the fastest MV of the set (CV = 15.8–18.5%) and the general equation to predict MV associated with a given number of repetitions in reserve (CV = 14.6–28.8%) failed to provide data with acceptable between-subjects variability. However, a strong relationship (median r2 = .984) and acceptable reliability (CV < 10% and ICC > .85) were observed between the fastest MV of the set and the XRM when considering individual data. Conclusions: These results indicate that generalized group equations are not acceptable methods for estimating the XRM–MV relationship or the number of repetitions in reserve. When attempting to estimate the XRM–MV relationship, one must use individualized relationships to objectively estimate the exact number of repetitions that can be performed in a training set.

The Shear Layer above and in Urban Canopies

2007 ◽  
Vol 46 (3) ◽  
pp. 368-376 ◽  
Author(s):  
Pablo Huq ◽  
Louis A. White ◽  
Alejandro Carrillo ◽  
Jose Redondo ◽  
Seshu Dharmavaram ◽  
...  
Keyword(s):  
New York ◽  
New York City ◽  
Los Angeles ◽  
Shear Layer ◽  
Urban Canopy ◽  
Ground Level ◽  
Shear Layers ◽  
Mean Velocity ◽  
Building Height ◽  
The Mean

Abstract The nature and role of the shear layer, which occurs at the level of the average building height in urban canopies, are poorly understood. Velocity data are analyzed to determine the characteristics of the shear layer of the urban canopy, defined as the broad, linear segment of the mean velocity profile in a region of high shear. Particle image velocimetry measurements in a water tunnel were undertaken to resolve velocity profiles for urban canopies of two geometries typical of Los Angeles, California, and New York City, New York, for which the aspect ratios (average building height-to-width ratio) H/wb are 1 and 3, respectively. The shear layers evolve with distance differently: For H/wb = 1 the urban canopy shear layer extends quickly from above the building height to ground level, whereas for H/wb = 3 the urban canopy shear layer remains elevated at the vicinity of the building height, only reaching to a depth of z/H ∼ 0.5 far downstream. Profiles of the mean velocity gradient also differ from each other for urban canopies associated with H/wb of 1 or 3. Values of shear dU/dz increase toward ground level for an urban canopy associated with H/wb = 1. For an urban canopy associated with H/wb = 3, localized peaks of shear dU/dz exist at the building height and at ground level, with values of shear decreasing to zero at building midheight and far above the building height. A consequence of the different forms of the shear layers of the two urban canopies is that the ground-level dispersion coefficient is likely to be greater for urban canopies associated with H/wb = 1 than for those associated with H/wb = 3 because of an increased ventilation and exchange mechanism for cities such as Los Angeles relative to cities such as New York City that possess urban canyons.

Isolation and patial sequence of bovine cDNA clones for the high-moility-group protein (HMG-1)

1984 ◽  
Vol 4 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Brian Pentecost ◽  
Gordon H. Dixon
Keyword(s):  
New York ◽  
Dna Sequences ◽  
Complete Sequence ◽  
Cdna Clones ◽  
Academic Press ◽  
Coding Region ◽  
Chromosomal Proteins ◽  
C Terminus ◽  
Group Protein

Several cloned ds cDNAs containing bovine HMG-1 sequences have been isolated from a ds cDNA library prepared from the poly(A)+ mRNA fraction of bovine testis using a pool of synthetic 17-rneric oligo-deoxyribonucleotides with the sequence α2 selected to be complementary to a region of the coding sequence corresponding to the relatively unambiguous amino acid sequence, Glu-Met-Trp-Asn-Asn-Thr. Determination of the DNA sequences in these clones indicates that they represent the 3′ half of the HMG-1 message and contain an unusually long putative 3′ untranslated region of 480 nucleotides. The sequence of the coding region corresponding to the 99 amino acids at the C-terminus of HMG-I has been determined and largely confirms the published primary sequence in this region (Walker 3M, (1982) in: The HMG Chromosomal Proteins, Academic Press, London & New York, pp. 69–88). In addition the cDNA sequence provides a complete sequence of the 30 residue polyacidic region and shows that the nucleotide sequence in this region is a repeating one and that the polyacidic domain comprises the C-terminus of the protein.

Forward and Backward Running Waves in the Arteries: Analysis Using the Method of Characteristics

1990 ◽  
Vol 112 (3) ◽  
pp. 322-326 ◽  
Author(s):  
K. H. Parker ◽  
C. J. H. Jones
Keyword(s):  
Transient Flow ◽  
Impedance Analysis ◽  
Time Domain Analysis ◽  
Mean Velocity ◽  
One Dimensional ◽  
Acceleration And Deceleration ◽  
The Mean ◽  
The One ◽  
Made In

The one-dimensional equations of flow in the elastic arteries are hyperbolic and admit nonlinear, wavelike solutions for the mean velocity, U, and the pressure, P. Neglecting dissipation, the solutions can be written in terms of wavelets defined as differences of the Riemann invariants across characteristics. This analysis shows that the product, dUdP, is positive definite for forward running wavelets and negative definite for backward running wavelets allowing the determination of the net magnitude and direction of propagating wavelets from pressure and velocity measured at a point in the artery. With the linearizing assumption that intersecting wavelets are additive, the forward and backward running wavelets can be separately calculated. This analysis, applied to measurements made in the ascending aorta of man, shows that forward running wavelets dominate during both the acceleration and deceleration phases of blood flow in the aorta. The forward and backward running waves calculated using the linearized analysis are similar to the results of an impedance analysis of the data. Unlike the impedance analysis, however, this is a time domain analysis which can be applied to nonperiodic or transient flow.

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