A Similarity Hypothesis for the Two-Point Velocity Correlations in a Temporally Evolving Wake

Detonating code is a flexible code with an explosive core. It is used to transmit the ignition of explosives with high detonation velocity in the range of 5.5 to 7 km/s. However, it is difficult to use detonating code for the explosive welding of common metals since the horizontal point velocity usually exceeds the sound velocity. Hence, in the present work, a new method using underwater shock wave generated by the detonation of detonating code was tried. The details of the experimental parameters and the results are presented. From the results it is observed that the above technique is suitable to weld thin metal plates with relatively less explosives.

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Two-point similarity in temporally evolving plane wakes

Journal of Fluid Mechanics ◽

10.1017/s0022112006003260 ◽

2007 ◽

Vol 577 ◽

pp. 287-307 ◽

Cited By ~ 12

Author(s):

D. EWING ◽

W. K. GEORGE ◽

M. M. ROGERS ◽

R. D. MOSER

Keyword(s):

Large Scale ◽

Single Point ◽

Similarity Solutions ◽

Similarity Analysis ◽

Governing Equations ◽

Large Scale Structures ◽

Rate Dependent ◽

Dependent Parameter ◽

Scale Structures ◽

Point Velocity

The governing equations for the two-point correlations of the turbulent fluctuating velocity in the temporally evolving wake were analysed to determine whether they could have equilibrium similarity solutions. It was found that these equations could have such solutions for a finite-Reynolds-number wake, where the two-point velocity correlations could be written as a product of a time-dependent scale and a function dependent only on similarity variables. It is therefore possible to collapse the two-point measures of all the scales of motions in the temporally evolving wake using a single set of similarity variables. As in an earlier single-point analysis, it was found that the governing equations for the equilibrium similarity solutions could not be reduced to a form that was independent of a growth-rate dependent parameter. Thus, there is not a single ‘universal’ solution that describes the state of the large-scale structures, so that the large-scale structures in the far field may depend on how the flow is generated.The predictions of the similarity analysis were compared to the data from two direct numerical simulations of the temporally evolving wakes examined previously. It was found that the two-point velocity spectra of these temporally evolving wakes collapsed reasonably well over the entire range of scales when they were scaled in the manner deduced from the equilibrium similarity analysis. Thus, actual flows do seem to evolve in a manner consistent with the equilibrium similarity solutions.

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Lagrangian similarity hypothesis applied to diffusion in turbulent shear flow

Deep Sea Research and Oceanographic Abstracts ◽

10.1016/0011-7471(64)90032-4 ◽

1964 ◽

Vol 11 (4) ◽

pp. 658

Keyword(s):

Shear Flow ◽

Turbulent Shear ◽

Turbulent Shear Flow ◽

Similarity Hypothesis

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The Similarity Hypothesis and New Analytical Support on the Estimation of Horizontal Infiltration into Sand

Applied and Environmental Soil Science ◽

10.1155/2010/657402 ◽

2010 ◽

Vol 2010 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Celso L. Prevedello ◽

Jocely M. T. Loyola

Keyword(s):

Analytical Solution ◽

Soil Water ◽

Power Law ◽

Specific Power ◽

Water Density ◽

Diverse Range ◽

Similarity Hypothesis ◽

Initial Soil ◽

Water Contents ◽

Soil Water Contents

A method based on a specific power-law relationship between the hydraulic head and the Boltzmann variable, presented using a similarity hypothesis, was recently generalized to a range of powers to satisfy the Bruce and Klute equation exactly. Here, considerations are presented on the proposed similarity assumption, and new analytical support is given to estimate the water density flux into and inside the soil, based on the concept of sorptivity and on Buckingham-Darcy's law. Results show that the new analytical solution satisfies both theories in the calculation of water density fluxes and is in agreement with experimental results of water infiltrating horizontally into sand. However, the utility of this analysis still needs to be verified for a variety of different textured soils having a diverse range of initial soil water contents.

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Estimating discharge in rivers through the combined use of dimensionless isovels and point velocity measurements

Hydrology Research ◽

10.2166/nh.2017.029 ◽

2017 ◽

Vol 48 (3) ◽

pp. 616-633 ◽

Cited By ~ 3

Author(s):

G. Farina ◽

S. Alvisi ◽

M. Franchini

Keyword(s):

Cross Section ◽

Cross Sections ◽

Accurate Estimation ◽

Velocity Measurements ◽

Combined Use ◽

Point Velocity ◽

New Formulation ◽

The Relationship ◽

River Cross Section

This paper presents a procedure for estimating discharge in a river cross-section based on the combined use of dimensionless isovels and point velocity measurements. Specifically, taking the Biot–Savart law on the magnetic field induced by an electric current in a wire as their basis as already done by other researchers, the authors propose a new formulation of the relationship characterizing the effect of the wetted perimeter on the range of velocities in a cross-section in order to take explicit account of roughness, expressed by means of Manning's coefficient. Once appropriately nondimensionalized, the isoeffect contours can be read as dimensionless isovels. Assuming in situ velocity measurements are available, discharge at a cross-section can be computed using two different methods. The proposed procedure was applied to six case studies characterized by river cross-sections which differed greatly from one another. The results show that the two methods proposed for estimating discharge lead to equivalent outcomes, and in all the cases the procedure as a whole enables a sufficiently accurate estimation of discharge, even when it is based on a limited number of velocity measurements or on the measurement of maximum surface-water velocity alone.

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